Consensus report on acoustic rhinometry and rhinomanometry 2000

1 

FOREWORD 

In 1977 EB Kern summarised many years of experience with 

rhinomanometry with more than 20,000 rhinometric examinations 

and concluded: It is fully recognised that standardisation 

of rhinomanometry requires further inquiry and evaluation and 

that this (the presented work, ed.) is not the final communication 

on the subjects but merely a current consensus from a limited 

few in the working field. 

The history of acoustic rhinometry is not long. It began in 1987, 

when Andrew C. Jackson from Boston University, Department 

of Biomedical Engineering, brought knowledge and equipment 

to Århus. The theory of measuring cavitity dimensions by use 

of sound was not new, but nobody had until then systematically 

applied the method to the nasal cavity. Andrew Jackson provided 

hardware and software for the initial measurements, and 

he also suggested that the area distance curves were best portrayed 

with logarithmic area scales. That was the birth of acoustic 

rhinometry. 

The widespread interest in the method soon made it obvious 

that standardisation would be useful, and in 1994 the 

Standardisation Committee on Objective Assessment of the 

Nasal Airway of the European Rhinological Society founded 

the Subcommittee on Standardisation of Acoustic Rhinometry. 

A provisonal <strong>report</strong> was presented to the ERS in Vienna, 1998. 

This work has now been updated and is presented in this supplement 

of Rhinology. 

Together with the standardisation document is published a 

small number of papers related to standardisation and different 

applications of acoustic rhinometry. They have been chosen as 

illustrations of the state of the art, but other papers might have 

served this purpose equally well. The editors fully realise that 

that without valuable support from members of the 

Standardisation Committee and others, this standardisation 

document could not have been made. We fully acknowledge 

their contribution. Furthermore, we acknowledge G.M. 

Instruments, Hood Laboratories, and Rhinometrics for contribution 

to the printing costs of the supplement. 

What E. B. Kern said about rhinomanometry in 1977 is equally 

true for acoustic rhinometry in 2000: it is not the final communication 

on the subject, but merely a current consensus from a 

limited few in the working field. Standardisation of acoustic rhinometry 

is a continuous process, which should be in accordance 

with the technical development, and the anatomical, physiological, 

and clinical understanding of what we measure - but it is 

a start. 

Ole F. Pedersen and Ole Hilberg, editors.

2 

INTRODUCTION 

The nose is the first part of the airways, and normal nasal breathing 

requires a patent nasal airway. In addition, nasal blockage 

is unpleasant and compromises quality-of-life. 

Nasal disorders, causing reduced nasal airway patency are frequent 

and allergic rhinitis occurs with increasing prevalence. In 

daily clinical work, and also in most controlled trials of drug 

intervention, nasal blockage is estimated merely by the patient's 

subjective sensation of nasal congestion, having a considerable 

inter-individual variation. 

In the lower airway equivalent to rhinitis, asthma, objective 

measurement of airway patency is a must in clinical trials and 

used as a routine in clinical work. If rhinitis research should be 

lifted to the same level as asthma research, then objective measurements 

of nasal patency are needed. 

Rhinomanometry has been used for decades, but it has never 

gained widespread usage due to difficulties in patient collaboration. 

Nasal peak flow measurement has also been used in some 

clinical trials, but it is a highly unphysiological method. 

In recent years, acoustic rhinometry has been developed as a 

method with potential usefulness not only in clinical research 

but also in the daily work with rhinitis patients and patients 

requiring nasal surgery. In these papers the pioneers in acoustic 

rhinometry give a state-of-the-art presentation of this new and 

promising method, and this supplement may help, not only to 

improve standardisation of acoustic rhinometry, but also to 

improve clinical and research work in rhinitis. 

Niels Mygind

Supplement 16, 3–17, 2000 

Acoustic rhinometry: recommendations for 

technical specifications and standard operating 

procedures 

O. Hilberg and O.F. Pedersen 

Institute of Environmental and Occupational Medicine, University of Aarhus, DK-8000, Aarhus C, Denmark 

SUMMARY 

This document is the result of the work and discussion of the Standardisation Committee on 

Acoustic Rhinometry and presents guidelines for quality control and optimal application of 

acoustic rhinometry at its present stage. It is suggested that: 

1. A well-defined standard nose is used for testing and optimising the equipment (data for a 

standard nose is given in the paper). 

2. Procedures for evaluation of accuracy and repeatability of the measurements in the standard 

nose are presented, and error limits are defined for the area-distance curve as a whole, 

for the minimum cross- sectional area and for the volume from 0-5 cm into the nose. 

3. Publication of results should include the volume 0-5 cm into the nose (volume from 2-5 cm 

for mucosal changes) the minimum cross-sectional area or preferably the two first minima 

and the distances to those areas. 

4. The operator should be trained, follow a standard operating procedure and the environmental 

conditions (temperature and noise) be controlled. 

5. Attention should be given to the nosepiece and the coupling between the equipment and the 

nose to obtain correct position, and sufficient seal without disturbing the anatomy. 

6. The manufacturer should give information about the performance of the equipment, calibration 

procedures and maintenance, hygiene, environmental and safety standards. 

Key words: guidelines, standardisation, reproducibility 

INTRODUCTION 

Acoustic rhinometry is a technique, which allows measurement 

of the relationship between the cross- sectional area of the nasal 

cavity, and the distance into the nasal cavity. The method is 

based on analysis of sound reflection from the nasal cavity 

taking into account properties of incident sound submitted to 

the nasal cavity, along with associated reflected sound waves 

(Hilberg et al., 1989). Although, validation has shown satisfactory 

results (Mayhew et al., 1993), the technique has some physical 

limitations, which cannot be changed, but some technical 

aspects of the equipment can be adjusted to obtain higher 

accuracy (Hilberg et al., 1993). Furthermore, if the method is 

properly standardised the variability can be reduced and a better 

reproducibility assured. 

The physical principle of the technique is that sound in a tube, 

in this case the airways, is reflected by changes in acoustic 

impedance caused by changes in tube dimensions. Changes in 

cross-sectional area are proportional to changes in acoustic 

impedance provided the propagating wave is one-dimensional. 

If the incident wave is compared to the reflected waves it is possible 

to determine changes in the cross-sectional area. Taking 

into account the time interval between the incident and reflected 

waves and the speed of sound allows the distance to a certain 

change in cross-sectional area to be determined. 

Up till now acoustic rhinometry has been under development, 

and results from different centres have been difficult to compare 

due to differences in equipment and measurement techniques. It 

is therefore necessary to focus on the best ways of using the technique 

and suggest some simple standard operating procedures 

that will enhance the validity and ability to compare results. 

A committee under the European Rhinological Society has discussed 

the technique and practical use of acoustic rhinometry 

and suggests the guidelines described below. These guidelines 

should be considered preliminary and there may be changes in 

accordance with new knowledge and technical development. 

DEFINITIONS 

For a more precise discussion the following definitions (Official 

vocabulary from “International Vocabulary of Basic and General 

Terms in Metrology”, PD 6461 part 1, joint workgroup affiliated 

to ISO, BIPM, IEC, OIML and BSI definitions) should be 

born in mind:

4 Hilberg et al. 

Figure 1. The left panel shows the curve for the standard nose (true areas), and the mean measured curve (10 measurements) +/- 2 SD. The right panel 

shows the repeatability of the measurements described by the coefficient of variation. 

Accuracy - the closeness of agreement between the result of a 

measurement and the (conventional) true value of the measurand. 

In this case the difference between the measured and the 

true areas. 

Repeatability of measurements - the closeness of agreement 

between the results of successive measurements of the same 

measurand carried out subject to all the following constant conditions: 

the same method of measurement, the same observer, 

the same measuring instrument, the same location, the same 

condition of use, and repetition over a short period of time. 

N.B. Highly repeatable measurements need not to be accurate! 

Reproducibility of measurements - the closeness of agreement of 

the results of measurements of the same (constant) measurand 

where the individual measurements are carried out with changing 

conditions such as: method of measurement, observer, 

measuring instrument, location, condition of use, and time. 

Spatial resolution - the ability to discriminate between areas 

along the distance axis. Resolution has a major influence on 

overall accuracy. 

The ability of the acoustic rhinometer to measure changes in 

areas is determined by the sampling frequency, microphone 

characteristics, filtering frequencies and other factors. The 

‘acoustic‘ spatial resolution is determined by the sampling frequency 

of the equipment. 

Coefficient of variation - the standard deviation divided by the 

mean, can be used as a measure of repeatability and reproducibility. 

Optimisation of accuracy and resolution depends on technical 

properties of the equipment and the dimensions of the airway, 

but also partly on the software-algorithms applied in the 

calculations. Variability is an unspecific term which may include 

reproducibility and variation between subjects. 

STANDARDISATION 

Standardisation can be applied to the equipment, the procedures 

used while measuring and presenting data. An instrument, 

which meets the requirements of the standardisation committee, 

should be able to measure a given model with repeatability 

and accuracy better than a given limit. 

Some possibilities to improve the results by use of special calculation 

techniques may also exist. Since the basic physical 

principles are the same in the impulse and continuous sound 

techniques the approach is identical, but the calculations may 

differ because different algorithms are applied. 

STANDARD NOSE 

A standard nose is a circular tube with an area-distance function 

equivalent to that of a normal nose. The purpose of the model 

nose is to provide simple means to test the equipment for 

acoustic rhinometry. After optimisation of the equipment a 

measurement of the standard nose should be performed to ensure 

a satisfactory function of the equipment. The measurements 

should be stored for later documentation of proper function. 

The standard nose can be used for repeatability tests and 

training new operators. Data for the test nose used here are 

given in the APPENDIX I of this document. Standard noses for 

children and laboratory animals should also be considered. 

TESTING ACCURACY AND REPEATABILITY 

A way to describe accuracy and repeatability is described below. 

A plastic model with circular areas and a known area-distance 

function based on a recording from a normal nose was constructed 

and measured (standard nose, see the appendix for the 

data). The left panel of Figure 1 shows the curve for the model 

(true areas), and the mean measured curve +/- 2 SD. The right 

panel of Figure 1 shows the repeatability of the measurements 

described by the coefficient of variation of 10 measurements. It 

is seen that the coefficient of variation increases considerably 

with distance. A single number for the repeatability is the mean 

coefficient of variation over the entire distance, which is 1.15%.

Recommendations for operations 5 

Table 1. Repeatability of selected parameters for standard nose and step model. 

Standard nose (nosepiece = 4.5 cm)(compare with Figures 1 and 2) 

Volume (cm 3 ) Volume (cm 3 ) Amin Distance to Amin 

0-5 cm 2-5 cm (cm 2 ) (cm) 

True value 1) 4.54 3.02 0.45 1.87 

Measured mean (SD) 2) 4.55 (0.05) 2.93 (0.03) 0.47 (0.003) 1.86 

Repeatability 3) 0.05 0.03 0.003 0.000 

Repeatability % 4) 1.09 1.02 0.64 0.000 

Error 5) 0.01 -0.09 0.02 -0.01 

Error % 6) 0.22 -2.98 4.4 -0.54 

Accuracy % 7) 99.8 97.0 95.4 99.5 

Step model (nosepiece = 3 cm)( compare with Figure 3) 

Volume (cm 3 ) Volume (cm 3 ) Amin Distance to Amin (cm) 

0-5 cm 2-5 cm (cm 2 ) 

True value 1) 5.22 3.30 0.38 1.19 

Measured mean (SD) 2) 4.49 (0.04) 2.75 (0.03) 0.37 (0.003) 1.86 

Repeatability 3) 0.04 0.03 0.003 0.000 

Repeatability % 4) 0.89 1.09 0.81 0.000 

Error 5) -0.73 -0.55 -0.01 0.67 

Error % 6) -14.0 -16.7 2.63 56.3 

Accuracy % 7) 86.0 83.3 97.4 43.7 

1) 

2) 

3) 

4) 

5) 

6) 

7) 

True value: calculated from the dimensions of the model. 

Measured values: mean and SD for 10 measurements. 

Repeatability: SD of measurements. 

Repeatability %: 100*SD of measurements divided by mean of measurements (= coefficient of variation). 

Error: Measured value minus true value. 

Error %: 100*Error divided by true value. 

Accuracy %: 100 – (numerical Error %). 

The accuracy, which is the difference between the model curve 

and the mean measured curve (= the error), is described in 

Figure 2. The accuracy decreases as the distance from the 

beginning of the nasal model/cavity increases. 

The mean accuracy provides a single number for the overall 

accuracy. In the given example it is 0.022 cm 2 . It is seen that the 

numerical value of the percentage error is less than 0.1 cm 2 or 

10% (whichever is the greatest) (Figure 2, right panel). The 

method presented offers a possibility for standardised comparisons, 

but comparison can only be of value if a standard model is 

chosen. The advantage is that it offers a quantitative as well as 

qualitative evaluation of accuracy and repeatability, and the 

more demanding the model is the more informative the results 

will be. Figure 3 shows the accuracy of a step model measured 

with the same equipment. An offset of the initial area and a 

change of the value for the speed of sound (which is used to 

determine the distance) in addition to modification of the software 

can adjust the mean error considerably for a step model, 

but the plot of the area-distance curve of a more “nose like” 

model or a straight tube may then show less accuracy. Accuracy 

and repeatability of selected parameters for the standard nose 

and the step model are given in Table 1. 

That the values presented in Table 1 may provide reasonable 

basis for standardisation requirements are supported by a study 

(Parvez et al., 2000a) in this supplement. They showed an average 

accuracy of 99% in a study of 2 different acoustic rhinometers 

(same manufacturer), where frequent measurements of a 

nose model were performed over periods as long as 18 months. 

Here it is also important to evaluate the results of accuracy and 

reproducibility tests in the light of the actual set-up of the equipment 

(Fisher et al., 1994). 

A study comparing the transient and continuous noise method 

did also show reasonable accuracy of both equipments (Djupesland 

et al., 1999). 

CAUSES OF ERROR 

The influence of external noise on the reproducibility and accuracy 

of the measurement should bedocumented as well as the 

influence of the environmental temperature (see standard operating 

procedures). Data (Djupesland and Lyholm, 1998a, Parvez 

et al., 2000a) suggest that increase in noise level from 60-74 dB 

causes a 5 to 10 fold increase in CV %. Temperature changes 

will change the sound velocity, and therefore also the recorded 

distance. The change is estimated to be about 0.4 mm 0 C (Dju-


Figure 2. The left panel shows the accuracy curve for standard nose (true areas) as function of distance. The right panel shows the difference between 

the model curve and the mean curve (= the error). The “trumpets” define error limits for numerical errors less than 0.15 cm 2 or 15% (whichever is larger), 

less than 0.10 cm 2 or 10 %, and less than 0.05 cm 2 or 5%, respectively. 

pesland and Lyholm, 1998a), but is proportional to the distance 

from the nostril. Other errors may be due to change of position 

of the sound tube (Fisher et al., 1995a; Parvez et al., 2000a) and 

sound leaks at the nostril, which depend on the fit of the nosepiece 

and use of sealing material. Pressure changes arising 

during breathing and swallowing may cause errors by influencing 

the microphone (Djupesland and Lyholm, 1998a; Thomkinson 

and Eccles, 1995) and in some cases the sound generator. 

Improvement of the measurements (decrease of variability and 

increase of accuracy) may be obtained by making an average of 

single rapidly made measurements. Normally, curves with 

obvious artefacts are discarded, and the result is taken as the 

mean of a number of accepted curves. In order to avoid systematic 

within-measurement errors mostly originating at the nostrils, 

either by sound leaks or by deformation, repeated application 

of the nosepiece should be done, preferably without 

observing the screen, and the result given as a mean of such 

repeated measurements. Curve rejection algorithms may be 

used to reduce variability. If used the general principle of the 

algorithm should be specified. Using acoustic rhinometry, 

quality control should be done regularly, to check the whole 

measuring procedure, e.g. as shown in Figure 4. 

NOSE ADAPTORS 

An important aspect in the use of acoustic rhinometry is the 

connection between the measuring tube and the nose (Schmäl 

and Deitmer, 1993). This connection should be tight without 

the possibility of leakage of sound. On the other hand a firm 

pressure from the outside on the nostril and the vestibulum will 

affect the anterior part of the nose, especially the valve region. 

‘Conical nose adaptors’ (nosepieces made of plastic test vials 

with different sized holes in the bottom) have been used but 

nosepieces have been developed which are anatomically more 

correct. It has been shown that the deformation of the vestibulum 

by the anatomical nose adaptor is less than by the conical 

nosepiece inserted into the nostril (Fisher, 1995b). Use of a rim 

of gel on the anatomical nose adaptor has also been shown to 

improve the connection between the anatomical nose adaptor 

and the nostril and to significantly improve the speed, precision 

Figure 3. Repeatability and accuracy for a step model. 

Figure 4. A proposed schedule to check the equipment.


Table 2. Minimum recommendations for acoustic rhinometry for measurement in the standard nose. 

Variable Range Accuracy/resolution Repeatability (10 measurements) 

Distance (excl. nosepiece) 0-10 cm better than 2 mm 

Area (dist. 0-10cm) 0-10 cm 2 better than 0.10 cm 2 or 10% c.v. less than 5 % 2) 

(whichever is bigger) 1) 

Volume (0-5 cm) 0-20 cm 3 less than 2% deviation 3) c.v. less than 2% 3) 

Minimum area Better than 0.05 cm 2 or 5% c.v. less than 2% 3) 

(whichever is bigger) 3) 

1) see Figure 2b. 

2) see Figure 1b. 

3) see Table 1. 

c.v.: coefficient of variation 

and reproducibility of measurements (Parvez et al., 2000a). The 

examiner should focus on achieving an optimal connection. In 

certain situations where the vestibulum and valve area are of 

minor interest and the main purpose is to assess changes of the 

mucosa, the conical nosepiece may be used. The anatomical 

nose adaptors have been developed for use in the right and left 

side separately. If equivalent results or better (regarding repeatability, 

accuracy and risk of errors) can be obtained by one nose 

adaptor for use in both sides this may be preferred. This may 

also minimize the risk of erroneous connection between the 

sound tube and nosepiece. Special nosepieces are recommended 

for use in infants and children. 

Documented results of repeatability, accuracy from nose model 

studies and sources of errors should be stated by the manufacturer. 

RECOMMENDATIONS FOR MANUFACTURERS 

It is recommended that the manufacturer give information 

about: 

• Accuracy and repeatability when used with defined nose 

models. 

• Resolution: may be given in terms of lowpass filter frequency, 

cut off frequency, sampling frequency and measurement 

range or the total transfer function e.g. depicted graphically. 

• Calibration, testing, and adjustment procedures (straight 

tube, standard nose model). 

• General maintenance. 

• Hygiene precautions. 

• Environmental condition limits during measurement (temperature, 

noise etc.). 

• Safety standards conforming to regulations (should be specified 

e.g. FDA approval). 

Explicit warning should be given that equipment using a spark 

to generate a sound pulse should never be used in subjects 

breathing explosive gases. 

The spatial resolution is important because it influences the 

quality of the measurement. The filtering frequency of the lowpass 

filter and sampling frequency may be specified because it 

influences spatial resolution. It is also recommended that the 

manufacturer provides a nose model and a curve of its true 

dimensions to be displayed on the screen for comparison with 

measurements. 

Equipment performance data should be available with regard to 

the standard nose. The influence of temperature on distance as 

well as area should be specified. Influence of noise should also be 

explained. It is the responsibility of the manufacturer that the 

equipment complies with international safety standardslike IEC 

601-1. The manufacturer should supply a detailed users guide. 

To ensure a reasonable technical standard (year 2000) equipment 

performance should be stated as in Table 2. The user 

should make a schedule to check the equipment, in accordance 

with Table 3. 

EQUIPMENT FOR CHILDREN AND ANIMALS 

In small cavities a higher resolution can be obtained because 

higher frequencies of the sound spectrum can be used before 

cross-modes (non-planar waves) start to appear. The measurement 

of the area-distance function by acoustic rhinometry is 

affected by the size of the cavity, which is being measured. In 

small cavities it is possible to increase the low pass filtering frequency, 

and if the microphone has a sufficient frequency 

response the resolution can be improved. The equipment can 

therefore be optimised when used with children and animals. It 

is recommended that the manufacturer documents repeatability 

and accuracy for measurements of standardised nose models 

for children and specifies at which range (e.g. area) a certain 

hardware or software set-up works optimally. For publication of 

the results the specific set-up should be specified (Buenting et 

al., 1997a, b, c; Djupesland and Lyholm, 1997; Pedersen et al., 

1993; Riechelmann et al., 1993). Special aspects of acoustic rhinometry 

in infants and children have been addressed in an 

accompanying paper (Djupesland and Pedersen, 2000). 

VARIABLES DERIVED FROM THE AREA-DISTANCE CURVE 

Acoustic rhinometry measures the cross-sectional area as a 

function of distance into the nasal cavity. The total area-distance 

curve contains information about the geometry of the 

nasal cavity. Therefore, like in an X-ray or in rhinomanometry,


the best way to evaluate the results is to consider the total picture 

or the entire curve rather than single values. Some areas in 

the nasal cavity are more related to the feeling of nose obstruction 

than others. Nasal obstruction is generally located to the 

anterior part of the nasal cavity whereas the posterior part only 

affects the feeling of obstruction to a minor degree. In rhinomanometry 

the location of the main pressure drop, and in 

acoustic rhinometry the narrowest part of the nasal cavity is 

usually situated within a distance of 30 mm from the nares. Two 

minima have been described in this region the I-notch (isthmus 

area) and C-notch (concha, anterior part of the inferior turbinate) 

(Lenders and Pirsig, 1990). The areas of the nasal cavity 

measured in the posterior part of the nasal cavity and the rhinopharynx 

may be affected by the opening to the paranasal 

sinuses especially the maxillary sinus (Hilberg and Pedersen, 

1994). This is an important finding, and should not be considered 

as noise in the measurements. It is recommended that the 

two first minimum areas and their distances from the nostril 

should be measured. One of these areas is most often the absolute 

minimum on the curve, which should be recorded in any 

case together with the nasal cavity volume in the distance from 

0 to 5 cm from the nostril. This will facilitate the comparison of 

results from different studies, and should be independent of the 

maxillary sinuses. For mucosal changes the volume 2-5 seems 

to be an important variable. Schlünssen et al. (unpublished 

observations) examined 175 woodworkers before and after 

decongestion and found decreasing ability to detect effects, ranked 

as follows: vol 2-5 cm, vol 0-5 cm, vol 5-10 cm, and Amin, 

but they were all highly significant. Areas between 5 and 10 cm 

may include information about the sinuses and especially the 

ostia connecting them with the nasal cavity. For daily clinical 

routine it is valuable to print out these variables together with 

the area-distance curve. Other areas and variables may be 

important too e.g. areas at the anterior part of the inferior turbinate 

where the maximum conges-tive capacity of the nasal 

mucosa is located. Also for research the standard variables may 

facilitate comparison of results. Nevertheless more information 

about the relation of the area-distance curve to the anatomical 

structure is needed (Grymer et al., 1991; Gurr et al., 1996; Morgan 

et al., 1995). This is especially true for children, where 

knowledge of the length of the nasal cavity at different ages 

would facilitate evaluation of nasal cavity volume (Djupesland 

Table 3. Quality control (equipment). 

Test 

Standard nose and 

Straight tube 

Calibration check 

Step cavity and straight 

tube 

Software 

Frequency 

Daily 

Weekly and always after corrections and 

interventions 

Always after corrections and interventions 

New versions require full testing and 

comparison with old software 

and Lyholm, 1998b). It is recommended that information 

regarding the equipment and basic variables should be quoted 

when publishing, see Table 4. 

At the moment we have not found any need to standardise how 

the area distance curve should be graphically depicted. Area can 

be displayed on a linear or logarithmic scale, depending on what 

is found most illustrative. 

REFERENCE VALUES 

Normal nasal patency and normal values of the absolute minimum 

area and the nasal cavity volume are not necessarily well 

correlated. The nasal cavity dimension is clearly dependent on 

age but racial differences do also exist (Morgan et al., 1995). For 

the assessment of pulmonary function well-defined normal values 

are described but breathlessness may be seen in patients 

with normal pulmonary function and visa versa. For the nose it 

is even more difficult to define normal values, which can separate 

normal from pathological conditions. The nose may in 

some subjects be almost totally occluded without subjective 

notice. Still, we feel that normal values may help the clinician to 

evaluate the nasal function, especially in case of surgical interventions 

on the nose (Grymer, 2000). APPENDIX II summarises 

reference values from the literature. It is seen that the some 

of the studies have less variability than others probably because 

of more homogeneous populations. In some of the studies the 

normality is defined by a subjective normal nose and by normal 

rhinoscopy and in other studies by a subjectively normal nose 

alone. In some of our data exclusion of the rhinoscopically 

abnormal noses reduced the variation by 20%. We have 

performed an analysis on the data in the appendix looking at the 

minimum cross-sectional area and based on a population size of 

1756. We found the sample size weighted average minimum 

area to be 0.60 cm 2 +/- 0.18 cm 2 (SD). The median was 0.517 

cm 2 and the 5 percentile and 2.5 percentile limits to be 0.360 cm 2 

and 0.320 cm 2 respectively. We believe, based on these results, 

that in a patient complaining of nasal obstruction a minimum 

area below 0.35 cm 2 could indicate that narrowing may play a 

role in the feeling of obstruction. In a normal population there 

will be a number of subjects with smaller areas but without any 

symptoms and there will be patients with wider areas who will 

have symptoms. The large variation is partly due to pooling of 

different races, age, and height, although the latter two factors 

have less influence. Unconfirmed <strong>report</strong>s suggest that the body 

surface-area may be used as a confounder. This may also be 

true for head circumference. As seen in the Table some of the 

small studies show more uniform results, which indicate that 

local reference values may be of some value. 

GUIDELINES FOR OPERATING PROCEDURES 

In different publications and in unpublished observations it has 

been demonstrated that the way the equipment is handled 

during the measurement is important for both accuracy and 

reproducibility (Parvez et al., 2000; Roth et al., 1996; Sipilä et al., 

1996; Tomkinson and Eccles, 1995, 1996). For that reason the


Committee has discussed guidelines for the use of the acoustic 

rhinometer (operating procedures). In this presentation we confine 

ourselves to the outlines. All operators should handle the 

equipment in a standardised way. We recommend that each 

department that uses acoustic rhinometry develop a training 

program for operating personnel. This should include evaluation 

of test variability in both models (e.g. the standard nose) 

and decongested subjects. The coefficient of variation for intratest 

determination of nasal volume in decongested subjects 

should not exceed 5% for repeated measurements in a subject. 

Parvez et al. (2000) found in a factorial study of non-decongested 

normals, variability (CV) of approximately 5% for trained 

operators, which was even lower (2.9%) when special tools were 

used to control sources of error. Twenty hours of intensive 

training was also shown to improve intra-test repeatability to 

within 5% in non-decongested subjects. 

Standardised instructions for the patient with regard to breathing 

(Kesavanathan et al., 1995), positioning of the probe and 

nose adaptor should be developed. Devices to aid correct positioning 

of the nose adaptor should not interfere with the measurements 

(by for example applying pressure to the skin) 

(O’Flynn, 1993). Glasses should be removed before measurement 

to avoid external pressure on the nose. Positioning of the 

sound tube with regard to the nose by a laser pointer mounted 

on the sound tube may also affect the variability of repeated 

measurements (Parvez et al., 2000a). With regard to acclimatisation 

of the subject the recommendations for rhinomanometry 

should be followed (Clement, 1984) since it is already well 

described that external factors may affect nasal patency (Cole et 

al., 1980). It is important to ensure stable, well-defined measurement 

conditions for room temperature and humidity to 

obtain reproducible results (Fisher et al., 1995a,b; Lundqvist et 

al., 1993; Tomkinson and Eccles, 1996; Yamagiwa et al., 1990). 

Acoustic rhinometry can be used to measure changes in the 

congestion of the mucosa and record skeletal abnormalities. As 

the state of the mucosa varies with the degree of the congestion, 

baseline values may vary from day to day. It is therefore advisable 

in studies of the mucosal behaviour during different treatments 

to include measurements with fully decongested mucosa 

to serve as a more stable baseline for comparison. The decongestion 

of the mucosa should be done in a standardised way by 

e.g. nasal decongestant spray repeated after 5 minutes (and 

readings taken after the full effect of the drug is achieved approx 

15 minutes). A summary of the standard operating procedures 

is shown in Table 5. 

Table 4. Description of results for publication. 

Equipment: 

Manufacturer, equipment type, software version etc. 

Sampling rate and filtering frequency (or resolution) 

Measurement: 

Volume 0-5 cm (for mucosal changes 2-5 cm) 

Two smallest minimum areas and the distance from the nostrils to the areas 

within the first 5 cm. 

APPLICATION OF ACOUSTIC RHINOMETRY 

Nasal challenge is just one of several applications of acoustic 

rhinometry. So far no international agreement has been obtained 

regarding how to perform a nasal challenge test. A recent 

paper summarises different measurement techniques (Malm et 

al., 2000) but no precise guidelines and recommendations are 

given. Irrespective of which method is used it is advocated that 

the reproducibility of the test is documented. Repeated challenge 

may change the response due to influx of cells to the 

mucosa. A severe occlusion during the challenge may affect the 

accuracy of the measurement especially in the posterior part of 

the nasal cavity (Nielsen et al., 1996). It should always be noted 

that accuracy decreases with the distance in the nose (Ming and 

Jang, 1995). Effects of decongestive drugs and posture have also 

been examined (Fouke et al., 1992; Kase et al., 1994). In this 

supplement, application of acoustic rhinometry in different settings 

have been described: Parvez et al. suggest nasal histamine 

challenge as a model to induce congestion for pharmacological 

testing (Parvez et al., 2000b). Examining allergy and effects of 

indoor climate is another important area, which has been examined 

by Wålinder et al. (2000). The clinical application of 

acoustic rhinometry in an ENT-department has also been 

described in this supplement (Grymer et al., 2000). A paper 

summarizes the comparison to rhinomanometry and suggests 

that the two methods at present are complementary (Cole, 

2000). It is not the purpose of this presentation to discuss different 

applications of acoustic rhinometry and it should be emphasized 

that technical development is a continuous process. 

Table 5. Standard operating procedures. 

A. Check equipment (see Table 3) 

B. Patient/subject dependent conditions 

The subject should rest and acclimatize for 15-30 min before measurement. 

The subjects should be informed about the procedure, e.g. stop breathing, 

in accordance with the instructions from the manufacturer. 

C. Environmental conditions 

Room temperature Measurements should be made at a constant temperature. 

If room temperature is liable to vary during 

the day, extra calibrations may be required. 

Background noise If background noise exceeds 60 dB, measurements 

may be disturbed (refer to the specification from the 

manufacturer). Relative air humidity should be at a 

constant level or recalibration may be necessary. 

D. Operator dependent conditions 

Proper use of the nosepiece: 

- A tight fit to avoid no leakage should be ensured e.g. by a seal of gel 

(anti-allergenic). In the anatomical nosepiece the opening must be 

equal or larger than the opening of the nostril. 

- Distortion of the nostril should be avoided. 

- The same type of nosepiece should always be used in follow up measurements. 

The operator must train measuring in models and subjects to ensure high 

reproducibility according to the recommendations. 

E. Curve selection procedures. 

F. Perform measurement again if necessary.


FUTURE RESEARCH 

Standardisation is a continuing process and should take into 

account the technical development and the increasing understanding 

of what is measured. For acoustic rhinometry it is 

important to understand better how the nasal cavity geometry 

influences the measured values. It is clearly seen in Figure 3 

that steep changes cause underestimation of the area. We know 

that the area behind a severe constriction is underestimated, but 

we do not yet know how to correct for this. A second important 

aspect is to develop an optimal nosepiece that is easy to use and 

well accepted by the patients. We believe that most of the variability 

is caused by an unsatisfactory coupling of the nose to the 

sound tube. 

We do not know much about antropometric data that correlate 

with nasal cavity dimensions. Height and age do not explain 

much variation (see e.g. references in appendix II). In children 

head circumference seems to be the best (Djupesland and 

Lyholm, 1997). Whether this is true also for adults has not been 

examined. Body surface area is correlated to metabolic rate and 

hence ventilation. It is suggested that body surface-area may be 

related to nasal cavity dimension. More information is needed 

about this. With regard to volumes and areas at predetermined 

distances into the nasal cavity, these figures will depend on the 

length of the nasal cavity, and comparisons are only valid for 

cavities with the same length. This may be a problem in comparison 

of values from men and women and in growing children. 

It should be examined whether the area distance-function contains 

information about the length of the cavity to be used in 

definition of the nasal cavity volume. 

The condition of the mucosa depends on the sympathetic tone. 

In epidemiological studies with measurements under varying 

conditions, simultaneous measurement of changes in pulse and 

blood pressure may possibly be of value as confounders of environmental 

changes. 

CONCLUSION 

It is not the purpose of this document to give guidelines for 

when to use acoustic rhinometry, but it should be noted that 

acoustic rhinometry offers the possibility of an objective evaluation 

of the nasal airway passage both for diagnostic and monitoring 

purposes, and that many studies indicate that it is difficult 

to give an exact evaluation of the nasal patency by rhinoscopy. 

An objective evaluation of nasal patency to improve diagnostic 

accuracy and evaluation of treatment effects could easily be 

implemented in clinical evaluation. For legal reasons an objective 

measurement of nasal patency may also be valuable. 

As mentioned in the introduction, technical development continues 

and accordingly new recommendations may be required. 

A more final solution with regard to the nosepieces is wanted 

and it is suggested that the manufacturers modify the anatomical 

nosepiece so it can be used in both sides and that nosepieces 

for children are developed. The use of nasal challenge 

test in daily routine is still not clarified. 

ACKNOWLEDGEMENTS 

The participants in the Committee on Standardisation of 

Acoustic Rhinometry and working groups are thanked for their 

proposals and comments on the paper. I. Teereehorst is especially 

acknowledged for reviewing the paper and valuable suggestions 

for changes. Rhinometrics is thanked for having the 

standard nose produced based on given data. Niels Trolle 

Andersen is thanked for the statistical analysis. The preliminary 

paper was presented in a committee meeting held at the ERS 

congress in Vienna on 31 June 1998. The final version of the 

paper was presented in a committee meeting held at the ERS 

congress in Barcelona on 25 June 2000. 

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O. Hilberg 

Institute of Environmental and Occupational Medicine 

Vennelyst Boulevard 6 

University of Aarhus, 

DK-8000 Aarhus C 

Denmark 

FAX: +45-8942-6199 

E-mail: oh@mil.au.dk


APPENDIX I: STANDARD NOSE VALUES 

Distance (cm) Diameter (cm) Area (cm 2 ) 

0.000 1.17 1.07513155 

0.172 1.17 1.07513155 

0.344 1.17 1.07513155 

0.516 1.17 1.07513155 

0.688 1.17 1.07513155 

0.860 1.17 1.07513155 

1.032 1.17 1.07513155 

1.204 1.17 1.07513155 

1.376 1.17 1.07513155 

1.548 1.17 1.07513155 

1.720 1.17 1.07513155 

1.892 1.17 1.07513155 

2.064 1.17 1.07513155 

2.236 1.17 1.07513155 

2.408 1.17 1.07513155 

2.580 1.17 1.07513155 

2.752 1.17 1.07513155 

2.924 1.17 1.07513155 

3.096 1.17 1.07513155 

3.268 1.17 1.07513155 

3.440 1.17 1.07513155 

3.612 1.17 1.07513155 

3.784 1.17 1.07513155 

3.956 1.17 1.07513155 

4.128 1.17 1.07513155 

4.300 1.17 1.07513155 

4.472 1.17 1.07513155 

4.644 1.168721569 1.07278329 

4.816 1.113312417 0.97347317 

4.988 1.011889249 0.80418477 

5.160 0.992895576 0.7742782 

5.332 1.025353982 0.82572898 

5.504 1.050781494 0.8671909 

5.676 1.065686385 0.89196685 

5.848 1.033902662 0.83955507 

6.020 0.958210371 0.72112677 

6.192 0.866882797 0.59021555 

6.364 0.792659048 0.49347224 

6.536 0.756531035 0.44951416 

6.708 0.765049443 0.45969406 

6.880 0.81299118 0.51911258 

7.052 0.885646854 0.61604303 

7.224 0.963099522 0.72850446 

7.396 1.029275097 0.83205649 

7.568 1.080154195 0.91635002 

7.740 1.122137557 0.98896763 

7.912 1.161667788 1.05987287 

8.084 1.19643761 1.12426838 

8.256 1.215958669 1.16125476 

8.428 1.211231845 1.15224397 

Distance (cm) Diameter (cm) Area (cm 2 ) 

8.600 1.185177829 1.10320677 

8.772 1.153805197 1.04557421 

8.944 1.13786893 1.0168909 

9.116 1.153631095 1.04525869 

9.288 1.20802157 1.14614419 

9.460 1.296621397 1.32043264 

9.632 1.402175621 1.54416856 

9.804 1.495592187 1.75677546 

9.976 1.544664219 1.87395024 

10.148 1.531071751 1.84111522 

10.320 1.463570537 1.68235327 

10.492 1.373502353 1.48166048 

10.664 1.297155678 1.32152104 

10.836 1.261457195 1.24978388 

11.008 1.279967114 1.28673023 

11.180 1.354306278 1.4405345 

11.352 1.475089764 1.70893986 

11.524 1.621506064 2.06503319 

11.696 1.763591288 2.44278796 

11.868 1.871983407 2.75228797 

12.040 1.932713603 2.93376206 

12.212 1.954729337 3.00098029 

12.384 1.961872441 3.02295314 

12.556 1.976933963 3.06954642 

12.728 2.010964991 3.17613462 

12.900 2.062450599 3.34085011 

13.072 2.122820524 3.53929235 

13.224 2.182735032 3.74189777 

13.416 2.235481213 3.92493013 

13.588 2.277732321 4.07469635 

13.760 2.31055555 4.19297922 

13.932 2.341730008 4.30688746 

14.104 2.386452933 4.47296632 

14.276 2.462789586 4.76370104 

14.448 2.581980079 5.23595199 

14.620 2.737904918 5.8874415 

14.792 2.902608005 6.61708416 

14.964 3.035553197 7.23711673 

15.136 3.107387897 7.58369435 

15.308 3.120033029 7.64554175 

15.480 3.106942879 7.58152234 

15.652 3.100818764 7.55166382 

15.824 3.169944152 7.89210952 

15.996 3.236659958 8.22780578 

16.168 3.250037588 8.29595999 

16.340 3.249992855 8.29573162 

16.512 3.250000929 8.29577284 

16.684 3.25 8.2957681 

16.856 3.249999872 8.29576745 

17.028 3.25 8.2957681


APPENDIX II 

The tables describe data from normal subjects obtained by acoustic rhinometry. The data has mainly been selected from a medline search and the quality has not been evaluated. The list is not exhaustive and 

new data may have been published after the search. A statistical metaanalysis has been performed (see main text) to establish a confidence interval for a normal nose. Not all the papers have been included into 

this analysis because the minimum area or the age of the subjects has not been clearly defined. 

Abbreviations: CSA: cross-sectional area, MCA: minimum cross-sectional area, TMCA: sum of MCA on left and right side. 

Reference values for acoustic rhinometry (year 2000) 

AUTHOR POPULATION MEASUREMENT VALUES Details 

Year/Journal Average (SEM /SD/ Range ) Conclusion 

Sample / Race/s Age, Sex, Non decongested Decongested 

Selection Country Height, Weight 

Adults CSA-cm 2 Vol,cm 3 CSA-cm 2 Vol, cm 3 

Distance to MCA Average-L,R Distance to MCA Average-L,R 

Average of L,R Average of L,R 

Burres SA 72 Asian 21-58 yrs Min CSA(SD) – Min CSA – Impulse method 

1999 28–Asian Controls Asian: 0.59 (0.16) 0.68 (0.16) conical 

Am. J. Rhinol. 16–Vietnamese USA F:20 Control: 0.53 (0.20) 0.60 (0.19) nosepieces 

8–Korean, M:8 Asian, 

4Thai caucasians 

44–Controls: similar 

16 Hispanics, pre&,post 

28 Caucasians decongestion. 

Corey JP 106 4 racial gps 18–57 yrs Min CSA/SD Vol 0–6 cm Min CSA Vol 0–6 cm Two 

et al Asian, black, microphone 

1998 Asian 24 white, hispanic Asian Asian Asian Asian Regression 

Otolaryngol. 0.53(0.10) 7.92(3.14) 0.61(0.12) 11.67(2.81) lines for 

HeadNecksurg Black 22 USA Black determination 

Black Black 0.81(0.11) Black of minimum 

White 53 0.67(0.10) 8.94(2.3) 13.06(3.18) cross–sectional 

White area in different 

Hispanic 7 White White 0.64(0.12) White races based on 

0.52(0.12) 8.25(5.23) 11.90(4.40) sex height and 

weight 

Values for 3 

minimums are 

given 

Grymer et al 198 Caucasian 18–73 yrs Area at 3.3 TMCA/SEM Impulse method 

1997 Denmark M: 2.34(0.08) M: 1.78(0.04) 

Rhinology F: 2.38(0.08) F: 1.64(0.04) 

TMCA 

M: 1.37(0.03) 

F: 1.28 

(0.03)


Grymer LF 82 Caucasian 18–40 yrs TMCA/SEM Upto 7cm TMCA Upto 7cm Impulse method 

et al Random, Denmark 28 yrs All: 1.46 (0.03) Total 1.88 (0.03) 31.0 (0.57) 

Subjectively and F: 1.49 (0.05) 22.6 (0.55) 1.91 (0.05) 31.6 (0.96) Conical nose 

1991 rhinoscopically F: 34 M: 1.43 (0.04) 24.0 (0.81) 1.86 (0.05) 30.6 (0.70) adaptors. 

Rhinology normal 169 cm CSA3.3 21.6 (0.71) CSA3.3 

63 Kg All: 2.63 (0.09) 4.29 (0.12) Nasal CSA 

F: 2.97 (0.12) 4.51 (0.17) increases in A–P 

M: 48 M: 2.52 (0.12) 4.14 (0.16) direction. 

182 cm CSA 4.0 CSA 4.0 

78 Kg All: 3.08 (0.09) 5.15 (0.13) Min CA located 

F: 3.23 (0.13) 5.17 (0.23) anteriorly, after 

M: 2.97 (0.11) 5.14 (0.14) decongestion it 

CSA 6.4 moves to 

All: 4.58 (0.18) 6.18 (0.16) ostium 

F: 5.37 (0.27) 6.69 (0.27) internum. 

M: 4.03 (0.21) 5.81 (0.19) 

Gurr P 40 Indian 18–62 years Min CSA(SD) 0–4 cm Min CSA 0–4 cm Impulse method 

et al 20/ racial group Anglo–Saxon Equal male& female Indian: 0.70 (0.16) Indian Indian: 0.76 (0.22) Indian conical nose– 

1996 asymptomatic, UK in each group Anglo–S: 0.71 (0.15) 4.52 (1.14) Anglo–S:0.77 (0.16) 4.88 (1.21) pieces, 

Rhinology clinically normal. Indian Anglo–SAnglo–S 

39.1 yrs., 1.66 m Distance to MCA, cm 4.7 (0.83) Distance to MCA, cm 5.59 (0.71) Anglo–Saxon 

63 Kg Indian: 1.34 (0.63) Indian: 1.07 (0.52) and Indian 

Anglo–S: 1.16 (0.69) Anglo–S: 0.99 (0.69) noses are 

Anglo–Saxon similar 

33yrs, 1.7 m Mean CSA (0–6) cm Mean CSA (0–6) cm 

70 Kg Indian: 1.46 (0.35) Indian: 1.58 (0.40) 

Anglo–S: 1.46(0.32) Anglo–S: 1.77(0.25) 

Marquez 100 Caucasian Age 37.9 yrs Min CSA(SD) Volume0–7 Min CSA Volume0–7 

Dorsch F Spain Height 167 cm 0.68(0.13) 9.55(1.98) 0.78(0.15) 12.84(2.59) 

et al 0.44–1.17 5.61–15.93 0.46–1.23 6.53–19.67 

1996 distance distance 

ActaOtorrino 1.41(0.92) 0.67(0.67) 

Laringol.Esp. 0.12–2.8 0.12–2.32 

Ma Y, Yu D 176 Asian Distance to MCA MCA(SD) Vol 0–6 cm Continuous 

China 2.22(0.35) 

1997 in 82.7% 0.55 (0.13) 7.16 (1.8) 

0.79(0.25) 

Chun Hua Erh in 17.3% 

Pi Yen Hou Ko 

Tsa Chih


Millqvist E 193 adults out of Caucasian 20– 61 yrs MCA(SEM) TMCA(SEM) Significant 

et al 334 subjects Sweden (most narrow side, F: 1.19 (0.04) correlation.– 

1998 unilateral) M: 1.56 (0.04) MCA & nasal 

Am.J.Rhinol. volume 

Age 20–34 Age 20–34 MCA varies 

F:0.50 (0.02) F: 1.19 (0.04) widely 

M0.60 (0.04) M: 1.44 (0.07) 

Age 35–49 Age 35–49 

F:0.51 (0.02) F:1.20(0.05) 

M 0.69(0.04) M:1.70(0.07) 

Age > 50 Age > 50 

F: 0.51(0.05) F:1.21(0.10) 

M:0.58(0.07) M:1.37(0.13) 

Morgan NJ 60 Caucasian 21–60 yrs Min CSA(SD) 0–4 cm Min CSA 0–4 cm Impulse method 

et al 20/ethnic group Oriental Equal M&F in each Caucasian: 0.71 Caucasian Caucasian: 0.77(0.16) Caucasian conical 

1995 Normal, Black group (0.15) 4.7 (0.83) Oriental: 0.78 (0.16) 5.59 (0.71) nosepieces 

Rhinology No symptoms UK Ave Age, Ht Wt Oriental: 0.62 (0.19) Oriental: Black: 0.98 (0.25) Oriental: differences 

No gross Caucasian Black: 0.88 (0.22) 3.86 (0.75) 6.25 (1.08) Stat.sign. 

abnormalities 33 yrs., 1.7 m Black: Distance to MCA cm Black: MCA N>C&O 

infections, 70 Kg Distance to MCA, cm 5.14 (1.09) Caucasian: 0.99(0.51) 6.16 (1.28) D O>C&N 

medications. Oriental Caucasian: 1.16 Oriental: 0.77 (0.61) Vol N&C>O 

34 yrs., 1.62 m (0.69) Black: 0.98 (0.51) Mean CSA MA N>C>O 

56.8 Kg Oriental: 1.49 (0.61) (0–6) Height 

Black Black: 0.98 (0.51) Caucasian influences 

34 yrs., 1.68 m 1.46 (0.32) distance to 

68.8 Kg Mean CSA (0–6) cm Oriental MCA. 

Caucasian: 1.46 1.21 (0.27) Post 

(0.32) Black decongestion 

Oriental: 1.21 (0.27) 1.74 (0.41) O&C are more 

Black: 1.74 (0.41) homogenous, 

Orientals have 

more vascular 

tissue. 

Roithmann A 51 Toronto 16–66 Mn CSA/SEM Vol 0–8 Min area 0.67(0.01) Vol 0–8 Impulse method 

Et al Normal subjects Canada F:20 Min area 0.62(0.01) 12.14(0.03) Distance 2.00(0.12) 15.02(0.03) 

1995 M:31 Distance 2.35(0.01) 

Laryngoscope 

Samolinski B 645 normal Poland 17–74 yrs Area at isthmus nasi Area at Impulse method 

1998 subjects without F: 249 F: 0.493 (0.04) turbinate: Conical nose 

Analiza nasal complaints M: 396 M: 0.537 (0.03) F: 17–25 0.44 adaptors 

wynikow 17–25 F: 82 M: 126 Area at turbinate M: 17–25 0.60 

rynometrii 26–40 F: 82 M: 104 F: 0.493 (0.033 F: 26–40 0.53 

akustycznej na 41–50 F: 48 M: 97 M: 0.6111 (0.05) M: 26–40 0.57 

potrzeby 51 – F: 37 M: 65 F: 41–50 0.49 

diagnostyki M: 41–50 0.62 

rynoalergologic F: 51– 0.52 

znej M: 51– 0.70


Tomkinson A et 51 (data of 48) N. European 18–59 years – Min CSA(SD) – Impulse method 

al Normal nasal Cardiff, UK Ave. 26 yrs. 1.41 (0.38) conical nose– 

1995 history & M:38, F:13 pieces 

Clin.Otolaryn examination. 

Wang Y, 1355 Asian 3-86 yrs Min CSA – 

1997 Chinese 0.192-0.915 

Chung Hua 

Erh Pi Yen Distance 

Hou Ko Tsa 0.3-2.55 cm 

Chih 

AUTHOR POPULATION MEASUREMENT VALUES Details 

Year/Journal Average (SEM /SD/ Range ) Conclusion 

Sample / Race/s Age, Sex, Non decongested Decongested 

Selection Country Height, Weight 

Children CSA–cm 2 Vol,cm 3 CSA–cm 2 Vol, cm 3 

Distance to MCA Average–L,R Distance to MCA Average–L,R 

Average of L,R Average of L,R 

Buenting JE 10 Caucasian TMCA Up to 36.4mm – – Modified AR . 

et al Normal term 0.192 (0.051) 1.758 (0.527) Validation data. 

1994 infants. MCA 

Laryngoscope 0.096 (0.027) 

Djupesland PG 94 Caucasian 37 – 42 wks TMCA Up to 4.0 cm – – Continuous 

et al Healthy term Norway 40.1 wks All: 0.204 (0.052) 1.82 (0.34) method, 

1997 infants F:42 F: 0.193 (0.043) 1.76 (0.29) miniprobe, 

Acta Anterior L, Wt M: 0.213 (0.057) rounded 

Otolaryngol. rhinoscopy 50.5 cm DMCA (cm) Up to 45 mm 'external' 

normal. 3.6 Kg All: 0.76 (0.24) 2.13 (0.38) nosepiece.. 

Head Circ. 35.3 cm F: 0.73 (0.20) 2.07 (0.33) Supine position 

M: 0.79 (0.26) 2.19 (0.26) Only 1 min.in 

M: 48 acoustic curve 

L, Wt of infants. 

51.2 cm TMCA most 

3.7 Kg important 

Head Circ. 35.9 cm determinant of 

airway 

resistance. 

Djupesland PG 39 Caucasian (Neonates and at TMCA Up to 40 mm – – Continuous 

et al Norway 1 year) 0.35(0.10) 2.44(0.55) 

1998 DMCA Significant 

Acta 0.93(0.34) change during 

Otolaryngol first year of life.


Ho WK et al 183 Asian 1–11 yrs MCA Distance to 

1999 3–6 yrs: 112 Hong Kong M–161, F–22 MCA 

J Otolaryngol. Normal breathing All: 0.32 (0.13) All: 1.40 cm 

children 3–6 yrs: 0.32 (0.12) 3–6 yrs: 1.37 

(0.24) 

Kano S et al 17 Caucasian 1–16 m TMCA 0–4 cm Impulse 

1994 Austrialia 0.32 (0.06) total 

Pediatr 2.37(0.56) 

Pulmonol 

Millqvist E 141 children Caucasian 4–20 yrs Narrowest MCA Total MCA Continuous 

et al out of 334 Sweden Age: 0–9 Age: 0–9 Significant 

1998 subjects F: 0.46(0.02) F: 1.14(0.05) correlation – 

Am.J.Rhinol. M: 0.42(0.02) M: 1.05(0.04) MCA & nasal 

Age 10–20 Age 10–20 volume 

F: 0.47(0.03) F: 1.16(0.07) MCA varies 

M: 0.49(0.03) M: 1.19(0.06) widely 

Pedersen OF 27 Caucasian 36–42 wks TMCA Up to 45 mm – – Impulse 

et al Newborns (Australia) 0.229 (0.055) Ave. L ,R technique. 

1994 Oriental DMCA (cm) 1.05 (0.24) Small probe, 

Laryngoscope (Japan) 1.14 (0.47) Total special nose 

104 2.1 (0.39) pieces 

Technique 

suitable to 

pediatrics. 

Riechelmann 35 Caucasian 3–6 yrs MCA Impulse 

Et al Germany 0.29(0.06) Values of 

1993 different 

Clin minimum areas 

Otolaryngol 

Wang Y, 1355 Asian 3–86 yrs Min CSA – 

97 Chinese 0.192–0.915 

Chung Hua 

Erh Pi Yen Distance 

Hou Ko Tsa 0.3–2.55 cm 

Chih

Supplement, 16, 18–28, 2000 

Novel techniques, standardization tools to 

enhance reliability of acoustic rhinometry 

measurements 

L. Parvez, G. Erasala, A. Noronha 

Procter & Gamble Health Care Research and Development Laboratory, Thane, India. 

SUMMARY 

Acoustic rhinometry measurements are influenced by factors related to subject posture, breathing, 

inclination and positioning of the wavetube, leaks and distortion at the nostril - nose 

adapter connection and ambient noise. We present simple techniques to control these errors. 

Thus, gel on contoured nose adapters, shadow tracing to maintain posture, laser homing for 

wavetube alignment, are all integrated into a practical scheme that is easy to implement and 

causes minimum discomfort to subjects. Repeatability improved to below 3% coefficient of 

variation (CV) in non decongested subjects when trained operators used all the techniques 

together viz. gel on nose adaptors, shadow tracing, laser homing. In a factorial experiment, 

repeated measurements were made on subjects over two consecutive days with operator training 

and standardization tools as variables. An analysis of variance identified the most 

important factors to be gel on contoured nose adapters, operator training and control of 

breathing. With gel, the mean CV between readings was 5.8%, measurement time 30.3 seconds. 

The tools, especially gel and shadow tracing, helped untrained operators achieve performance 

levels that were more comparable with trained operators. Reproducible curves could be taken 

rapidly. Thus a significant difference of 31.2 seconds between untrained and trained operators 

reduced to 12.6 seconds using tools. These techniques significantly improve the reliability, 

speed and ease of doing repeated acoustic rhinometry measurements and thus the quality of 

data generated in nasal studies. 

Key Words: standardization tools, acoustic rhinometry, reliability 

INTRODUCTION 

In 1989 Hilberg et al., first described acoustic rhinometry as a 

rapid, non-invasive technique to study the geometry of the nasal 

cavity. The method’s accuracy has been validated in models, 

cadavers and in-vivo studies (Hilberg et al., 1989, 1993; Mayhew 

and O’Flynn, 1993; Min et al., 1995). Model studies have also 

been performed with modified equipment that allows measurement 

in infants (Pedersen et al., 1994a; Buenting et al., 1994; 

Djupesland et al., 1998). 

The technique has gained considerable popularity and numerous 

studies have been published that evaluate effects of surgery 

(examples: septoplasty and rhinoplasty, Grymer et al., 1989, 

1995; Lenders and Pirsig, 1990; sinus surgery, Lund and Scadding, 

1994, etc.), response to nasal challenge (Austin and Foreman, 

1994; Tanaka et al., 1994a; Hilberg et al., 1995), anti-allergic 

and nasal decongestant drugs (Fouke and Jackson, 1992; 

Tanaka et al., 1994b; Mygind et al., 1997; Yamagiwa, 1997). Also 

nasal physiology has been studied (Yamagiwa et al., 1990; Fisher 

et al., 1993) and normative data gathered for different populations 

(Gurr et al., 1996; Corey et al., 1998; Millqvist et al., 1998) 

and guinea pigs (Pedersen et al., 1994b) due to swiftness in 

recording measurements that require minimal co-operation. 

With ever increasing use, it is important to understand the limitations 

of the method. Although the accuracy of the basic 

method has been demonstrated, significant error and artifacts in 

the area-distance curve can result because of improper implementation. 

These have been effectively summarized by Hilberg 

and Pedersen (2000) and are included in the recent recommendations 

of the Standardization Committee on Objective Assessment 

of the Nasal Airway. Investigators have found that leaks 

and distortion at the nostril – noseadapter connection and misalignment 

of the acoustic wavetube in the nasal cavity axis can 

result in substantial inaccuracies and lack of reproducibility 

(Kase et al., 1994a; Roithmann et al., 1995a, 1995b; Fisher 

1995b). Postural effects on nasal patency (Fouke and Jackson, 

1992; OFlynn, 1993; Kase et al., 1994b) also need to be considered 

when using acoustic rhinometry. 

We have examined important factors influencing the reliability 

of acoustic rhinometry and classified these into four categories 

related to the Operator, Subject, Instrumentation and Environ-

Standardization of acoustic rhinometry 19 

Figure 1. Contoured nose adapters showing cut-off angle of 

60 degrees. 

ment. Operator dependant errors include improper connection 

at the nostril producing leaks or distortion, non-reproducible 

positioning and misalignment of the probe in the nasal axis. 

Training and skill of operators in performing correct measurements 

is also a factor. Subjects, by varying their posture and 

improperly controlling breathing during measurements, also 

introduce errors. Rhinometers used have to be well calibrated 

and performance evaluated regularly with respect to a standard. 

Measurements should be made under controlled environmental 

conditions of temperature, humidity and ambient external 

noise. 

This paper discusses the influence of these errors and describes 

simple and inexpensive tools to counter them. These tools have 

been integrated into an easy to use, practical scheme which 

causes minimum discomfort to subjects being measured. Also 

presented are a set of experiments designed to quantify the 

effect of these tools on the repeatability of acoustic rhinometry 

measurements in nondecongested subjects. 

METHODS 

Subjects 

In all, 10 subjects (1 male, 9 females) participated in the experiments. 

They were all healthy with subjectively normal patency 

and no recent infection or other nasal disease. Four of the 10 

subjects (all female) that participated were the same in 2 factorial 

studies designed to separately test the effect of breathing 

and standardization tools. Six other subjects participated in a 

separate experiment to evaluate the effect of training. 

Methods 

The acoustic rhinometer used was the continuous wide band 

acoustic rhinometer (model SRE 2000PC, Rhinometrics, Lynge, 

Denmark). It comprises the master unit that houses the digital 

signal processor used to generate a wide band noise signal. The 

signal transmits through a 58 cm, lightweight wavetube (R-258 

type probe) and is connected to the nostril by the contoured, 

anatomical nose adapter of 5 cm length and cutoff angle of 60° 

(Figure 1). The probe has a microphone in its midsection to pick 

up incident and reflected signals and was hand held by operators 

while taking measurements on all subjects. The system was 

run using accompanying software (version 1.28/1.11) with 

sampling frequency 44 kHz, filtering frequency 10.6 kHz and 

spatial resolution of 0.4 cm in the distance axis. Since our laboratory 

had two identical SRE 2000PC rhinometers, these were 

identified as System 1 & 2, each with its own probe (kept constant 

throughout). System 1 was used in all experiments except 

where the instruments were themselves being compared. 

Some experiments were performed separately to study a particular 

error and are described in the appropriate section, but finally, 

a definitive experiment using a factorial design was conducted 

to help evaluate the usefulness of various combinations 

of tools on the precision, reproducibility and ease of performing 

measurements for both trained and untrained operators. Controls 

were implemented stepwise, using a standardised protocol 

and are described in the sequence used. 

Control of instrumentation 

The performance of the SRE 2000PC (System 1) was carefully 

monitored each working day over a period of 18 months (347 

days in all) and data collected on monthly performance control 

charts. At the start of each day, calibration and system accuracy 

checks were performed using a “Standard Nose” model (Rhinometrics, 

Denmark). The standard nose is a 9 cm teflon cylinder 

having gradually varying circular cross-section along its interior. 

Its dimensions simulate the adult human nasal area-distance 

curve and was based on magnetic resonance imaging data of a 

normal subject. Since actual dimensions (volumes) of the 

model were known, the accuracy of measurements could be 

measured and were monitored over time. Thus, volumes in 

different regions that are generally considered to include prominent 

anatomical features like the nasal valve VOL1 (10 – 32 

mm), turbinates VOL2 (32 – 64 mm) and volume in the first 5 

cm VOL0-5 (0-50 mm) were calculated and data for two SRE 

2000PC rhinometers (System 1 & 2) were compared. 

Control of the environment 

Measurements were performed only after subjects acclimatized 

to the controlled temperature and humidity conditions (24 – 

26 o C, 45-55% RH) in the measurement room for a minimum 

half hour period, in the seated position. Careful attention was 

paid to reduce ambient noise levels in the measurement area to 

below 60 dB. Care was taken to always calibrate the rhinometer 

at the ambient condition prior to measurements. 

Experiment: To investigate the influence of external noise on 

the area-distance curve, an experiment was conducted with two 

different sound pressure levels in the measurement room. A 74 

dB noise level was produced by turning on all air conditioning 

and dehumidification equipment and 60 dB when these were 

turned down (without altering ambient temperature and humidity). 

Sound level measurements were made at the mouth of

20 Parvez et al. 

the wavetube using a decibel meter. The acoustic rhinometer 

was first calibrated at the ambient noise level. At each noise 

level (74 db and 60 dB), three sets of measurements were made 

after detaching and replacing the “standard nose” model (right 

cavity simulation) each time. Each set comprised five successive 

measurements without displacing the model, hence a total 

of 15 area distance curves per noise level. Accuracy and coefficient 

of variation (CV) for the volume upto 5 cm was calculated 

from area distance curves. 

In all subsequent experiments sound level was maintained 

below 60 dB. 

Control of subject posture using a “shadow trace” of the head 

Subjects were seated upright in a comfortable chair for measurements. 

To ensure stable and reproducible posture of the 

head and position in the chair at all timepoints, the shadow of 

the head was matched with an outline traced during the first 

measurement. “Shadow Tracing” was simple to perform using a 

frontally directed, ceiling mounted 50 Watt spotlight at a 6 foot 

horizontal distance from the subject’s chair. The shadow cast 

(in one dimension) was outlined using a pen on an A3 size 

paper mounted on a clipboard with an additional function as a 

comfortable head rest behind the chair. The spotlight was turned 

off during actual measurements using the conveniently 

located switch. It was easily switched on to verify positioning 

and realign the subject with the traced outline when in doubt or 

during subsequent readings (Figure 2). 

Figure 2. Simple standardization tools implemented during acoustic 

rhinometry measurement on a subject. 

1 – Shadow tracing, 2 – Gel on contoured nose adapter, 3 – Trained operator, 

4 – Laser homing 

Control of breathing during measurements 

Since nasal breathing resulted in grossly fluctuating curves and 

difficulty in obtaining reproducible curves in quick succession, 

subjects were instructed to briefly breathhold during measurements 

with the exception of the experiment described below. 

Experiment: To quantify the effect of nasal breathing on the area 

distance curve, 6 operators (equal trained and untrained) measured 

4 subjects who were instructed to control their breathing in 

3 different ways. First, readings were taken with subjects breathing 

naturally i.e. with no instruction regarding breathing technique. 

In the second instance they were specifically instructed to 

actively breathe during measurement and in the third set, were 

asked to breathhold. In each set as many readings as necessary 

to record 3 reproducible (overlapping) area distance curves 

without operator bias were made. Operators were not allowed 

to see acoustic curves being displayed on the computer screen 

which was turned away and monitored for superimposibility by 

a separate trained operator who was not involved with any other 

aspect of the study. The coefficient of variation between all curves 

recorded in the process were calculated along with nasal 

volumes (0-7 cm) and time taken to complete a satisfactory reading. 

These were compared between trained and untrained operators. 

Gel on contoured nose adapters for a distortion and leakfree 

connection to the nostril 

A water based 1% carbopol gel was formulated in our laboratory 

specifically for this application. It was applied as a continous, 

uniform, 2 mm band on the rim of contoured noseadapters, just 

prior to attachment to the nostril of a subject. This 2 mm band 

of gel allowed operators to make the connection to the nostril 

gently and without distortion, while ensuring a good leak free 

seal. The consistency of the gel (viscosity about 30,000 centipoise), 

easy wipeability and convenient dispensing in easy squeeze 

tubes with a 2 mm mouth (nozzle) diameter made application 

rapid, accurate and comfortable to use (Figure 2). 

Laser Homing for reproducible spatial alignment and positioning 

of the wavetube in the nasal cavity axis 

A low intensity Laser pointer (Class IIIa,


ensured by simply coinciding the laser spot with the mark on 

the cheek. Changed posture and head position affects reproducibility 

using this tool and was controlled using the shadow 

tracing technique implemented in a previous step. 

Operator training and skill 

Experiment: Training and measurement skill of 4 operators (two 

trained and two untrained) was evaluated by measuring 6 volunteers 

using all standardization tools. A measurement comprised 

all curves obtained while achieving the target of 3 “superimposible 

curves”, detaching and repositioning the probe to the 

nostril between readings. The coefficient of variation between 

all curves recorded was calculated and compared for trained and 

untrained operators. Trained operators had undergone an intensive 

20 hour practice schedule over a week prior to this experiment. 

New operators were explained technical aspects of the 

system including use of the tools and were allowed to handle 

and have limited practice using the instrument before the experiment. 

In addition to this experiment, trained and untrained operators 

were evaluated in a factorial experiment that also tested different 

combinations of tools. 

Factorial study 

Measurements were made by operators with the acoustic probe 

hand held and subjects briefly holding breath during readings. 

Environmental controls were carefully maintained throughout. 

Trained operators in this experiment had continuous experience 

using the acoustic rhinometer for at least 1 year while untrained 

operators were technical staff members working in unrelated 

fields, with no prior exposure. Untrained operators were 

carefully instructed, provided technical information and time to 

familiarise themselves with the instrument through a few practice 

readings till they felt comfortable to start the experiment. 

Variables analysed were: 

1) time taken to obtain three reproducible or overlapping 

curves without operator bias (area distance curves were not 

visible to operators on screen during measurements) 

2) number of curves recorded 

3) CV between all curves calculated for total airway volume 

upto 12 cm 

4) nasal airway volume upto 7 cm. 

In addition, the alignment of the wavetube in the vertical and 

horizontal plane was determined for every new measurement, 

across factors, subjects and operators. To measure the angle in 

the horizontal plane, a ceiling spotlight cast a shadow of the 

wavetube on a protractor which was appropriately aligned in the 

horizontal plane (across the arms of the chair with subject 

seated). For vertical plane measurements, a plumbline was 

dropped from the wavetube with its fulcrum fixed on a protractor. 

Parallax error in reading angles was avoided by using the 

shadow of the plumbline cast by a frontally placed torchlight 

(Figure 4). 

Figure 3. Study design for the factorial experiment using combinations 

of tools and trained/ untrained operators. 

This study was designed to evaluate the influence of the standardization 

tools (each separately, all tools, none, and different 

combinations) on measurements taken by both trained and 

untrained operators. The 2*4 factorial design examined 4 factors 

viz. gel on contoured nose adapters, shadow tracing, laser 

homing and training each at two levels (present, absent). Six 

operators (three each, trained and untrained) performed acoustic 

rhinometry measurements on 4 subjects each on 2 successive 

days. The order of testing various combinations of factors (8 

in all) were randomly assigned to subjects and operators. In this 

way each operator performed 64 single nostril measurements 

each day, contributing to a total of 768 measurements recorded 

in all (Figure 3). 

Figure 4. Measuring angle of inclination of wavetube in vertical and 

horizontal planes. The subject is seen from the front, the wave tube is 

seen from the side and the laser pointer is seen from above.


Table 1. Instrument Performance: Accuracy and reproducibility of two SRE 2000PC continuous acoustic rhinometers evaluated using the standard nose. 

VOL1Nasal volume from 1 to 3.2cm, VOL2Nasal volume from 3.2 to 6.4cm, 

System 1 System 2 

N=347, Nov’96-May’98 

N=152, Sep’97-Apr’98 

Variables 

Variables 

Vol 0-5 Vol1 Vol2 Vol 0-5 Vol1 Vol2 

0-5 cm 1-3.2 cm 3.2-6.4cm 1-3.2 cm +3.2-6.4cm 

Actual Value 6.138 2.685 4.698 6.138 2.685 4.698 

Measured Value 

- Mean (SD) 6.140 (0.11) 2.622 (0.05) 4.690 (0.09) 6.198 (0.17) 2.628 (0.08) 4.708 (0.17) 

- 

Range 5.7-6.5 2.5-2.8 4.3-5.0 5.4-6.8 2.3-2.9 3.9-5.3 

Precision (%CV) 1.74 1.85 1.99 2.73 3.21 3.68 

Accuracy (%)* 99.1 97.6 99.8 99.0 97.9 99.8 

System 1 versus System2 

% Difference 0.93 0.22 0.37 

* Accuracy (%) : Actual value – Measured value / Actual value X100 

Statistical methods 

The factorial design of this study allows us to optimally test and 

interpret the effect of varying combinations of factors (tools). 

Thus all possible interactions between tools were studied for 

each variable using ANOVA, and significance was ascribed for 

a p-value less than 0.05. 

RESULTS 

1. Instrumentation checks 

Volume measurements of the standard nose model (Rhinometrics, 

Denmark) were used to test the accuracy and reproducibility 

of two SRE 2000PC rhinometers over extended periods 

(18 and 8 months for Systems 1 and 2 respectively). Variability 

(%CV for total volume) across the period was


Figure 6. Sample area distance curves at ambient noise levels of 74 dB and 60 dB. 

Table 2. Influence of ambient noise on acoustic rhinometry measurements 

using the standard nose model. Comparison with actual values 

provided by manufacturer. 

Standard Nose (right cavity) 

Variable : Volume 0-5 cm, cc 

Actual value 6.1 

Measured value 

At ambient sound level 

N=15 curves at each sound 60dB 74dB 

level 

Mean (SD) 6.06 (0.03) 6.15 (0.35) 

Range 6.0 - 6.11 5.6 - 6.84 

Precision (%CV) 0.5 5.6 

variables. Readings on the right nostril were made more rapidly 

and were less variable (Table 5). 

The effect of tools in different combinations were tested and 

some are represented in Table 6. Using all tools together, performance 

measured by variables improved for untrained operators, 

especially in estimation of nasal airway volume where 

differences from trained operators were no longer significant 

(Figure 7). 

In a separate experiment, 20 hours of intensive training could 

reduce variability between curves recorded in each measurement 

set to below 3% (mean CV) compared to approximately 

14% for untrained operators (Figure 8). 

Accuracy % (Mean) 99.3 99.25 

Range 98.4 - 9.8 87.9 - 91.8 

Table 3. Influence of breathing in a factorial experiment using trained and untrained operators. 

Variables 

Mean value (SD) 

Breathing technique Measurement Number of %CV Nasal Volume 0-5cm Nasal Volume 0-7cm 

includes all operators:) Time (sec) Curves Between (cc) (cc) 

trained & untrained 

All Curves 

Breath-hold N=74 23.4 (13.8) 3.7 (2.1) 4.4 (6.0) 4.2 (0.9) 7.2 (1.7) 

Natural (no instruction) N=72 37.7 (23.7) 5.4 (2.1) 8.6 (7.8) 4.6 (1.2) 8.1 (2.3) 

Active Breathing N=70 40.3 (23.4) 5.5 (2.0) 10.3 (9.1) 4.5 (1.1) 7.8 (2.1) 

p-value (ANOVA) 0.0001 0.0001 0.0001 0.04 0.03 

Training 

(includes all breathing techniques) 

Trained N=106 26.9 (19.5) 4.5 (2.0) 6.1 (6.6) 4.3 (0.9) 7.4 (1.8) 

Untrained N=110 40.8 (19.9) 5.3 (2.1) 9.3 (9.0) 4.6 (1.1) 8.0 (2.3) 

p-value (ANOVA) 0.0001 0.003 0.002 0.04 0.05


Figure 7. Comparison of trained and untrained operators using all tools or no tools. 

DISCUSSION 

We have tried to identify specific executional aspects of acoustic 

rhinometry which are prone to error and suggest simple solutions 

to standardize use and improve reliability wherever 

applied. These methods have been integrated into a practical 

scheme: 

1. Performance qualification for rhinometers. 

2. Suitable acclimatization (half hour) in a stable environment 

of temperature and humidity with ambient noise levels 

maintained below 60 dB. 

3. Gel applied to contoured nose adapters for a distortion and 

leak free fit. 

4. Shadow tracing for reproducible posture and head positioning. 

5. Laser homing for wavetube alignment. 

6. Breathhold during measurements. 

7. Operators who have undergone adequate, recent training 

using the acoustic rhinometer and accompanying tools. 

Table 4. Effect of individual standardization tools on precision, speed and accuracy of acoustic rhinometry measurements from a factorial experiment. 

Factors Level Variables – Mean (SD) 

Measurement # of Curves %CV (between Nasal Volume Wavetube Angle 

Time (seconds) recorded curves) 0-5cm Vertical plane Horizontal plane 

Gel No 55.2 (41.7) 6.4 (2.5) 10.9 (8.6) 9.8 (2.8) 43.9 (5.0) 11.0 (6.8) 

Yes 30.3 (21.8) 4.5 (1.8) 5.8 (7.3) 7.6 (2.0) 46.5 (5.0) 9.8 (5.9) 

p value (ANOVA) 0.0001 0.0001 0.001 0.0001 0.0009 0.2 

Shadow No 44.1 (36.4) 5.5 (2.5) 8.9 (9.1) 8.8 (2.9) 45.2 (5.7) 9.9 (6.4) 

Yes 41.4 (34.6) 5.3 (2.3) 7.9 (7.6) 8.6 (2.5) 45.1 (4.7) 10.9 (6.3) 

p value (ANOVA) 0.2 0.2 0.06 0.3 0.8 0.3 

Laser No 42.3 (36.6) 5.3 (2.4) 7.9 (7.8) 8.6 (2.6) 44.3 (5.0) 10.2 (6.3) 

Yes 43.2 (34.4) 5.5 (2.4) 8.9 (8.9) 8.8 (2.8) 45.9 (5.3) 10.7 (6.5) 

p value (ANOVA) 0.7 0.2 0.05 0.3 0.04 0.6 

Training No 54.4 (41.4) 6.2 (2.6) 11.3 (8.9) 9.3 (2.5) 44.0 (5.4) 12.8 (7.2) 

Yes 31.1 (23.1) 4.7 (1.9) 5.5 (7.1) 8.2 (2.6) 46.3 (4.7) 8.0 (4.3) 

p value (ANOVA) 0.0001 0.0001 0.0001 0.0001 0.003 0.0001 

Table 5. Effect of measurement day and nostril on acoustic rhinometry measurements in a factorial experiment. 

Factors Level Variables – Mean (SD) 

Measurement Time # of Curves Recorded % CV (between curves) Nasal Volume 0-5 cm 

Day 1 45.8 (39.6) 5.6 (2.6) 8.9 (8.3) 8.9 (2.7) 

2 39.6 (30.5) 5.2 (2.2) 7.9 (8.5) 8.5 (2.7) 

p value (ANOVA) 0.005 0.002 0.07 0.02 

Nostril Left 44.6 (38.4) 5.6 (2.6) 9.2 (9.7) 8.6 (3.0) 

Right 40.8 (32.2) 5.3 (2.2) 7.5 (6.7) 8.8 (2.3) 

p value (ANOVA) 0.08 0.03 0.001 0.9


Table 6. Effect of tools in combination(s) on precision, speed and accuracy of acoustic rhinometry measurements from a factorial experiment. 

Combinations of Level Variables 

Factors 

Measurement Time (sec) # of Curves Recorded % CV (between curves) Nasal Volume 0-7 cm 

Gel – Shadow Untrained 37.9 (34.6) 4.9 (2.5) 7.5 (9.1) 7.8 (2.4) 

Trained 23.4 (12.8) 3.9 (1.0) 2.8 (2.9) 7.4 (1.8) 

p value (ANOVA) 0.02 0.09 0.002 0.4 

Shadow – Laser Untrained 59.4 (33.7) 7.1 (2.4) 13.2 (5.7) 10.3 (2.3) 

Trained 35.9 (21.6) 5.2 (1.7) 7.1 (4.9) 8.9 (2.3) 

p value (ANOVA) 0.009 0.3 0.0001 0.003 

Gel – Shadow - Laser Untrained 36.6 (17.7) 5.1 (1.8) 9.0 (8.7) 7.7 (2.0) 

All Tools Trained 24.0 (13.8) 4.0 (1.3) 2.9 (3.3) 7.4 (1.7) 

p value (ANOVA) 0.04 0.06 0.0001 0.5 

No Tools Untrained 66.5 (37.6) 7.3 (2.5) 14.1 (7.6) 10.5 (2.5) 

Trained 35.3 (26.1) 5.1 (2.0) 6.7 (6.5) 8.7 (2.5) 

p value (ANOVA) 0.0001 0.0001 0.0001 0.0003 

Instrumentation 

We have tested only the continuous wide band acoustic rhinometer 

which has some different features from rhinometers that use 

an isolated impulse as the incident signal, but the final result 

from a measurement does not differ. This must be considered 

while examining data presented in this paper. Attachment of 

the acoustic probe to the nostril was performed by operators 

who handheld the wavetube. We believe this technique results 

in more reproducible measurements since it ensures a more 

uniform and correct fit and alignment at the nostril, not affected 

by inter and intra-subject variability in positioning and differing 

pressure on nose adapters (especially contoured) than with the 

tube in a fixed position. 

Monitoring performance of instruments over the period of use 

provides positive assurance that results are valid and accurate 

and will be reproducible and comparable across studies and 

different investigators, under similar test conditions. Our data 

using the standard nose showed high accuracy and precision in 

volume estimation which was greater than 98% over long 

periods of study. Also 2 different instruments of the same type 

were very comparable (within 1%). This data supports the minimum 

standards recommended by Hilberg and Pedersen (2000 ) 

for reproducibility and accuracy (Table 1). Checks using step 

cavity models are also recommended for equipment but have 

not been used in this investigation. While not as representative 

of the nasal cavity, the step model helps characterize equipment 

performance and is suited more for evaluating the systems 

response to rapidly changing cross-sections. It should be used to 

test equipment during malfunction and changes which was not 

the purpose of this study and hence was not included. 

Study design aspects 

Experiments were designed, including the 2 4 factorial study to 

test the influence of conditions and tools, both independently 

and in combination. The factorial study was thus well powered 

6 operators X 4 subjects X 2 nostrils X 2 days X 8 factors =768 

measurements) and helped us identify the most important sources 

of error and thus quantify the beneficial effect, if any, of 

remedial measures (Figure 3). 

Subjects were all examined in the non-decongested state. This 

was done to obtain a more realistic estimate of variability since 

the technique has many applications which do not study the 

decongested state. Also, there are few studies <strong>report</strong>ed in non 

decongested subjects (Roithman et al., 1995b) and no recommendations 

have been made as yet for repeatability, reliability 

values in this state (Hilberg and Pedersen, 2000, recommend 


Environmental controls 

It is <strong>report</strong>ed that ambient temperature change alters the speed 

of sound and thus affects acoustic measurements resulting in 

shifts in the distance axis (Tomkinson and Eccles, 1996) but this 

may partly be due to the calibration. Our investigations have all 

been conducted in stable temperature and humidity conditions 

(24 – 26 o C, 45 – 55% RH). 

Ambient acoustic noise can superimpose with the probing signal 

from the other nostril or an open mouth and could be responsible 

for increased variability and waviness in the area-distance 

curve as observed at 74 dB compared to 60 dB from our data 

(Figure 6, Table 2). This is similar to <strong>report</strong>s by Djupesland et 

al. (1998) using an optimised rhinometric probe for infants that 

showed reduced repeatability at sound levels above 60 dB. 

Influence of Breathing 

When subjects breathe through the nose during measurements, 

a slowly varying pressure wave is applied to the sensitive microphone 

in the wavetube. This causes a large fluctuation and 

inconsistency in measurements. Tomkinson et al. (1995) have 

found significant changes in minimum cross sectional area 

during inspiration and expiration (decreased in inspiration and 

vice versa) and recommend a brief breathing pause during 

measurements. Data from our factorial experiment also supports 

the use of the breathhold technique. Compared to active 

breathing or when no specific instructions were given, breath 

hold resulted in significantly faster readings with better repeatability 

and significantly lower measured nasal volumes. The 

over-estimation during breathing may indicate effect of the 

expiratory part of the cycle during which nasal cavity dimensions 

are known to increase. The similarity in data for nonbreath 

hold maneuvers indicates that when not instructed, subjects 

are likely to breathe consciously, indicating that specific 

instructions to pause breathing need to be given during measurements 

(Table 3). 

Influence of tools and training 

Clearly gel on contoured nose adapters and operator training were 

the factors that most significantly improved speed, precision 

and reproducibility of readings. With gel, the time to take readings 

reduced by 45% compared to without (average 55.2 seconds 

reduced to 30.3 seconds), and the mean CV was 5.8% compared 

to 10.9% without gel (Table 4). Thus variability nearly doubled 

and 30% more curves were recorded in the process of obtaining 

satisfactory readings. The same magnitude of differences were 

observed for trained compared to untrained operators. There 

were significantly lower nasal volumes estimated (approximately 

22% and 11% different) using gel or trained operators respectively. 

This suggests loss of acoustic signal due to leaks that lead 

to significant volume overestimation when gel and trained 

operators were not used. 

The need to maintain a leak free nostril-noseadapter interface is 

well known and it is <strong>report</strong>ed that even small leaks can cause 

significant dissipation of the acoustic probing signal and hence 

an overestimation of nasal cross-sectional areas. Our data provides 

quantitative estimates of the magnitude of this error viz. 

22% overestimation of nasal airway volume. This is despite 

using anatomically contoured noseadapters which while serving 

to more effectively juxtapose the surfaces, still needed a reliable 

sealing medium to prevent leaks and facilitate distortion free 

placement. Ideally the medium (gel) should be inert and allow 

fast and easy application, good seal quality and easy wipeability 

from the nostrils. The viscous characteristics of our water based 

carbopol gel are ideal, providing just the right consistency without 

breaks in the band layer or being too thin and likely to drip 

into the nose adapter and cause incorrect readings. 

Spatial alignment of the wavetube can be affected by subject 

posture (head) and the absolute positioning or angle of inclination 

of the acoustic probe in the nasal cavity axis. More complex 

and cumbersome systems including stands, chin supports and 

craniostats (Fisher et al., 1995a; Roithmann et al., 1995a, 1995b; 

Passali et al., 1996) have been used. We adopted the simple 

approach of shadow tracing for reproducible head positioning 

which is unobtrusive and non-interfering with subjects. 

The laser homing device was also activated to further pinpoint 

and reproduce positioning of the probe. A laser beam has the 

advantage of having a small spot size, thus ensuring accurate 

positioning. The holder arrangement can be moved along the 

length of the wavetube and the angle between the laser probe 

and wavetube can be adjusted to allow a spot to fall on the 

cheek of seated subjects. It is safe when used as instructed 

taking care to keep eyes closed during readings and activating 

for brief periods only. We have optimized one position (13 cm 

from open end of wavetube at a 7 o angle) that was suitable for 

all subjects. 

Spatial alignment of the wavetube was found to be reproducible 

with only minor differences (approximately 44 – 46 o in vertical 

and 10 – 11 o in horizontal) irrespective of tool or training. We 

infer that factor/s apart from all those tested are responsible for 

the accuracy in positioning. This could be due to the contoured 

nose adapters with 60 o cutoff angle which when applied to the 

nostril automatically results in proper alignment in the nasal 

cavity axis (Figure 1). Also, operators may quite easily develop 

a “natural” way of handling the probe that results in correct 

alignment especially in the vertical plane. The significantly larger 

difference noted between untrained and trained operators 

for angle in the horizontal plane could reflect very conscious 

and forced attempts by the untrained, which lead to “unnnatural” 

positioning. However, it is to be noted that use of gel, laser 

and trained operators (separately) produced small (2-3°) but 

significant changes in angle of inclination in the vertical plane. 

The results also indicate that the appropriate angle of inclination 

in the vertical plane is approximately 45 o , similar to that 

used by Roithmann et al., (1995a, 1995b) and 8-10 o in the horizontal 

plane. 

Training 

The factorial study clearly demonstrated the benefit of training, 

with performance improvements ranging from 24 – 51% across 

variables (Table 4). For every variable tested untrained operators 

using all tools together performed much closer to trained 

(Figure 7, Table 6). The differences were no longer significant


in estimations of nasal volume. Predictably, maximum variability 

and differences were observed in untrained operators when 

using no tools (e.g. CV between curves 14.1%, measurement 

time 66.5 seconds) compared to the best control being achieved 

in trained operators using all tools (CV 2.9%, measurement time 

24 seconds). Trained operators without tools showed lower 

repeatability values with a CV of 6.7%, double that using tools. 

This emphasises the value of using all tools in the integrated 

way in which it was performed in this investigation. 

In this investigation the overall repeatability of measurements 

in the non decongested state across all factors, averaged 8.9% 

(CV for vol 0-5) on Day 1 and 7.9% on Day 2 (Table 5). This 

compares very closely with Roithmann et al. (1995b) who <strong>report</strong> 

a 9% median variability for total nasal volume. These values are 

higher than the recommended CV of


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44. 

25. O`Flynn P (1993) Posture and nasal geometry. Acta Otolaryngol 

(Stockh) 113: 530-532. 

26. Passali D, Biagini C, Di Girolamo S, Bellusi L (1996) Acoustic rhinometry 

: practical aspects of measurement. Acta Otorhinolaryngol 

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27. Pedersen OF, Berkowitz R, Yamagiwa M, Hilberg O (1994a) Nasal 



28. Pedersen OF, Yamagiwa M, Miyahara Y, Sakakura Y (1994b) Nasal 

cavity dimensions in guinea pigs measured by acoustic reflections. 

Am J. Rhinology 8(6): 299-304. 

29. Roithmann R, Chapnik J, Zamel N (1995a) Reproducibility of 

acoustic rhinometric measurements. American Journal of Rhinology 

9(5): 263-267. 

30. Roithmann R, Cole P, Chapnik J, Shpirer I, Hoffstein V, Zamel N 

(1995b) Acoustic rhinometry in the evaluation of nasal obstruction. 


40. Tanaka T, Kase Y, Okita W, Ichimura K, Iinuma T (1994a) Vasoactivity 

of human nasal mucosa in response to sensory neurotransmitters 

(a study of nasal geometrical change with acoustic rhinometry). 

Nippon Jibiinkoka Gakkai Kaiho 97(7): 1211-1218. 

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measurement. Rhinology 33(3): 138-140. 

44. Yamagiwa M (1990) Evaluation of the effect of localized skin cooling 

on nasal airway volume by acoustic rhinometry. Am Rev Respir 

Dis 141(4 Pt 1): 1050-1054. 

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Suppl 1: S82-84. 

L. Parvez 

Procter & Gamble Health Care Research and 

Development Laboratory 

Thane – Belapur road 

Thane 400601 

India 

Fax : +91-22-769 1597 

Tel : +91-22-769 1807


Acoustic rhinometry and rhinomanometry 

Philip Cole 

The Toronto Upper Airway Studies Group, University Department of Otolaryngology, St Michael’s 

Hospital, Toronto, Canada 

INTRODUCTION 

Currently, rhinomanometry and acoustic rhinometry are the 

objective methods most widely employed for assessment of 

respiratory function and configuration of the nasal airway. A 

review of features of nasal physiology and anatomy that have an 

important bearing on these methods is presented here and is 

followed by comments on relevant laboratory experiences of 

the Toronto Upper Airway Studies Group. 

Kasperbauer and Kern (1987) note that, in many articles and 

discussions, terminology used to describe the nasal lumen, 

especially its proximal segment, can be confusing. They state 

that at least ten different terms are employed of which several 

are synonymous. In the following presentation archaic terminology 

and abbreviation are avoided and descriptive phrasing is 

used as far as it is practical. 

Nasal Physiology and Anatomy 

On nasal inspiration streams of ambient air converge to enter 

the nose via the nostrils. The mainstream funnels through the 

vestibule, squeezes through the narrow valve and becomes 

more widely dispersed as it enters and transits the relatively 

capacious cavum. Convergence of inspiratory airstreams promotes 

an orderly laminar-type flow and cadaver experiments 

indicate that flow through the nasal valve of an adult at rest is 

accelerated to a linear velocity approximating 16 M/s (Swift and 

Proctor, 1977). As the mainstream leaves the narrow valve and 

enters the much larger lumen of the cavum, its linear velocity is 

decelerated by a factor of about 4. Much of the kinetic energy 

(e=kv 2 ) freed by deceleration is dissipated in the generation of 

inertial disturbances of the airstream. These disturbances, produced 

by orifice flow from the valve into the cavum, promote 

both disruption of a marginal lamina of air that would otherwise 

insulate the mainstream from the mucosa and, also of 

importance, mixing in the mainstream. Contact between air and 

mucosa and mixing in the airstream are essential for effective 

conditioning of inspiratory air which involves exchanges of 

water, heat and contaminants. However, this processing is not 

completed in the nose (Cole, 1993) and disturbed (transitional) 

flow (Jaeger and Matthys, 1969) is entrained and sustained by 

ADD airflow velocity (Reynolds) in relatively large cross-section 

air passages to the lungs enabling air conditioning and cleansing 

to con-tinue. In the small pulmonary airways flow is slo- 

wer and less disturbed but the midstream is very close to the 

mucosa and the conditioning process continues. Finally, processed 

inspiratory air mixes with the larger volume of well-conditioned 

residual air before exposure to the alveolar membranes. 

Airflow resistance of the nasal valve results from generation of 

energy in the airstream and, as described above, this energy is 

expended in disturbing the airstream as it leaves the valve and 

enters the cavum. Disturbed flow is essential for effective cleansing 

and conditioning of inspiratory air. In adult subjects breathing 

quietly at rest, the nose provides half the airflow resistance 

of the entire system of respiratory air passages and the short segment 

of the nasal valve furnishes, by far, the greater portion of 

nasal resistance (Hirschberg et al., 1995; Haight and Cole, 1983). 

For the purpose of description the nasal valve can be divided 

into proximal and distal components. As the inspiratory mainstream 

leaves the vestibule it is first constricted and accelerated 

in the narrow lumen of the proximal structural component of the 

nasal valve (Figure 1). This narrowing between the septum and 

the proximal end of the upper alar cartilage is shaped as an acute 

triangle based on the nasal floor and its structure has limited 

flexibility (see below). Distal to the structural component of the 

valve, substantial erectile tissues, supported by the lateral and 

Figure 1. Diagram of the proximal nasal cavity and entrance to the 

cavum.

30 Philip Cole 

Figure 2. Injected nasal specimen demonstrating erectile septal body 

and capacitance vessels. 

(Wustrow F. (1951) Schwellkorper am Septum nasi. Z Anat Entwicklung 

116:139-142). [By permission of Springer-Verlag GmbH & Co. KG] 

septal nasal walls, form the functional component and variable 

blood content of capacitance vessels of the erectile tissues determines 

lumen cross-sectional dimension and consequently, airflow 

resistance of this functional nasal segment (Figures 1-3). 

The inferior turbinate bone is clothed in erectile tissue that 

responds to many local and remote stimuli and to the spontaneous 

nasal cycle (Cole, 1993), by congestion or decongestion. 

Congestion expands inferior turbinate erectile tissue into the 

ventral lumen of the valve and a substantial septal erectile body 

(Wustrow, 1951) situated dorsal to the inferior turbinate and 

proximal to the middle turbinate (Figures 1-3) expands in a similar 

manner into the dorsal valve region. Although substantial, 

this septal tissue is not conspicuous on rhinoscopic examination 

and septal cross-sectional dimensions are obscured by the columella. 

Both septal and lateral erectile tissues extend distally into 

the cavum (Figures 1 and 3) but, by contrast with the valve, the 

cavum is relatively spacious and can accommodate large 

intrusions into its lumen with little effect on resistance to airflow 

(Chaban et al., 1988). 

In healthy subjects at rest, the major source of resistance in the 

respiratory airways is localized to the combined nasal valves. 

Although unilateral valve resistance is continually changing by 

alteration of capacitance vessel tone and blood content, resistance 

of the combined nasal valves is maintained within a narrow 

range by postural and cyclical reciprocation between sides 

(Cole, 1993; O’Flynn, 1993). In healthy noses resistance to respiratory 

airflow is reduced by 1/3 following application of topical 

decongestant and resistance of the decongested nose is reduced 

by 2/3 on wide alar retraction. These interventions minimize 

resistance of both functional and structural components of the 

valve (Cole, 1997) leaving the residual 1/3 of resistance in the 

decongested cavum, mainly in its piriform region (Hirschberg et 

al., 1995). 

The cartilaginous septal wall of the valve is rigid but the upper 

alar cartilage is flexible. It is attached to the lower alar cartilage 

by a fibrous joint and its proximal portion is detached from the 

dorsal septum. Indeed, this valve structure is compliant with 

forceful manipulation such as insertion of a speculum or a nasal 

nozzle, use of a dilator, or displacement of mobile facial tissues 

by a facemask. However, healthy alar tissues resist transmural 

inspiratory airflow pressures (Bernoulli) by their impedance to 

deformation and by inspiratory isometric alar dilator muscle 

contractions (Cole et al., 1985) and by comparison with the 

functional component of the valve, the lumen of the structural 

component is stable. In healthy adults its stability is preserved 

during the increased ventilation of exercise by increased alar 

dilator muscle activity and by decongestion (Richerson and Seebohm, 

1968) which reduces airflow resistance and inspiratory 

transmural pressure. At inspiratory flows of 30 to 35 L/min, 

nasal inspiratory transmural pressure is further reduced by a 

switch to oronasal breathing (Niinimaa et al., 1980). 

It is interesting to note that during spontaneous oronasal breathing, 

at rest or induced by exercise, the labial orifice provides an 

appropriately variable resistor (Cole et al., 1982; Niinimaa, 

1983). Also of interest are the vascular swell bodies that have 

been described in the proximal nasal cavities of rats and rabbits 

during studies of the nasal cycle (Bojsen-Moller and Fahrenkrug, 

1971). These vascular bodies suggest analogy with the 

functional portion of the human nasal valve. The human nasal 

valve, the labial orifice and the animal nasal swell bodies are all 

suitably positioned to disrupt the laminar regime of the converging 

streams of inspiratory airflow and thereby contribute to 

inspiratory air conditioning. 

Dimensions and shape of the airway lumen and airflow velocity 

determine the magnitude of resistance to airflow. Resistance to 

airflow varies inversely and exponentially with lumen cross-sectional 

area and, since lumen dimensions are small in the nasal 

valve region, valve resistance is very sensitive to structural 

and/or vascular mural displacements. 

In both investigatory procedures of rhinomanometry and acoustic 

rhinometry the nasal valve region (the primary airway resistor) 

is a site of major pathophysiological concern. In this critical 

region both rhinomanometric (resistance) and acoustic rhinometric 

measurements (area/distance and volume) are accurate 

and reproducible (Silkoff et al., 1999). 

Acoustic rhinometry 

Acoustic rhinometry has been widely discussed in other contributions 

to this supplement and comments concerned mainly 

with laboratory experience of the Toronto Upper Airway Studies 

Group are made here.

Acoustic rhinometry and rhinomanometry 31 

Acoustic rhinometry provides a minimally invasive, convenient, 

accurate and expeditious method for measuring dimensions of 

the nasal airway and the method has the capability of monitoring 

dimensional changes over short periods of time. Acoustic 

rhinometry is applicable to humans of all ages (Pedersen et al., 

1994; Djupesland and Lyndholm, 1998) and has been used 

experimentally in small animals. We find nasal volume measurements 

to be particularly useful and reliable for assessments 

of mucovascular status and its changes. 

Reported area-distance rhinograph curves from healthy noses 

produced by rhinometers of different manufacture appear similar. 

Indeed, measurements comparing an Eccovision acoustic 

rhinometer (E Benson Hood Laboratories Inc., Pembroke, MA, 

USA) with a Rhin 2100 (RhinoMetrics, Lynge, Denmark) provide 

almost identical results (Djupesland et al., 1999). 

Typically, area-distance rhinographs obtained from healthy 

adult noses demonstrate 2 notches in the proximal 5 cms of 

baseline distance. These notches are generally assumed to correspond 

with locations of the structural component of the valve 

and the “head” of the inferior turbinate (functional component) 

respectively and, when erectile tissue is decongested, the minimum 

cross-sectional area approaches the proximal notch 

(Roithmann et al., 1997a). It is notable that, although locations 

of rhinograph features are <strong>report</strong>ed precisely in mm as baseline 

distances from the nostril, the site in the nostril to which the 

measurements refer is undefined. 

The distance from the dorsal lip of the nostril to the dorsal piriform 

aperture is > 2 cms and the ventral distance is < 1 cm in 

typical adults noses. 

Skilled operators have shown that acceptable reproducibility of 

acoustic rhinometric measurements can be obtained by means 

of a handholding technique. In our own laboratories, we consider 

it prudent (Roth et al., 1996) to stabilize both the subject’s 

head and the sound-tube/adapter (Fisher et al., 1995a) by 

means of an adjustable device (E Benson Hood Laboratories 

Inc., Pembroke, MA, USA). This technique limits measurements 

to the laboratory and is unsuitable for bed-ridden or 

infant subjects but in our laboratories we believe it enhances 

precision and reproducibility for operators of differing skills and 

experience. Together with a strict standard operating procedure 

(Eccles, 1999) stabilization is particularly helpful for the novice 

and for the occasional operator and it enables the experienced 

operator to proceed with added confidence. Measurements 

obtained from decongested noses repeated over time show a 

coefficient of variation < 10% (Silkoff et al., 1999). 

We pay particular attention to the ‘anatomical’ nasal adapter 

and its application. It is chosen from a selection to best fit the 

rim of the subject’s nostril (Fisher et al., 1995b). Precise adjustment 

of the stabilizing device enables the adapter to be applied 

so as to barely touch the rim and thus to avoid the risk of displacement 

of compliant alar tissues. An air seal is completed by 

generous application of a water-soluble gel from a syringe via a 

thin plastic tube. Instability of the resulting area-distance curve 

Figure 3. Demonstration of the medial and lateral nasal walls with the septum hinged forward. The imprint of the septal body is outlined on the lateral 

wall. 

(Wustrow F. (1951) Schwellkorper am Septum nasi. Z Anat Entwicklung 116:139-142). [By permission of Springer-Verlag GmbH & Co. KG]


and/or a readily recognizable abnormal sound suggest an inadequate 

seal which should then be fortified with more gel. If fortification 

is unsuccessful reapplication should be undertaken. 

Current research in Toronto is concerned with respiratory airway 

responses to irritant contaminants of ambient air and 

acoustic rhinometric assessment of nasal volume provides a 

useful measure of nasal mucovascular response. We confine 

volume measurements to the proximal 5 cms of the rhinograph 

baseline distance, which includes the valve lumen and avoids 

more distal sources of error (Hilberg and Pedersen, 1996). Our 

results of volume measurements are reproducible and sensitive 

to mucosal volume change. The high level of accuracy might be 

improved even further (Djupesland, 1998, personal communication) 

by ignoring the proximal 2 cms of the rhinograph baseline 

distance, which does not include erectile tissue, and confining 

volume measurements to the 3 cms immediately distal to it. 

Rhinomanometry 

Nasal airflow resistance is calculated from the ratio between 

nasal airflow and differential pressure measurements from nostril(s) 

to nasopharynx or oropharynx (Rn=PV). Flow is meas- 

. 

ured by a pneumotach and pressure by a manometer. Since the 

inverse relationship between airway lumen and resistance is 

exponential, resulting values provide a highly sensitive indication 

of the effort (work, power) required, or in other words, how 

hard it is, to breathe through the nose. 

Employment of the head-out body plethysmograph (see below) 

provides unhindered access to the nose. It enables alar retraction 

to maximize the lumen of the compliant portion of the 

nose and to minimize its resistance and thus to determine resistance 

of the compliant segment and the residual resistance of 

the cavum, untreated, decongested, bilateral and unilateral 

(Cole, 1997; Cole et al., 1997). 

Nowadays, it is customary for pressure and flow signals to be 

transduced, computed, displayed and recorded electronically. 

Our standard operating procedure includes computation and 

display of the mean and the coefficient of variation of 5 consecutive 

nasal resistance measurements. If the coefficient exceeds 

8%, any aberrant value is deleted and the measurement is 

repeated. We consider 8% adequate for clinical work but smaller 

coefficients can be chosen if greater precision is desired. 

Although general principles of nasal airflow resistance assessments 

are similar, there are differences in techniques of airflow 

and differential pressure measurement. Some we have tested 

and adopted for current use, and other centres have made their 

own choices. 

Airflow measurement 

• Nozzles: Insertion of a nozzle into the nasal vestibule risks 

errors from deformation of the compliant tissues of the nasal 

valve (Fischer et al., 1995b) nevertheless, reliable results 

have been <strong>report</strong>ed (Naito et al., 1991). Lumen of the nozzle 

should be maximized to minimize added resistance. 

• Face masks: Pressure against the face, to ensure an adequate 

seal, also risks interference with the valve lumen by displacement 

of the upper lip and/or other mobile facial tissues, even 

as far from the nostrils as the zygomatic region. In our early 

work be used SCUBA masks and later recognized they were 

particularly bad in this regard. Aviator and fireman masks are 

less invasive but choice of size is limited. CPAP masks are 

comfortable and convenient and, if applied with care, can 

yield reproducible results. 

• Head-out body plethysmograph (displacement type): This 

bulky but simple and reliable apparatus (Cole et al., 1997) has 

many advantages and is used in several centres throughout 

the world. The risks associated with nozzle and mask techniques 

are avoided. The face, nostrils and alae are available for 

unimpeded study or manipulation (eg alar retraction). The 

equipment does not require sterilization between subject 

assessments. The dimensions are suitable for subjects of all 

sizes and the subjects, especially children, prefer plethysmography 

to facial masking. More than 2000 patients are assessed 

annually in Toronto by this method. 

Differential pressure measurement 

• Between oropharynx and nostril: (Posterior rhinomanometry) 

With lips closed about an oral tube the subject is encouraged 

to maintain patency of the oropharyngeal aperture 

during exclusive nasal breathing. Patience, persuasion and 

encouragement are essential and feedback from a monitor 

screen is helpful. In the hands of an experienced operator, 

despite statements to the contrary, failure is rare, even with 

children as young as 4-5 years. We use this method successfully 

for about 500 children annually in order to detect and 

assess both nasal and adenoid airway obstructions. 

• In a sealed nasal vestibule: (Anterior rhinomanometry) As 

the subject breathes through the opposite side, nasopharyngeal 

pressure is transmitted to the sealed vestibule and can 

be measured via a small plastic tube. This technique is less 

demanding of patient cooperation than the preceding one 

and is widely used, but repeated reapplications of the mask 

and the vestibular seal required for a thorough examination 

are time consuming and risk introduction of errors. Adenoid 

airway obstruction cannot be assessed by this method. 

• Between nostril and nasopharynx: A fine plastic tube (Infant 

Feeding Tube 8F) is passed 8 cms along the floor of the adult 

nose and secured to the upper lip with adhesive tape. If it is 

passed without hesitation and contacts only the nasal floor, 

the subject is not disturbed (Cole et al., 1997). The proportion 

of respiratory airflow along the nasal floor is small (Swift 

and Proctor, 1977) and the tube does not add significantly to 

nasal airflow resistance. The method requires minimal subject 

cooperation and is in general use for our adult patients. 

Adenoid airway obstruction cannot be assessed by this 

method. 

Differential transnasal pressure values used in calculation of 

nasal airflow resistance (Rn=P/V) also differ between centres. 

Five common examples are: 150 Pa, 100 Pa, 75 Pa, at peak and 

by digital averaging. In adult subjects breathing at rest through

Acoustic rhinometry and rhinomanometry 33 

combined nasal cavities, resistance values derived from 75 Pa, 

peak and averaging methods correspond closely in the resistance 

range < 0.4 Pa/cm 3 /s (Naito et al., 1989). Fortunately, this 

range includes the upper resistance limit of 0.25 Pa/cm 3 /s for 

unobstructed noses so all three methods provide similar values 

for resistances over a clinically useful range. At resistances > 0.4 

Pa/cm 3 /s the values diverge. 

In our experience of adult noses of caucasian, oriental or negroid 

subjects breathing quietly at rest through combined unobstructed 

nasal cavities, only a minority achieve a differential 

pressure as great as 100 Pa (Ohki and Hasegawa, 1986; Ohki et 

al., 1991) and since an increase in differential pressure requires 

hyperventilation 75 Pa is preferable for resting values. 

Choice of Method 

Rhinomanometry has been in clinical (> 2000 patients/year) 

and research use in our Toronto laboratories for several years. 

Clinical plethysmograph rhinomanometric tests receive provincial 

health insurance fees for service but these fees are not available 

for acoustic rhinometry and its use has been confined 

mainly to research. 

In each method of measurement the resistive and dimensional 

consequences of continual changes of nasal mucovascular 

status that take place over time must recognized (Corey et al., 

1997). Topical decongestant can be employed when it is necessary 

to measure or abolish these confounding factors which are 

associated with the functional component of the valve. 

Rhinomanometry is a dynamic test of resistance to nasal airflow. 

It is very sensitive and provides a simple numerical value 

that indicates how hard it is to breathe through the nose. During 

resting breathing, resistance of the combined cavities of the untreated 

adult nose > 0.25 Pa/cm 3 /s indicates obstruction. 

Decongestion and alar retraction of the separate nasal cavities 

enable the sites and magnitudes of mucovascular and structural 

components of resistances of each nasal cavity to be determined 

(Cole, 1997), in children adenoid resistance to airflow is measured 

also. A complete test occupies > 20 mins. 

Acoustic rhinometry is a static test of nasal lumen dimensions; 

it is independent from airflow, less invasive and more expeditious 

than rhinomanometry but evaluation of obstruction to 

nasal breathing is less simple. eg “A minimum cross-sectional 

area equal to 0.50 cm 2 , a cross-sectional area at the piriform 

aperture of 0.70 cm 2 and a large effect of decongestion on the 

minimum cross-sectional area were found to be the best variables 

to separate obstructed from normal noses” (Grymer et al., 

1997). Adenoid obstruction cannot be measured by this 

method. 

In both methods, as described above, the valve region is the 

primary region of pathophysiological interest. 

The usefulness of results depends on the sensitivity, specificity 

and reproducibility of the method employed and although 

numerical representation of all these features is not yet available 

illustrative examples can be given. 

Sensitivity 

• Both methods are sensitive to cross-sectional dimensions of 

the nasal lumen and their hanges(Roithmann et al., 1994; 

Roithmann et al., 1997a; Szucs and Clement, 1998; Porter et 

al., 1996). 

• Rhinomanometry is particularly sensitive since resistance to 

airflow resistance bears an exponential relationship with 

lumen cross-sectional areas. 

Specificity 

• Both methods provide results with a close relationship to 

imaging studies (Corey et al., 1997; Gilain et al., 1997; Cole 

et al., 1989). 

• Results of neither rhinomanometry nor acoustic rhinometry 

provide a significant correlation with the sensation of nasal 

patency of subjects breathing through the combined nasal 

cavities but in both methods unilateral measurements are 

significantly correlated with ipsilateral sensation (Kim et al., 

1998; Roithmann et al.,1994; Kesavanathan et al., 1996). 

Reproducibility 

• Measurements by both methods repeated over time show a 

reproducibility well within the range of many widely accepted 

clinical tests (Silkoff et al., 1999). 

The two methods have been compared in allergy challenge studies 

and acoustic rhinometry has been found as the more 

convenient and also more expeditious in capturing transient 

mucovascular changes following minimal challenge doses 

(Roithmann et al., 1997b). It is also the method of choice for 

studies of infants and bed-ridden patients (Djupesland and 

Lyndholm, 1998). In cases of nasal obstruction demonstrated 

initially by rhinomanometry, surgeons have commented favourably 

on the value that additional acoustic measurements provide 

in planning and performing septo-rhinoplastic and revision 

procedures (Roithmann et al., 1997a).Currently we are using 

acoustic rhinometry for convenience in nasal volume measurement 

during the investigation of environmental exposures and 

we continue to use the more sensitive rhinomanometric 

method for clinical diagnostic purposes. 

CONCLUSIONS 

Acoustic rhinometric and rhinomanometric methods are well 

established for quantitative assessments of nasal airway respiratory 

function and configuration. Sensitivity, specificity and 

reproducibility of results obtained by both methods are well 

within the range of results obtained by other generally accepted 

laboratory procedures. Each method has uniquely useful properties, 

neither is a substitute for the other and the two methods 

can be complementary. 

Results obtained by the two methods from widely differing 

noses are mutually consistent but statistical examination has 

not revealed any simple mathematical relationships between 

them. 

As Eccles (1999) has emphasized, a well-designed Standard 

Operating Procedure is essential for achievement of worthwhile 

results, by either acoustic rhinometry or rhinomanometry.


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Philip Cole MD FRCSC 

65 Spring Garden Avenue #101 

Toronto 

Ontario 

CANADA M2N 6H9 

Phone: +1-416-733-8220 

Fax : +1-416-229-6278 

E-mail: philip.cole@utoronto.com

CASE REPORT 


Clinical applications of acoustic rhinometry 

Luisa F. Grymer 

ENT-department, University Hospital, Aarhus, Denmark 

SUMMARY 

The clinical value of acoustic rhinometry (AR) is its ability to measure the dimensions of the 

nasal cavity in terms of a curve describing the cross-sectional areas as a function of distance. 

This curve describes nasal airway patency and gives an impression of the degree of nasal 

obstruction. The method provides values before and after decongestion which allow to evaluate 

the cause of the nasal obstruction as mainly skeletal or mucosal. This makes AR a tool for 

diagnosis and follow-up of treatment in both rhinology and rhinosurgery. Similarly, AR is a 

reliable method to show the dimensional changes of the nasal cavity before and after a given 

treatment. In the evaluation of a surgical intervention it is reasonable to use deconge sted values. 

Turbinate surgery, septo- and rhinoplasty, orthognatic surgery and paranasal sinus surgery 

and their influence on the dimensions of the nasal cavity may be reflected by AR. The 

absolute minimum cross-sectional area, and cross-sectional areas and volumes at fixed distances 

are the recommended parameters to show dimensional changes after nasal surgery. The 

predictive value of AR, in relation to nasal obstruction, should have high specificity and sensitivity 

to be used in a clinical setting. It seems that the single variables do not provide enough 

information for the diagnosis of obstruction, and it has been stressed that the results should 

be interpreted together with rhinoscopy and subjective complaints. A statistical model based 

on questionnaire, rhinoscopic findings and several variables from AR has been proposed to 

increase the diagnostic specificity and sensitivity of AR. 

Key words: acoustic rhinometry, selfassesment, rhinosurgery 

INTRODUCTION 

The indications for nasal surgery are often based on the experience 

of the surgeon, on a trial and error basis. Although the 

right diagnosis is the cornerstone of sucess, objective assess 

ment of nasal patency is not common practice among experienced 

rhinologists or rhinosurgeons. However, in addition to evaluation 

of the feeling of nasal obstruction it may be of advantage 

to apply reliable objective methods. They are necessary also 

for evaluation of the outcome of surgery on the outer or inner 

nose in addition to the patient´s feeling of nasal patency. Furthermore, 

insurance companies and health authorities will, in 

the near future for legal reasons, force the doctors to objectivize 

the indications and the results of nasal interventions. 

Acoustic rhinometry (AR) was introduced by Hilberg et al. for 

the first time with clinical diagnostic purpose in the ENTdepartment 

of the University Hospital in Aarhus (Denmark) in 

1987 and the first publication about the clinical application 

(Grymer et al.) of AR appeared in 1989. Thirteen years later, at 

the turn of the century, about 200 papers on different aspects of 

AR have been published and one third are dealing with AR and 

surgery. The clinical value of AR is its ability to measure the 

dimensions of the nasal cavity in terms of a curve describing the 

cross-sectional areas as a function of distance. This curve describes 

nasal airway patency and gives an impression of the degree 

of nasal obstruction. The method provides values before 

and after decongestion which allow to evaluate the cause of the 

nasal obstruction as mainly skeletal or mucosal. This makes AR 

a tool for diagnosis and follow-up of treatment in both rhinology 

and rhinosurgery. Similarly, AR is a reliable method to show 

the dimensional changes of the nasal cavity before and after a 

given treatment. However, the question of whether AR add any 

further information to the case history of obstruction and to 

anterior rhinoscopy and how well it correlates with the subjective 

feeling of impaired nasal patency are still a matter of debate, 

(Grymer et al., 1998). Also, the uncertainty about AR as a diagnostic 

tool may lead to inappropriate application (Tomkinson, 

1997). The purpose of this paper is to give a critical analysis of 

the literature on the clinical, medical and surgical, applications

36 Grymer et al. 

of AR and to give the author´s experience in this field based on 

casuistic examples. 

Figure 1. AR-curve of a patient with mainly left-side nasal obstruction. 

On rhinoscopy a deviation anteriorly to both right and left side was present. 

On the left side the MCA

Clinical applications of acoustic rhinometry 37 

Figure 2a. Case no.1. AR-curve showing the effect of operation on the 

decongested nasal cavity. A significant improvement is seen in both 

sides. The postoperative values do not reach normal values. VAS= visual 

analogue scale expressing the feeling of nasal patency. 0 =completely 

open and 5 = completely closed. 

gesting skeletal obstruction. The indication for septoplasty was 

clear. Open septorhinoplasty with lateral and transversal osteotomies 

was done to improve the apperance of the external nose 

and make the septum straight (Figure 2b). After operation and 

in decongested state the MCA moved slightly anteriorly on the 

right side (from 2.33 to 1.97 cm) and it was unchanged located 

1.97 cm on the left side. 

The most important information from AR is that septorhinoplasty 

resulted in an increase of the right MCA by 93% and of 

the left MCA by 47% compared to the preoperative values. The 

patient was also completely happy about the apperance and the 

nasal patency, although the postoperative values were much 

below normal values. This indicates either the influence of the 

rhinoplasty procedure or the limitations of the septoplasty, or 

the result of developmen tal decreased growth of the nasal cavity. 

The subjective feeling of patency was expressed on a visual analogue 

scale (VAS), where 0 was completely open and 5 completely 

closed, inmediately before AR measurement . On the right 

Figure 2b. Case no.1, croocked and obstructed nose preoperative (above) 

and after open septorhinoplasty (below). 

side VAS = 3 and on the left side VAS = 1. After operation she 

felt completely open airways on both sides (VAS = 0). 

Is this a good or bad correlation of selfassesment to AR ? Often 

the patients have difficulties to express nasal patency, specially 

if it fluctuates. In this case, she probably compared the patency 

before operation with how impaired it could be during a cold, 

when she felt obstruction as a problem. Otherwise she should 

have had VAS 5 since the MCA was 0.02 cm 2 . In this case there 

is no doubt of the indication for septoplasty (based on rhinoscopy 

and AR), though the patient was not as disturbed by the 

nasal obstruction as for the apperance of the nose. 

Case no. 2 

A 30 years old man, earlier boxer, had several nasal trauma. 

Main complaint was bilateral nasal obstruction most by the left 

side. On anterior rhinoscopy a moderate septal deviation was 

found on both sides. There were no symptoms of allergic or 

infectious rhinitis. The preoperative VAS showed that the left 

side was more closed than the right and his feeling of obstruction 

was not severe. It corresponded well with (Figure 3) the AR 

curve, the left MCA was 0.23 cm 2 , smaller than right MCA of 

0.56 cm 2 . The effect of decongestion at MCA was normal (20% 

and 25%, right/left). A septoplasty and bilateral turbinoplasty


Figure 3. Case no.2. AR-curve of the preoperative values on the left side, that together with the rhinoscopic finding indicated clearly to do a septoplasty. 

Decongested values are used to show the effect of operation. It shows a subtle increase of the MCA and a value on the left side below normal. Reduction 

of the inferior turbinate done on the right side achieved an even greater effect on the skeletal space. Insatisfaction with operation may be due to the 

differences between left and right side. 

were performed. Turbinate surgery was done because the author 

anticipated that the narrow MCA could not be increased by 

correction of the moderate septal deformity alone. One year 

later he was not satisfied and complained of obstruction of the 

left side like before operation. The decongested MCA showed a 

subtle increase 24% / 28%, right/ left, of the preoperative values 

on both sides. 

The septum was straight and there was no ala insufficiency. On 

the postoperative decongested AR the MCA on the left side is 

still smaller (0.43 cm 2 ) than on the right side (0,92 cm 2 ). The 

patient´s feeling of obstruction was probably due to the difference 

between right and left side. Since the septum was straight 

after operation, the turbinates were reduced and the MCA 

dimensions were better (but far from normal) no indication for 

further operation was found. Probably a reduction of the turbinate 

on the right side should not have be done. 

Several studies of normal values from AR on caucasian noses 

(Lenders and Pirsig, 1990; Grymer et al., 1991; Cole et al., 1997; 

Maerker et al., 1998; Corey et al., 1998) show similar results but 

there are wide ranges for the MCA. This may be confusing in 

the single individual like in this case. We should think of the 

critical values for AR in relation to nasal obstruction (Grymer et 

al., 1997). The factors influencing the feeling of nasal patency on 

the two sides may include the size of the MCA on the given side 

as well as the difference between the two sides. Another source 

of variation may be the resting ventilation and the subjects level 

of activity. Small sedentory subjects would be expected to feel 

less obstruction for a given cross-sectional area than large active 

subjects like this boxer. 

Case no. 3 

A 26 years old man without known nasal trauma. His main 

complaint was bilateral nasal obstruction, especially disturbing 

at bed time in recumbent position. Based on history and rhinoscopy 

one rhinosurgeon found indication for septoplasty. On 

anterior rhinoscopy there was a small to moderate septal deviation 

to the left. He had pronounced feeling of nasal obstruction 

before decongestion on both sides (VAS= 4) and good effect of 

decongestion (VAS 0/1, above / below). AR shows (Figure 4) 

MCA before decongestion very small bilaterally (0.35/ 0.29 cm 2 , 

above/ below). The effect of decongestion is large at the MCA


Figure 4. Case no.3. AR-curve before and after decongestion, showing 

almost 100% increase in MCA with decongestion. The MCA moves 

anteriorly after decongestion. 

Figure 5a. Case no.4. Before (above) and after (belowe) reduction rhinoplasty 

(humpremoval and tipplasty). 

41% / 47%, above / belowe. In both sides the MCA move anteriorly 

after decongestion especially on the right side. Because he 

had symptoms of vasomotoric rhinitis and a pronounced mucosal 

factor, he got local steroids during 2 months, which gave a 

satisfactory feeling of nasal patency and no operation was done. 

In this case I will not consider to do a septoplasty because of the 

rhinoscopy findings (slight deviation). I would instead consider 

doing a reduction of the anterior part of the inferior turbinate 

with reduction of the mucosa and the bony skeleton, but only if 

he had subjective feeling of nasal obstruction after the local steroids. 

We found (Grymer et al., 1997) that an effect of decongestion at 

the MCA of more than 0.20 cm 2 is of predictive value for nasal 

obstruction. In case of nasal obstruction and subtle or none septal 

deviation the surgical eye turns to the inferior turbinates. 

However, the question of how to find the right candidates for 

turbinate reduction, based on objective terms, has not been 

answered yet. 

In the most extensive study published recently (Passali et al., 

1999) different types of turbinate sugery were performed in 382 

patients. The selection was based on the effect of decongestion 

on nasal resistance but also AR had been done, although not 

Figure 5b. AR-curve of case no.4 . Decongested values are used to compare 

the effect of operation on the skeletal frame. The anterior part of 

the nose decreased very much when comparing the dimensions before 

and 5 years after reduction rhinoplasty. VAS = visual analogue scale 

shows no change on the feeling of nasal obstruction.


Figure 6a. Case no.5. Chronic mouthbreather, with long face apperance, 

lips appert position and mouth breathing. 

Figure 6b. Acoustic Rhinometry curve of case no.5. showing small nasal 

cavity, specially at the pyriforme aperture (distance = 2.3/2.6), with very 

little effect of decongestion and no septal deviations seen on rhinoscopy. 

used for the selection. No attempt was done to show how many 

actually had turbinate hypertrophy. The wide range of patient’s 

age from 8 years to 70 years of age makes the mean values of the 

volumes less usefull. Lenders and Pirsig (1990b) introduced the 

term of the C-notch as the deflection on the AR curve corresponding 

to the inferior turbinate, and it may be the same as the 

CSA2 of other authors like Kenker et al. (1999). Nevertheless, 

they did not described what turbinate hypertrophy is. Grymer et 

al., (1996), suggested a definition of mucosal turbinate hypertrophy 

if there is a 100% increase in cross-sectional area of either 

the MCA or the CA-3.3 (at the pyriforme aperture) following 

decongestion. Nevertheless, the nasal cycle may influence this 

increase. To avoid this it could be suggested to apply total values 

(sum of both nasal cavities), but this will only be correct for 

individuals with true cycles, and this seems only to be in 30% of 

the population. 

AR in rhinoplasty, maxillofacial surgery and congenital facial malformations 

The purpose of rhinoplasty is usually to change the apperance 

of the outer nose either for cosmetic reasons or as part of a functional 

procedure. Then it is often combined with sep toplasty or 

turbinate surgery. AR applied to rhinoplasty should have the 

purpose to monitor the result of the operation, to give guidelines 

for the right operation, and to warn about possible problems 

(Constantian and Clardy, 1996; Grymer, 1995; Wustrow and 

Kastenbauer, 1995). However, most studies on aesthetic rhinoplasty 

are not concerned with nasal function and objective test 

are seldom performed. The combination of several surgical procedures 

may jeopardize the results too. 

Case no. 4 

A 45 years old man without any problems with nasal patency. 

He wanted a smaller nose. Conservative humpremoval and tipplasty 

were performed. On rhinoscopy no septal deviation was 

present. Five years later he had no functional problem but he 

would have wanted that the rhinoplasty had achieved an even 

smaller nose (Figure 5a), although he was satisfied by and large. 

VAS before and after operation was 0, (completely open) when 

bilaterally decongested. AR before operation shows a supernormal 

(big) nose (Figure 5b) with MCA decongested of 1.02 

cm 2 /1.13cm 2 on above/below. The MCA postoperatively had 

decreased to 0.36 cm 2 /0.35cm 2 . 

In this case as it has been pointed before it is surprising that 

despite the decrease of MCA to under critical values the VAS is 

unchanged normal.This again raises the question of what VAS 

expresses. In relation to aesthetic rhinoplasty it has been known 

that reduction rhinoplasty may result in impaired nasal patency 

in certain individuals , mostly due to lateral osteotomies (Grymer, 

1998; Webster et al., 1977; Grymer et al., 1999). AR is an 

ideal method to show the changes of the nasal dimensions 

following rhinoplasty. The decongested values of the MCA and 

of the total MCA are recomended before and after operation


(Gosepath et al., 1997; Roithmann et al., 1997). Also total volume 

and probably other decongested parameters for specific 

parts of the nose will be appropriate to study. 

Probably the osteotomies result in a decrease of the internal 

dimensions of the nasal cavity. Therefore it is not resonable to 

combine septoplasty and septorhinoplasty procedures in studies 

of the effects of either procedure, which was also demonstrated 

for case no. 1.Congenital nasofacial malformations like choanal 

atresia may be diagnosed by acoustic rhinometry (Djupesland et 

al., 1997), but rhinoendoscopy will be necessary to support the 

diagnosis. 

Cleft palate patients present very often nasal deformities that 

are a challenge to the rhinosurgeon because its complexity and 

the not always good results. AR may be specially helpfull to 

study the characteristics of these types of noses (Kunkel et al., 

1999). Whether the study of the anterior, the middle and posterior 

segment of the nose is relevant or not in these very 

obstructed noses may be discussed because of the uncertainties 

of AR determinations, areas and volumes behind a very narrow 

segment. 

Maxillofacial surgery of the middle face includes very often the 

nose and the respiration mode may influence the long-term 

postoperative results.The impact of the operation on the nose 

seems to be another ideal field for AR since it is the skeletal 

frame (decongested) of the nose we want to evaluate. The 

results will probably depend on whether different types of interven 

tions are made together (i.e. turbinate surgery, osteomies, 

etc) (Kunkel and Hochban, 1997). 

Case no. 5 

An 18 years old man referred for orthognatic maxillo-mandibular 

surgery due to teeth malocclusion (Figure 6a). He has always 

been mouth breather. He can breathe through the nose but he 

feels it as a heavy respiratory effort. We examined the possibility 

to improve nose breathing. Anterior rhinoscopy showed no 

septal deformity but the impression of a narrow nasal cavity. AR 

shows (Figure 6b) small Total MCA = 0.6 cm 2 / 0.4 cm 2 , right / 

left decongested and very little degree of congestion. The 

decongested total volume from nostrils to 7 cm posteriorly was 

14.5 cm 3 which is much below normal values (Grymer et al., 

1991). 

Due to the small total MCA, I considered a reduction of the 

inferior turbinates, but in a chronic mouth breather with a small 

total volume of the nasal cavity, turbinate reduction will most 

probably not change the mode of breathing. Therefore no nose 

operation was done. To my knowlegde there are no relevant 

studies on this subject. It could be relevant in cases like this to 

evaluate the rhinopharynx dimension. However, several studies 

(Elbrønd et al., 1991; Hilberg et al., 1996; Kunkel et al., 1998; 

Rhiechelmann et al., 1999) seem to indicate AR, in its actual 

state, as unreliable to evaluate the rhinopharynx. 

AR in paranasal sinus problems 

Nasal obstruction and diminished sense of smell are main 

symptoms associated with chronic rhinosinusitis, irrespective of 

whether it is treated surgically by FESS (Lund and Scadding, 

1994; Rowe-Jones and Mackay, 1997; Hummel et al., 1998) or 

medically (Elbrønd et al., 1991a; Mygind et al., 1997; Graf and 

Hallen, 1998). AR seems to be usefull to link the effect of the 

treatment of obstruction and olfaction. For the feeling of patency 

either cross-sectional areas or volumes have been applied. 

Volumes seems to be best linked to olfaction. It seems that the 

volume is the preferred parameter. However, it has not been 

studied if the volume at the middel third of the nasal cavity is 

the most specific dimension in cases where olfaction is impaired 

and congestion pronounced. 

AR in snorers and sleep apnea patients 

There has been an increasing interest in the evaluation of the 

nasal cavity in snorers and patients with sleep related breathing 

disorders (SRBD) as many of these patients have impaired nasal 

patency (Maerker et al., 1994). The MCA and other areas of the 

anterior part of the nose as well as the volume of the nasal cavity 

have been applied to describe the snorer´s nose. Interesting 

studies of the possible effect of obstruction of the naso-oropharynx 

on the nose have shown that congestion of the mucosa of 

the anterior part of the nose decreased in snorers (Antila et al., 

1997) after treatment by Laser UPPP and in children after adeno-tonsillectomy 

(Kim et al., 1998). 

DISCUSSION 

Data from acoustic rhinometry, when used correctly, may give 

valuable information about skeletal changes of the nose following 

rhinosurgery of different types and following local or systemic 

medical treatment of the nose. To get reliable data is necessary 

to fulfill certain standard procedures. Important is probably 

that each laboratory/country has its own reference material, 

extensive enough in number, and a trained staff working under 

suitable conditions. 

When it comes to the value in the diagnosis of nasal obstruction 

the data from literature are not always convincing. One study 

concluded that AR cannot be used for any purpose in the dignosis 

and control of rhinosurgical patients (Reber et al., 1998), 

but, like in other studies a combination of different procedures 

(septoplasty, rhinoplasty, UPPP, turbinoplasty) are being evaluated 

together. If we want realiable answers we have to ask (and 

do) the right things. 

The feeling of nasal patency is an individual and complex 

parameter, which influences the decision about the preferred 

treatment. More research about the meaning of the Visual Analogue 

Scale in relation to different objective methods is needed. 

It is not known, in the single individual, which change in the 

internal dimension of the nasal cavity is necessary to change 

(increase or decrease) the feeling of nasal patency. Neither it is 

known if this change is different between subjects. Case no. 4 

showed that the range of MCA in the same person may be very 

wide, without the person being aware of it. In other subjects 

(case no. 2) the range may be very narrow. 

The predictive value of AR, in relation to nasal obstruction, 

should have high specificity and sensitivity to be of use in a 

clinical setting. The single variables alone do not provide


enough information for the diagnosis of obstruction, as shown 

by Grymer et al. (1997). Several authors like Fisher (1997) and 

Tomkinson (1997) have stressed that the results should be interpreted 

together with rhinoscopy, subjective complaints and 

other diagnostic procedures, because the obstruction may be 

due to tumor, foreign bodies, crusts, septal deviations etc. The 

Aarhus group (Grymer et al., 1997, 1998) constructed a statistical 

model in which questionnaire answers, rhinoscopic 

findings and several variables from AR were included and this 

resulted in much better specificity and sensitivity. Nevertheless, 

the model has not been validated in a clinical diagnostic setting. 

The role of rhinomanometry as a complementary diagnostic 

tool has to be stablished. Rhinomanometry is a dynamic test 

and as such may be more liked to reflect dynamic phenomena 

like feeling of obstruction. 

Several efforts have been made to define the different notches 

in the AR-curve. I think it is more important to find a model 

with high specificity and sensitivity to define variables that are 

comparable between pre- and posttreatment. The variables 

from AR used in different laboratories are related to the software 

available in the rhinometer of the center. 

There are groups (Kemker et al., 1999) calculating the areas of 

and the distances to the first 3 minima on the AR-curve, 

(CSA1,CSA2, CSA3), corresponding to the anterior, middle 

and posterior third segment of the nose. The software of another 

system gives the possibility to calculate automatically the 

MCA in the first 2 cm of the nose and the MCA from 2-4 cm in 

the nasal cavity (Antila et al., 1997). We work with a software 

that calculate the narrowest minimum cross-sectional area of 

the whole nasal cavity (MCA) and the distance from the end of 

the nosepiece. Also 2 cross-sectional areas at fixed points (crosssectional 

areas at 3.3 and 4.0 cm distance from the end of the 

nosepiece) are calculated. In any nasal cavity there is only one 

MCA at the time and at a certain distance. Although the minima 

may be of importance for the feeling of nasal obstrcution, 

they are of less importance for monitoring nasal cavity dimensions. 

This is because the distance to the minima as well as the 

size of the minima may change with the intervention (medical 

or surgical). For that reason I find changes in areas at fixed distances 

to be much better to reflect dimensional changes. The 

absolute minimum, however, is still an important parameter. 

CONCLUSION 

Acoustic rhinometry gives valuable information about skeletal 

changes following rhinosurgery. Decongested values of the 

MCA and of other cross-sectional areas at fixed distance are 

recommended. In relation to diagnosis of nasal obstruction and 

to follow the medical treatment of different rhinological diseases 

both cross-sectional areas and volumes may be recommended. 

Nevertheless, the single variables do not provide 

enough information for the diagnosis of nasal obstruction. 

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Luisa F. Grymer 

ENT-department 

University Hospital 


Denmark


Nasal histamine challenge: a reproducible model 

of induced congestion measured by acoustic 

rhinometry 

L. Parvez 1 , O. Hilberg 2 , M. Vaidya 1 , A. Noronha 1 

1 

2 

Procter & Gamble Health Care Research and Development Laboratory, Thane, India. 

Institute of Environmental & Occupational Medicine, University of Aarhus, Aarhus, Denmark. 

SUMMARY 

We describe the development of a clinical model of nasal congestion using a fixed dose histamine 

challenge in normals. The objective was to use histamine to induce a similar degree of 

nasal congestion as a natural common cold (from unpublished data of 250 cold sufferers) and 

thus establish a rapid screening system for decongestant drug effects. Sixtynine normal subjects 

were challenged with histamine diphosphate (300µg/nostril) on 2 visits. Thirtytwo subjects 

were identified showing reproducible baseline values (< 15%CV (coefficient of variation)) 

and adequate nasal congestion (minimum 20%) without excessive sneezing. Reproducibility 

was evaluated in them post challenge using acoustic rhinometry and rhinomanometry. Twentythree 

subjects showed a variation < 25%CV of nasal volume over multiple visits in a 5 month 

period. The average reduction in nasal volume and airflow 15 minutes post challenge was 32% 

and 41% respectively. Acoustic rhinometry values were less variable than rhinomanometry values. 

Negligible differences (< 2%) in histamine response over visits and similar correlation 

between measured values at first, second and last visits indicate that 2 visits are adequate to 

evaluate response reproducibility in a selected population. We conclude that it is feasible to 

develop a robust clinical model of nasal congestion using histamine. 

Key Words: histamine challenge, reproducibility, acoustic rhinometry 

INTRODUCTION 

As a first step towards developing a clinical model of nasal congestion 

that would serve as a rapid screening system for decongestant 

drug effects, we examined response reproducibility for a 

fixed dose of intranasally administered histamine in normal 

subjects. The method was designed to induce a similar degree 

of congestion as a natural common cold and was based on baseline 

data of 250 natural colds sufferers (gathered from previous 

controlled clinical trials conducted in our laboratory). 

Histamine congested subjects have been used to assess the 

effect of antihistamines, anti-allergy drugs, decongestants in 

patients with seasonal or perennial allergic rhinitis (Hilberg et 

al., 1995; Bousquet et al., 1988; Corrado et al., 1987; Britton et 

al., 1978) using the endpoint titration method and threshold test 

with increasing histamine doses. However, only a few studies 

have examined reproducibility of response to histamine in allergic 

rhinitics (Van Wijk et al., 1988; Corrado et al., 1987) and normals 

(Austin and Foreman, 1994; Gronborg et al., 1986) and 

none to a single histamine dose as investigated in this study. 

The nasal congestion response was objectively quantified using 

well standardized nasal patency measurement techniques of 

acoustic rhinometry (Parvez et al., 2000) and active anterior rhinomanometry. 

With the exception of Hilberg et al. (1995) and 

Austin and Foreman (1994), nasal occlusion during histamine 

challenge has been measured mostly by nasal airway resistance 

using rhinomanometry. However, for various reasons we decided 

to use acoustic rhinometry supplemented with rhinomanometry 

to allow comparison with published literature. 

MATERIALS & METHODS 

Subjects 

Sixtynine healthy volunteers who were non smokers, 17 male 

and 52 female, mean age 27 years (range 18-45), entered the 

study after medical screening during the period May - September 

1997. They had no history of recent common cold (within 

the last month), atopic disease, perennial rhinitis or chronic 

symptoms from the airways. None were on chronic medication 

and no drugs were allowed 48 hours prior to entry on a study 

day. Subjects were excluded if they had structural nasal abnor-


mality during ENT examination such as septal deviation, turbinate 

hypertrophy, and polyps. Informed consent was obtained 

prior to subject participation. 

Challenge agent 

Histamine diphosphate (histamine), MW 307, purity 99%, 

(BDH, Poole, UK), at a single concentration 0.3% w/v, was formulated 

without preservatives and sterilized by filtering 

through a 0.2µm cellulose nitrate membrane prior to filling 

aseptically into 15mL metered dose spray bottles. The bottles 

were fit with the VP7 pump type spray head (Valois) dosing 

50µL per actuation (dosing accuracy 90%). Storage temperature 

was between 8-15 0 C and fresh samples were made every 15 

days. All supplies were qualified by chemical analysis for histamine 

content using a validated high performance thin layer 

chromatography method. 

Table 1. Primary screening criteria for medically suitable subjects. 

Inclusion Criteria 

1 Subjects compliant, available for repeated visits. 

2 Stable baseline (pre-challenge) values, less than 15% variation 

between visits. 

3 Congestion response to histamine challenge greater than 20% change 

from baseline. 

4 Sneezing that is not excessive (immediate response less than 5 sneezes). 

5 Minimum nasal cross sectional area greater than 0.15 sq.cm. 

Nasal challenge 

Subjects were seated upright with head position stabilized 

against a headrest. The nozzle of a metered dose spray pump 

was gently introduced into the nasal vestibule and aligned 

approximately in the nasal axis by trained technicians. Subjects 

were asked to briefly stop breathing, and two sprays were discharged 

in rapid succession in each nostril, thus delivering 

300µg of histamine diphosphate in a 100µL volume per nostril. 

Pre and post dosing weights from the spray bottle were recorded 

to ensure accurate dosing. 

The histamine dose of 300µg per nostril was determined from a 

previous dose response evaluation in a randomly selected population 

of 30 normal subjects. The 300µg dose produced levels 

of nasal obstruction comparable to that in natural common 

colds measured by nasal airway volume from acoustic rhinometry 

and airflow by rhinomanometry (Figure 1). 

Measurement methods 

Acoustic Rhinometry measurements were made by well trained 

and qualified operators using the SRE 2000PC continous wide 

band acoustic rhinometer (Rhinometrics, Denmark) attached to 

the nose with contoured noseadapters (Figure 2). Measurements 

were made in a highly controlled and standardized way 

as described separately (Parvez et al., 2000), using well calibrated 

and qualified equipment. Thus, nasal area distance curves 

were obtained which describe the cross-sectional area of the 

nasal passage as a function of distance inside the nose (Hilberg 

et al., 1989). From the nasal area distance function the nasal airway 

volume in the anterior segment (10-64 mm), which includes 

structures like the nasal valve and turbinates was calculated. 

Active anterior rhinomanometry using the GM NR62 rhinomanometer 

(GM Instruments, UK) and nozzles (contoured 

nose adapters), was executed with the same control and standardization 

as acoustic rhinometry (Figure 2). Once again trained 

operators and well qualified equipment were used. According 

to recommendations of the International Standardization 

Committee (Clement, 1984), the pressure flow relationship (rhinometry 

curve) during quiet breathing cycles was recorded and 

nasal airflow values at 100 Pa used as the primary variable. 

Study design 

A primary selection process was employed and all 69 medically 

screened, normal subjects were evaluated for compliance to certain 

minimum criteria (Table 1). These criteria were tested over 

2 visits approximately a week apart. The process helped identify 

a group of subjects that were likely to comply and participate 

over long periods and also respond in a more consistent man- 

Figure 1. Histamine dose response evaluation in 30 randomly selected 

normal volunteers using acoustic rhinometry and anterior rhinomanometry. 

A comparison with mean values from a natural colds database of 

250 subjects. 

Figure 2. Measurement using the SRE 2000 PC acoustic rhinometer and 

the GM NR62 rhinomanometer. 1) Contoured nose adapter with gel at 

rim for leak-free fit, 2) Acoustic wave tube, 3) Pneumotachometer, 4) 

Stable head position using a shadow tracing technique.

Nasal histamine challenge model 47 

Data analysis 

To minimize the influence of nasal cycling, in all analyses, the 

sum of left and right nostril values were calculated for nasal airway 

volume (1-6.4cm) and nasal airflow (100 Pa) from acoustic 

rhinometry and rhinomanometry. Reproducibility of response 

to histamine was studied in subjects that complied with the 

inclusion criteria by computing the coefficient of variation over 

multiple visits for 5 and 15 minutes post challenge values. 

For subjects that showed good reproducibility (< 25% CV 

between visits), and were therefore likely candidates for a congestion 

panel, the level of congestion produced by histamine 5 

and 15 minutes post challenge was compared to a natural colds 

database of 250 subjects. To examine reproducibility, nasal 

volume and airflow were compared at first, second and last 

visits, and differences from visit 1 were calculated. In order to 

compare with published data of reproducibility (Van Wijk et al., 

1989), correlation was studied for 15 minutes post-challenge values 

at the second and last visits compared to the first using nasal 

volume and airflow. 

Figure 3. Study procedure. 

ner, as needed when attempting to establish a stable panel of 

responders. 

Subjects that complied were further recalled, on multiple occasions 

(at least 2), with a minimum interval of a week between 

visits. At every visit they underwent routine history and examination 

by the attending physician prior to the half hour acclimatization 

(25°C, 45-55%RH) in the measurement laboratory. 

Baseline measurements of left and right nostrils followed, using 

acoustic rhinometry and active anterior rhinomanometry 

performed in quick succession. Nasal challenge with histamine 

was then administered in each nostril as described above 

and measurements repeated 5 and 15 minutes post challenge 

(Figure 3). Observations of excessive sneezing or adverse effects 

were recorded. 

Figure 4. Distribution of variability in response to histamine in 32 normal 

subjects measured by the co-efficient of variation between visits. 

Nasal airflow (100 Pa) and nasal airway volume were measured 5 and 

15 minutes post challenge. 

RESULTS 

Subject disposition 

Thirtyseven of 69 (54%) normal subjects investigated over 2 

visits, did not meet the minimum criteria to qualify for further 

reproducibility testing. Of these, 12 non-compliant subjects 

were lost to follow up. Eight had fluctuating baseline values 

over visits (CV>15%), inadequate congestion with histamine 

(


Figure 6. Comparison of congestion induced by histamine with natural 

colds, using nasal airway volume and nasal airflow. 

Figure 5. Degree of nasal congestion induced by histamine in 23 subjects 

who showed good response reproducibility (

Nasal histamine challenge model 49 

showed significant nasal congestion symptoms and nasal occlusion 

(increased nasal airway resistance) with histamine. 

The use of a single 300µg dose of histamine diphosphate was 

dictated by the objective of matching obstruction produced in 

natural colds, which was determined from a preliminary histamine 

dose response study. The current study results further 

validate the dose selected since this data also compares well 

with the natural colds database. The dose is well within the range 

used in threshold type tests and is less than the supraphysiologic 

dose of 375µg histamine chloride (MW 184, equivalent to 

226µg histamine base compared to 108.6µg base in this study) 

discussed by Tonnesen and Mygind (1985). We compared 

response in our population with values extrapolated from dose 

response data for NAR in normals, <strong>report</strong>ed by Tonnesen and 

Mygind (1985). Thus, equivalent dose levels of histamine base 

(approximately 108µg) produced an average 50% increase (range 

27 - 70%) from baseline NAR (our data) compared to approximately 

35% increase based on Tonnesen and Mygind (1985). 

Study design, execution aspects 

Careful attention was paid to standardize challenge administration 

and measurements using acoustic and anterior rhinomanometry. 

Though nebulizers (Doyle et al., 1990), drops, filter 

papers infiltrated with actives (Hilberg et al., 1995) have been 

used, we opted for a well qualified metered dose spray device, 

an easy and frequently used method (Pirila et al., 1990; Van 

Wijk et al., 1989; Tonnesen and Mygind, 1985), which proved 

effective in this study as well. 

No subjective or objective methods to evaluate secretion and 

sneezing in response to histamine were used, since the objective 

was to specifically evaluate nasal obstruction produced by 

vascular changes, which were adequately measured by objective 

methods used in this study. In addition to nasal volume from 

acoustic rhinometry, we preferred to directly measure nasal airflow 

(at 100 Pa) from rhinomanometry, a variable that is normally 

distributed and more sensitive compared to NAR, which 

is a derived parameter. NAR, the most frequently used measure 

in challenge models, was however calculated for purpose of 

comparison with published data. Similar to Tonnesen and 

Mygind (1985), we examined response at two early time-points, 

5 and 15 minutes post challenge, since we expected immediate 

and short-lived responses. The intention with the 15 minute 

reading was to obtain a less variable measure which at the same 

time allows unhurried execution in a clinical trial setting. The 

duration of histamine effects were not evaluated in this study. 

Response and reproducibility: 

Finally, after excluding 10 subjects who did not wish to participate 

further, from 59 medically suitable volunteers, 23 (39%) 

showed a highly reproducible response to histamine. Since 

reproducibility over multiple visits was tested only in 32 subjects, 

this data was compared for nasal airway resistance with 

published data (Corrado et al., 1987). Whereas the median coefficient 

of variation was <strong>report</strong>ed as 38% by Corrado et al. (1987), 

our data showed less variability viz. 23%CV. This may be explained 

by the preliminary screening process that selected more suitable 

subjects in our study. Acoustic rhinometry showed less 

variability than airflow at 15 minutes post challenge and corroborates 

our previous experience and published <strong>report</strong>s. 

Also, a study of correlation between visits (first and second, first 

and last), similar to the analysis by Van Wijk et al. (1989), 

showed similar and strong correlation, especially for nasal volume, 

which appeared better. The minor differences in response 

over visits and similar correlation from first to second or last 

visit indicate that 2 visits are sufficient to evaluate reproducibility 

of response in subjects selected by the simple criteria used in 

this study. This also makes the model more feasible to run on 

an ongoing basis since new volunteers could be quite easily 

qualified. 

Congestion induced by the single dose level of histamine varied 

between subjects and reflected a distribution similar to natural 

colds. The models were comparable within 15% by both the 

dynamic measure of nasal ventilation and the anatomic measure 

of volume. We expect nasal blood vessels to be in a similar 

physical state under natural disease and induced conditions. 

Figure 7. Comparison of histamine induced congestion and natural 

colds models.


Decongestant effects are therefore likely to be correlated in the 

models, allowing the induced model to serve as a useful screening 

tool. The advantages of the induced clinical model lie in 

the more controlled conditions of testing and hence better sensitivity, 

ready availability of suitable volunteers (once developed), 

feasibility of cross-over designs, smaller sample size that 

also provides good statistical power. Combined, these factors 

would make this a rapid throughput, cost effective screening 

system for drug development projects. However, more understanding 

is needed of the combined effect of colds mediators 

compared to histamine alone on vascular pathophysiology, and 

also the influence of secretions, edema etc in the different 

models. Clearly the time-course of effects is different. The 

waning obstruction over a few hours with histamine challenge 

could be a limitation, unlike a more stable congestion level over 

short periods in the common cold (Figure 7). 

Future validation work for this induced nasal congestion model 

will include examining pharmacological effect (dose response) 

of a vasoconstrictor viz. a topical sympathomimetic drug and 

comparing with decongestion during natural common colds 

obtained using the same drug. Besides evaluation of decongestants, 

the model could have applications in studying antiallergy 

drugs and mechanisms of action. 

CONCLUSION 

A practical, reproducible method to induce nasal congestion 

similar to natural colds has been described using nasal histamine 

challenge. In future, this could be developed into a rapid 

screening system (model) for drug development work. 

9. Hilberg O, Jackson AC, Swift DL, Pedersen OF (1989) Evaluation 

of nasal cavity geometry by acoustic reflection. J Appl Physiol 43: 

523-536. 

10. Hilberg O, Grymer LF, Pedersen OF (1995) Nasal histamine challenge 

in nonallergic and allergic subjects evaluated by acoustic rhinometry. 

Allergy 50:166-173. 

11. Majchel AM, Baroody F, Kagey-Sobotka A, Lichtenstein LM, 

Naclerio RM (1993) Effect of oxymetazoline on the early response 

to nasal challenge with antigen. J Allergy Clin Immunol 92: 767- 

770. 

12. Mygind N (1982) Mediators of nasal allergy. Clin Immunol 70: 149- 

159. 

13. Parvez L, Erasala G, Noronha A (2000) Novel techniques, standardization 

tools to enhance reliability of acoustic rhinometry measurements. 

Rhinology: suppl. 16.: 18-29. 

14. Pirila T, Talvisara A, Alho OP, Oja H (1997) Physiological fluctuations 

in nasal resistance may interfere with nasal monitoring in the 

nasal provocation test. Acta Otolaryngol (Stockh) 117: 596-600. 

15. Tonnesen P, Mygind N (1985) Nasal challenge with serotonin and 

histamine in normal persons. Allergy 40: 350-353. 

16. Van Wijk RG, Mulder PGH, Dieges PH (1989) Nasal provocation 

with histamine in allergic rhinitis patients: clinical significance and 

reproducibility. Clinical and Experimental Allergy 19: 293-298. 

O. Hilberg 

Institute of Environmental & 

Occupational Medicine 

University of Aarhus 

Vennelyst Boulevard # 6 


Denmark 

Fax : +45-8942-6199 

Tel : +45-2087-8694 

ACKNOWLEDGEMENTS 

We wish to acknowledge the contribution of Ms. S. Aich- 

Dharap in preparing the manuscript and scientific team members 

including Mss R. Somane and S. Madhavan. 

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activity of H1 receptor antagonists assessed by nasal challenge. 

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4. Britton MG, Empey DW, John GC, McDonnell KA, Hughes DTD 

(1978) Histamine challenge and anterior nasal rhinometry: their use 

in the assessment of pseudoephedrine and triprolidine as nasal 

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Rhinology 22: 151-155. 

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measured by anterior rhinomanometry: reproducibility of the technique 

and the effect of topically administered antihistaminic and 

anti-allergic drugs. Br J Clin Pharmac 24: 283-292. 

7. Doyle WJ, Boehm S, Skoner DP (1990) Physiologic responses to 

intranasal dose response challenges with histamine, methacholine, 

bradykinin and prostaglandin in adult volunteers with and without 

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do not increase nasal reactivity. Clinical Allergy 16: 597-602.

Supplement, 16, 52-58, 2000 

Acoustic rhinometry in infants and children 

Per Djupesland 1 , Ole Find Pedersen 2 

1 

2 

Department of Otorthinolaryngolgoy, Ullevål University Hospital, 0407 Oslo, Norway 

Department of Environmental and Occupational Medicine, Building 260, Aarhus University, DK-8000, Aarhus, 

Denmark 

SUMMARY 

Acoustic rhinometry (AR), introduced a decade ago for assessment of the nasal airways of 

adults, has several attractive features relevant to application in a paediatric population. Its 

non-invasive nature, simplicity and rapidity are prime assets when examining infants and 

small children. Valid AR measurements can be obtained in a few seconds and require minimal 

co-operation. 

The striking consistency of AR studies of healthy subjects and the agreement with CT-derived 

and directly measured choanal dimensions are a strong indication of its reliability. Acoustic 

rhinometry optimised for infants and small children opens new perspectives and possibilities 

in the assessment of nasal airway dimensions and their relationship to pathological conditions 

in both the upper and the lower airways. 

The objective of this paper is to describe the advantages of AR in infants and children, but also 

point out its limitations and potential sources of error. Practical guidelines as to the measurement 

procedure and analysis and interpretation of AR-data are outlined. 

Key words: acoustic rhinometry, child, infant, nasal airway, nasal obstruction, pediatrics, 

rhinitis. 

INTRODUCTION 

The nasal airway is the natural and preferred respiratory route at 

all ages (Cole, 1993). In infants and animals, the elevated position 

of the larynx secures a functional separation of the airway 

and the oral alimentary tract. Whereas it enhances suckling and 

prevents aspiration, this anatomic configuration renders neonates 

particularly vulnerable to nasal obstruction. Both congenital 

and acquired nasal obstruction may cause severe, life-threatening 

respiratory distress in neonates (Djupesland et al., 1997). 

The subsequent gradual decent of the larynx, perquisite to 

accommodate human speech, will facilitate conversion to oral 

breathing. Still, oral breathing complements or replaces nasal 

respiration only if the nasal breathing becomes insufficient due 

to increased ventilation and/or obstruction of the nasal airway 

(Cole, 1993). 

The high incidence of upper respiratory tract infections (URTI) 

and allergies in childhood causes immune-activation and subsequent 

mucosal engorgement and hyperplasia of the abundant 

lymphatic tissues of the upper respiratory tract (Cole, 1993; van 

Cauwenberge et al., 1995). Thus, although nasal and nasopharyngeal 

obstruction contribute to snoring, mouth breathing and 

disturbed sleep at all ages, these pathologies are particularly 

common in early childhood. Disturbed sleep contributes to 

behavioural changes, reduced school performance, growth 

retardation and even cardiopulmonary changes in severe longstanding 

cases (Cole, 1993; van Cauwenberge et al., 1995). 

Evaluation of the upper airways 

Despite the obvious deleterious impact of upper airway obstruction 

in children as well as their parents, the investigative modalities 

suitable for assessment of the upper airway patency are 

limited. Although a very useful diagnostic tool in children, flexible 

endoscopy does not provide an objective measure of airway 

patency. Cost and complexity of modern imaging tech-niques 

such as CT and MRI limit their application in assessment of 

infants and children. Furthermore, in children, the requirement 

for co-operation also restricts the use of functional assessment 

of nasal and upper airway resistance by rhinomanometry (RM) 

(Crysdale and Djupesland, 1998). 

Acoustic rhinometry (AR), introduced a decade ago for assessment 

of the nasal airways of adults (Hilberg et al., 1989), have 

several attractive features relevant to application in a paediatric 

population (Djupesland and Lyholm, 1997). This paper will outline 

the particular advantages and potentials of AR in assessment 

of children, but also address its limitations and potential 

sources of error relevant to the practical application and interpretation 

of the results.

Acoustic rhinometry in infants and children 53 


Audible acoustic signals generated in a tubular probe wave tube 

are conducted via a nasal adapter to the nasal cavity under examination. 

The incident signal and its reflections from the nasal 

cavity are detected by a microphone within the sound wave 

tube. Resulting electrical signals are processed by analyzing 

software to provide a graphic display of cross-sectional area-distance 

relationships and a numeric description of minimum 

cross-sectional areas (MCA) and volumes between selected 

points in the nasal cavity (Hilberg et al., 1989) (Figure 1). We 

prefer a linear to a logarithmic display because it allows direct 

visual dimensional comparison between curves. Furthermore, 

proper dimensional matching of the sound wave tube and nose 

adapter to the nasal airway dimensions, virtually eliminates the 

need for logarithmic display. 

Figure 1. Result of reflection to area transform. 

Drawing illustrating the course of the acoustic pathway (AP) position of 

the inferior turbinate, middle turbinate, anterior and posterior nasal spine 

(ANS/PNS), epipharynx (EP) and their relationship to the features of an 

acoustic rhinogram from a one year old infant. (MCA1 is the cross-sectional 

area corresponding to the internal isthmus, MCA2 correspond to 

the head of the inferior turbinate, and VOL4 is the volume of the anterior 

4 cm). 

Acoustic rhinometry in children 

AR represents a quick and non-invasive method for objective 

assessment of the nasal airways and requires minimal co-operation 

from the child. In the early nineties AR was applied to 

both infants (Buenting et al., 1994; Pedersen et al., 1994) and 

pre-school children (Riechelmann et al., 1993), using modified 

adult probes. Although rhinological authorities debate the relative 

advantage of RM and AR in adults, few dispute the potentials 

of AR in small children in whom RM is not an option. In 

fact, the smaller dimensions of the nasal airways in infants permit 

application of a higher maximum band-width frequency, 

thus significantly improving the accuracy of the acoustic measurements 

(Djupesland and Lyholm, 1997; Djupesland and 

Lyholm, 1998). However, in order to benefit from this unique 

feature and achieve optimal results it is essential that all components 

of the rhinometer are matched to the nasal airway 

dimensions of the age group in question (Djupesland and 

Lyholm, 1998). If such a matching of the equipment properties 

takes place for the study of children the resolution can be 

improved and the accuracy and validity of AR can be substantially 

improved (Cole et al., 1997) (Figure 1). 

Advantages of AR 

Valid AR measurements can be obtained in a few seconds and 

requires minimal co-operation. This is of paramount importance 

to its application in infants and children. Combined with 

its non-invasive nature, mobility and small size of the equipment 

makes it better suited for repeated examination of infants 

and small children. If continuous movement and crying impede 

data acquisition, measurements can if necessary easily be obtained 

during sleep and in any body position (Djupesland and 

Lyholm, 1997). 

The acoustic rhinogram provides a description of the degree 

and location of the obstruction, physiological changes and 

responses to various types of intervention. The high correlation 

between AR derived dimensions at the choanal aperture and 

dimensions obtained by direct in-vivo and post-mortem measurements 

(Corsten et al., 1996; Wolf et al., 1993), in models 

(Djupesland, 1999; Buenting et al., 1994) and on CT-scans 

(Corsten et al., 1996) is an indication of its validity in infants. 

The small size of the sinuses at birth and the moderate development 

childhood (Wolf et al., 1993; Corsten et al., 1996) reduce 

the potential artefacts due to loss to the sinuses which does 

represents a restriction in adults (Hilberg and Pedersen, 1996). 

Equipment suitable for neonates may not be suitable for infants 

above 1-2 years of age (Djupesland et al., 1999b; Djupesland and 

Lyholm, 1998). When the children reach an age of 6-10 years, 

the adult sound wave tubes seem appropriate. 

Limitation of AR 

The prime limitation of AR is its static nature. Ventilation in a 

dynamic process and the ventilatory characteristics change 

rapidly with growth and maturation in childhood. Furthermore, 

the cross-sectional areas and volumes provided by AR do not 

describe the shape of the cross-sectional areas. The aerodynamic 

properties of an orifice is strongly influenced by it shape, 

rate of airflow and the prevailing flow regime (Hey and Price, 

1982). Laminar, traditional and turbulent flow can occur simultaneously 

in different parts to the nasal passage and complicate 

the interpretation of cross-sectional areas in terms of resistance. 

Finally, the non rigidity of the alas may induce dynamic collapse 

of the compliant part of the external nose which is not recognised 

by the static measurements (Cole et al., 1997). 

The respiratory induced pressure changes may also represent a 

problem in small children (Djupesland and Lyholm, 1998;

54 Djupesland, Pedersen et al. 

Tomkinson and Eccles, 1995). In neonates, the refectory brief 

pause in respiration observed secondary to the tactile stimulus 

of the nose adapter, reduce this problem. Alternatively, averaging 

of curves obtained at different phases of several respiratory 

cycles can be used (Djupesland and Lyholm, 1998). In older 

infants and small children not able to voluntarily hold their 

breath or breathe orally, the use of an artificial oral airway may 

be of help. This problem could also be minimised by use of 

open rhinometric sound wave tubes, but in that case flow 

through the tube may change the sound velocity and cause error 

especially in the distance measurements. 

The basic algorithms used in AR assume negligible sound loss. 

Behind narrow constrictions this may not be true and result in 

underestimation if the true dimensions if they exceed the MCA 

by a factor of 3-4 (Djupesland and Lyholm, 1998). Whereas studies 

employing adult probes refer to a lower limit of MCA for 

accurate determination of posterior dimensions ranging 

between 0.2 and 0,7 cm 2 (Hilberg et al., 1989; Riechelmann et 

al., 1993), validation of the infant probe showed that this value 

is 0.05cm 2 (Djupesland and Lyholm, 1998). Sound wave tubes 

optimised for the nasal airway of guinea pigs are able to differentiate 

even smaller dimensions (Kaise et al., 1999). In case of 

mucosal inflammation, congestion fortunately occurs primarily 

in the posterior part of the nasal cavity reducing the risk of artefacts. 

Sources of error 

In addition to the importance of awareness of the limitations 

outlined above, focus must be drawn to some potential sources 

of error which can jeopardise the results. Early studies used 

conical nosepieces which have obvious risks of expanding the 

anteriorly located valve area. Application of anatomical adapters 

have been found to reduce the MCA by 10-15% (Roithmann et 

al., 1995). Secondly, even a minor sound leakage between the 

rim of the nostril and the adapter may cause severe overestimation 

of posterior dimension. Awareness and proper training is 

essential to avoid these errors. In addition the repeated reapplication 

of the sound wave tube until three independent curves 

with a CV% of less than 5% is obtained will reduce the risk of 

systematic error considerably. Such a selection of curves, however, 

may be seriously biased, unless the criteria for rejection of 

curves are strictly defined. Finally, external noise, pressure and 

temperature can also affect the AR measurements (Djupesland 

and Lyholm, 1998; Tomkinson and Eccles, 1995; Tomkinson 

and Eccles, 1996) and proper action should be taken to avoid 

and reduce such influences. 

AR in infants 

The striking consistency of AR studies of healthy neonates in 

three studies published by independent groups and the agreement 

with CT-derived and directly measured choanal dimensions 

are a strong indication on it reliability in infants (Djupesland 

et al., 1999b; Djupesland and Lyholm, 1998). The mean 

MCA in neonates of 0.1cm is doubled by the age of one (Djupesland 

and Lyholm, 1998). At birth the MCA is located to the 

Figure 2. Graph showing the relative rhinometric dimensions at different 

ages. 

The curves for neonates and one-year old infants are the mean unilateral 

curves from the same 39 infants. The curve from the 8 year old 

child and the adult represents a typical unilateral curves. The measurements 

of the infants were performed with an optimised infant sound 

wave tube (RhinoMetrics A/S, Denmark), whereas the curves for the 

child and the adult were performed with an adult sound wave tube with 

anatomic nose adapters. The large difference at the origin of the curves 

is partly due to the difference in sound wave tube dimension (Infant 

sound wave tube: 0.13 cm 2 , adult sound wave tube: 1.2 cm 2 ). The vertical 

lines indicate the transition to the epipharynx. 

internal isthmus and its value was found to correlate significantly 

with the circumference of the head (Djupesland and 

Lyholm, 1998). With age and in response to infection and inflammation 

the second constriction corresponding to the head 

of the inferior turbinate, becomes more evident and the rhinometric 

curve assumes a shape similar to adults (Riechelmann et 

al., 1993; Djupesland and Lyholm, 1998) (Figure 2). In one year 

old infants having experienced a recent URTI, the volumes posterior 

to the internal isthmus was significantly reduced compared 

to healthy controls after adjustment for gender and AR 

dimension at birth (Djupesland and Lyholm, 1998). The acoustically 

inferred depth of the nasal cavity in neonates of 4-5 cm 

corresponds with dimensions measured on lateral radiograms 

and CT scans (Djupesland et al., 1997) and the growth is very 

limited the first years of life (Djupesland and Lyholm, 1998) 

(Figure 2). These finding further support the validity of AR in 

infants. 

AR can assist in the diagnosis of acquired and congenital nasal 

obstruction in infants (Djupesland et al., 1997) and craniofacial 

anomalies (Kunkel et al., 1997) and its potential role in the diagnosis 

and follow-up of such conditions have been described. AR 

has proven useful to evaluate the relationship between nasal 

dimensions and pulmonary function, both in healthy neonates 

(Djupesland and Lodrup Carlsen, 1997) and in infants challenged 

with histamine (Kano et al., 1994). The technique is also


promising as a method to evaluate normal nasal physiology in 

infants. It may also assist in determining the role of nasal 

obstruction as a contributing factor in sudden infant death syndrome 

as measurements can be performed repeatedly both 

during wakefulness and during sleep. The infant sound wave 

tube used in this study (RhinoMetrics A/S, Denmark) has been 

found to be suitable also for examination of premature infants, 

but no systematic studies have so far not been published. 

AR in older children 

The number of AR studies in older children is limited (Fisher et 

al., 1995b; Ho et al., 1999; Fisher et al., 1995a; Riechelmann et 

al., 1993; Zavras et al., 1994). One obvious reason is the lack of 

adequate equipment for children 1-10 years of age. In 1993, Riechelmann 

et al. (Riechelmann et al., 1993) published a study of 

37 pre-school children (3-6 years) using a modified adult probe. 

By comparing the rhinograms from infants (Djupesland and 

Lyholm, 1998), it is evident that the second constriction corresponding 

to the head of the turbinate gradually takes over as the 

flow-limiting segment. All of the 94 healthy neonates (Djupesland 

and Lyholm, 1997), 37 out of 39 one year old infants (Djupesland 

and Lyholm, 1997) and 15 out of 17 infants aged 1-16 

(Kano et al., 1994) had the MCA located corresponding to the 

internal isthmus (MCA1) the DMCAs varied between 8 and 

10mm. Half of 3-6 year old children (Riechelmann et al., 1993) 

and two thirds of 6-11 years old children (Djupesland, unpublished 

data) had MCA located at a site corresponding to the 

head of the inferior turbinate. A recent study evaluating 183 

children aged 1-11 years without nasal symptoms (Ho et al., 

1999) did unfortunately not, distinguish between these two 

anterior minima, thus limiting the value of the data <strong>report</strong>ed. 

Application of an adult probe and poor impedance matching 

between the nostril and the perforated cylindrical glass nosepiece 

used, may explain why the anterior minimum (MCA1) was 

not recognised as a separate entity. The MCA <strong>report</strong>ed at different 

ages in this study (Ho et al., 1999), probably represent an 

unknown intermixture of MCA1s and MCA2s (Djupesland and 

Lyholm, 1998). This assumption is further supported by the 

<strong>report</strong>ed mean distance to the MCA (DMCA) of 14 mm (Ho et 

al., 1999), which is actually the mean of the DMCAI (8mm) and 

DMCA2 (20mm) <strong>report</strong>ed in the 3-6 -year old children (Riechelmann 

et al., 1993). Furthermore, it provides an logic explanation 

to the unexpected large MCA of 0,43cm 2 <strong>report</strong>ed by HO 

et al. (Ho et al., 1999). They are actually <strong>report</strong>ing the MCA2, 

which in infants has been found to larger that in older children 

(Djupesland and Lyholm, 1998). 

Growth and maturation of the nasal airway 

Repeated infections, development of allergies and maturational 

changes in combination, cause hypertrophy of the turbinates 

and a more prominet MCA2. This will eventually change the 

position of the absolute MCA from MCA1 to MCA2, which is 

the typical configuration in adults. This may explain the 

increasing incidence of mouth breathing and high nasal resistance 

in children in this age group (Parker et al., 1989; Cole, 

1993; Warren et al., 1990). In a group of 20 older children (7-16 

years) Zavras et al. (Zavras et al., 1994) <strong>report</strong>ed significantly 

reduced nasal volumes in the ten children with a history of 

chronic mouth breathing. 

The nasal dimensions in adults appears to be approximately 6 

times larger than those of neonates and 3 times the dimensions 

of one-year old infants (Buenting et al., 1994; Djupesland and 

Lyholm, 1997; Djupesland and Lyholm, 1997; Pedersen et al., 

1994). The mean acoustically derived dimension in a group of 

healthy children aged 6-10 years (TMCA = 0.77 cm 2 , TVOL0-5 

= 6.0 cm 3 (Djupesland, unpublished observations) examined 

with an adult sound wave tube using a small anatomic nose 

adapter, were approximately half of the mean adult dimensions 

obtained with anatomic nose adapters (TMCA=1,3 cm 2 , 

TVOL0-5=12 cm 3 ) (Roithmann et al., 1997; Djupesland et al., 

1999a). In this age group, the configuration of the rhinogram 

was similar to that of adults (Figure 2). The acoustically derived 

depth of the nasal cavity of 4-5 cm in infants (Djupesland and 

Lyholm, 1998; Pedersen et al., 1994), 6 cm in at 6-10 year olds 

(Qian et al., 1999), and 7-9 cm in adults (Hilberg et al., 1989) 

(Figure 2). The length of the nasal cavity has been measured by 

X-ray in 146 Japanese children aged 1.8 to 15.8 years, attending 

an ENT clinic (Yamagiwa, 1999). The length in mm was found 

to be defined by the equation (1.074 × age (years) + 40.56 mm), 

corresponding to 4.2 cm at one year of age and 5.1 cm at the age 

of 10. The radiological dimension at one year of age correlates 

well to the length derived from the acoustic rhinogram, <strong>report</strong>ed 

in 39 Caucasian infants (Djupesland and Lyholm, 1997), but 

smaller that the acoustically derived nasal length of 6.1 cm 

obtained in six healthy children aged 5-10 years (Qian et al., 

1999). The smaller growth with age measured on radiographs 

may in part be due to racial differences and to symptomatic 

nasal disease in the children studied with X-ray (Yamagiwa, 

1999). The difference can be explained by a combination of 

differences in the nature of the different measurement modalities 

and the increasing curving of the acoustic pathway with age 

and maturation of the nasal morphology. Thus, the length 

between two reference points measured along this curved pathway 

will necessarily become slightly longer than when measured 

along a straight line on lateral radiograms. 

The mean minute ventilation increases from 1,2 L/min at birth 

to 2.4 L/mIn at one year and is doubled again to 5 L/min in 

adults (ATS-ERS statement, 1993; Cole, 1993). The change in 

tidal volume and respiratory rate and the change in position and 

location of the flow-limiting segment in the nose, make interpretation 

of dimensions in terms of resistance difficult. Thus, 

given the rapid maturational changes in both nasal dimensions 

and ventilatory characteristics in childhood, systematic studies 

establishing normative values for nasal airway dimensions in 

relation to age and body size, are required for optimal clinical 

use of AR in children. 

Measurement procedure in infants and children 

The particular challenge of measuring non co-operating infants 

and small children have been described above. It is important to


realise that exercise and vigorous crying can affect the nasal 

mucosa and consequently the AR results. Provided the child 

remains quiet and breathes orally or holds its breath, the practical 

procedures for AR measurement are similar to those of 

adults. Some studies advocate fixation of the sound-wave tube 

as well as stabilisation of the head (Roth et al., 1996; Silkoff et 

al., 1999). Similar reproducibility has, however, been obtained 

without instrument fixation (Djupesland et al., 1999a). We discourage 

its use, particularly in children, because of the increased 

time requirement. Head stabilisation may be advantageous 

in older children and adults, but is not necessary. Furthermore, 

both head and instrument fixation severely reduces the speed, 

flexibility and mobility of AR which are prime assets of the 

method (Djupesland et al., 1999a). Regardless of the practical 

setting, generous, gentle application of the anatomical adapter is 

essential to minimise distortion. In addition, anatomical nose 

adapters will help to maintain a stable angle between the sound 

wave tube and the nose. Some changes in this angle may occur 

with the symmetrical rounded nose adapters used in infants, but 

the effect appears to be negligible provided distortion is avoided 

and a tight seal maintained (Djupesland and Lyholm, 1997; 

Djupesland et al., 1999b). Repeated application of sealing gel, 

particularly at the posterior margin of anatomical nose adapter, 

may be required in some subjects to prevent sound leaks. Blinded 

measurements will make it possible to detect and avoid systematic 

error. Provided distortion is avoided, superimposed 

traces are more likely to be correct. We recommend that measurements 

should be performed until 3 traces with


respiratory characteristics. The technique is still young and further 

studies and development of the technique is required to 

improve its diagnostic and predictive value in paediatric 

research and clinical practice. 

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41. Wålinder R, Norbäck D, Wieslander G, Smedje G, Erwall C (1997) 

Nasal congestion in relation to low air exchange rate in schools. 

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724-727. 

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nasal cross-sectional area and respiratory mode in children. Laryngoscope 

100: 89-93. 

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sinuses in children: implications for paranasal sinus surgery 

[Review] [20 refs]. Ann Otol Rhinol Laryngol 102: 705-711.


44. Yamagiwa M (1999) Nasal cavity lenght in pediatric patients with 

otorhinolaryngological diseases. Rhinol Suppl 15: 63-65. 

45. Zavras AI, White GE, Rich A, Jackson AC (1994) Acoustic rhinometry 

in the evaluation of children with nasal or oral respiration. 

J Clin Pediatr Dent 18: 203-210. 

Per G Djupesland 

Department of Otorhinolaryngology 

Ullevål University Hospital 

0407 Oslo 

Norway 

Tel: +47-2211-8570 

Fax: +47-2211-8555 

email: per.djupesland@ioks.uio.no

Supplement, 16, 59-64, 2000 

Acoustic rhinometry in epidemiological studies - 

Nasal reactions in Swedish schools 

Robert Wålinder 1 , Dan Norbäck 1 , Gunilla Wieslander 1 , Greta Smedje 1 , 

Claes Erwall 2 , Per Venge 3 

1 

2 

3 

Department of Medical Sciences/Occupational and Environmental Medicine, University of Uppsala, Sweden 

Department of Oto-Rhino-Laryngology and Head and Neck Surgery, University Hospital, Uppsala, Sweden 

Department of Clinical Laboratory Sciences, University Hospital, Uppsala and Asthma Research Center, 

University of Uppsala, Sweden 

SUMMARY 

A cross-sectional study was performed on the relationships between hygienic measurements 

and nasal investigations in 234 personnel in 12 primary schools in mid-Sweden. Hygienic data 

included building characteristics, measurements of indoor air pollutants, air change rate, temperature 

and humidity. Clinical examinations included symptom <strong>report</strong>s, acoustic rhinometry 

and nasal lavage, with the determination of biomarker levels for eosinophil cationic protein 

(ECP), lysozyme, myeloperoxidase (MPO) and albumin. Subjective nasal obstruction was increased 

in schools with mechanical ventilation (adjusted prevalence OR=2.0; 95 CI 1.1-3.7) and 

subjects <strong>report</strong>ing nasal obstruction had higher levels of dust in the classroom, compared to 

those not <strong>report</strong>ing this symptom (p= 0.008 by Mann-Whitney U-test). Congruently, a decreased 

nasal patency measured by acoustic rhinometric minimum cross-sectional areas 

(MCA1 and MCA2) was related to the use of mechanical ventilation (p=0.008 and p= 0.02 

respectively, by Mann-Whitney U-test), dust levels (p=0.03 and p

60 Wålinder et al. 

Table 1. Absolute frequencies of personal characteristics. 

Personal 

characteristics 

Absolute 

frequency 

(N=234) 

Female 194 

Smoker 35 

Atopy 54 

Asthma 19 

the introduction of new synthetic materials and building techniques. 

Polyvinyl chloride (PVC) flooring with plasticizers may 

result in emissions of volatile compounds to the indoor air 

(Gustafsson and Lundgren, 1997) causing respiratory disease 

(Jaakkola et al., 1999). The use of flat roofs has increased the 

risk of water leakage and dampness in the floor construction has 

been a problem in concrete slab fundaments (Amunduson et 

al., 1997; Svennerstedt, 1983). Building dampness has been 

associated with an increase in respiratory symptoms (Brunekreef, 

1992; Dales et al., 1991). 

Most epidemiological studies on possible health effects of building 

related factors have dealt with symptom <strong>report</strong>s only, not 

with clinical signs. Recently, objective methods to study environmental 

effects on the upper airways have been developed. By 

acoustic rhinometry measurable effects on the degree of nasal 

patency have been demonstrated for temperature changes and 

volatile organic compounds (Lundqvist et al., 1993; Möl-have et 

al., 1993). Also nasal lavage is a well-documented technique for 

the study of a biomarker response in the nasal mucosa (Peden, 

1996). Biomarkers of inflammation, plasma exudation and glandular 

secretion have been related to different exposures, such as 

building dampness (Wieslander et al., 1999), formaldehyde 

(Pazdrak et al., 1993) and volatile organic com-pounds (Koren et 

al., 1992). In the present study, a battery consisting of four biomarkers 

was chosen in order to cover up several physiological 

mechanisms of the nasal mucosa. In cytological analyses of nasal 

lavage fluid about 90% of the leukocytes are neutrophil granulocytes 

(Pipkorn et al., 1989) and myeloperoxidase (MPO) has been 

shown to be a specific biomarker for the activity of neutrophil 

granulocytes (Schmekel et al., 1990), thereby being a marker of 

airway infection. The level of eosinophil cationic protein (ECP) 

in lavage is a marker for eosinophil activation (Venge et al., 

Table 2. Absolute frequencies of schools and subjects across the 

building characteristics. 

Number of schools Number of subjects 

Building characteristics N=12 N=234 

Mechanical ventilation 8 173 

Flat roof 1 18 

Concrete slab fundament 4 71 

Wood construction 4 74 

PVC floor carpeting 7 127 

Wall-to-wall carpets 0 0 

Signs of water-damage 1 18 

Wet mopping used 9 160 

Urban vicinity 6 207 

1989), presumably to allergen exposure. Lysozyme was considered 

a marker of the overall mucosal secretory activity (Raphael 

et al., 1989). The albumin level is an indicator of a mucosal 

vasomotor response with plasma exudation. 

In the present paper we make a synthesis of results from 4 parts 

of a study on the school environment, investigating nasal effects 

of: ventilation (Wålinder et al., 1998), cleaning routines (Wålinder 

et al., 1999), building characteristics (Wålinder et al., 2000) 

and indoor air pollutants (Norbäck et al., 1999). Our hypothesis 

states that a physiological response can be measured in the 

upper airways due to certain indoor factors and exposures; type 

of ventilation, air change rate, temperature, building factors 

associated with water-damage (flat roof and concrete slab fundament) 

or chemical emissions (PVC carpeting), 

cleaning frequency, dust level, and indoor air pollutants (formaldehyde, 

nitric oxides, carbon dioxide, molds, bacteria, pet 

and mite allergens). The protocol of the study was approved by 

the Ethics Committee of the Medical Faculty of Uppsala University. 

MATERIAL AND METHODS 

Subjects 

The source population comprised primary school personnel in 

the municipality of Uppsala. From 12 randomly selected 

schools, 279 persons working at least 20 hours per week in the 

school building were invited to participate in the study. In all, 

234 persons (84%) participated. Personal factors were assessed 

via an interview and information on nasal symptoms the week 

prior to the medical investigation was gathered by means of a 

self-administered questionnaire. The set of symptoms included 

four questions on nasal symptoms: nasal obstruction, discharge, 

itch and sneezing. The mean age of the school personnel was 

46 years and the distribution of personal characteristics in the 

12 schools are shown in Table 1. 

Buildings 

The technical investigation consisted of a building survey and 

technical measurements. The measurements included room 

temperature and indoor levels of carbon dioxide (CO 2 ), nitrogen 

dioxide (NO 2 ), formaldehyde and other volatile organic compounds 

(VOC). Detailed descriptions of these measurements 

have been presented elsewhere (Smedje et al., 1997b). Settled 

dust was collected as a mixed sample via standardized vacuum 

cleaning for 4 minutes, equally distributed between desks, chairs 

and the floor. The dust collected (mg/sample) was weighed after 

sieving through a filter with a porosity of 300 µm. Eight out of 

twelve schools had mechanical ventilation systems. There was 

one school with a flat roof and in this school there were also 

signs of earlier water leakage from the roof. Four schools were 

classified as constructed of wood, having both outer and inner 

walls of wood. Three out of these four schools also had wood 

facing. No school had any textile wall-to-wall carpets in the classrooms. 

Six schools had only PVC floor material, whereas the 

other six had linoleum carpets, or both. The distribution of buil-

Nasal reactions in Swedisch schools 61 

Table 3. Arithmetic means with absolute deviations for hygienic measurements 

in the 12 schools. 

Indoor 

ArithmeticAbsolute 

measurements mean deviation 

Air change rate (ac/h) 1.9 0.5-5.2 

Temperature (°C) 22.5 21.5-24.5 

Relative humidity (%) 38 19-54 

Settled dust (mg/sample) 109 20-180 

Respirable dust (µg/m 3 ) 19 12-32 

Formaldehyde (µg/m 3 ) 9.5 3-16 

Nitrogen dioxide (µg/m 3 ) 5.1 2-11 

Carbon dioxide (ppm) 1150 720-1620 

ding characteristics among the schools are presented in Table 2 

and the technical measurements in Table 3. 


Acoustic rhinometry (Rhin 2000, wideband noise, continuously 

transmitted, S.R. Electronics, Denmark) was performed in the 

school building under standardized forms. It was performed sitting 

after 5 minutes rest and at least 1 hour in the building. By 

means of acoustic reflection the minimum cross-section areas 

(MCA) on each side of the nose were measured from 0 to 22 

mm (MCA1) and from 23 to 54 mm (MCA2) from the nasal 

opening. Also, the volumes were measured at the same distances 

(VOL1 and VOL2). The mean value was calculated from 

three subsequent measurements on each side of the nose and 

data on nasal dimensions are presented as the sum of the values 

for the right and the left side. 

Nasal lavage 

Lavage of the nasal mucosa was done with a 20-ml plastic syringe 

attached to a nose olive. In the lavage fluid the concentrations 

of eosinophil cationic protein (ECP), lysozyme, myeloperoxidase 

(MPO) and albumin were measured. The methods 

of the lavage technique have been described elsewhere (Wålinder 

et al., 1998). 

Statistical analysis 

The SPIDA statistical package was used (the Statistical Laboratory, 

Macquarie University, Australia) (Grebski et al., 1992). 

The Kendall’s ta rank correlation coefficients were applied to 

investigate the correlation between two variables which can be 

expressed in a rank order. For comparisons of the distributions 

between two groups ( i.e. flat roof, yes/no), the Mann-Whitney 

U-test was used. Multiple linear or logistic regression was used 

to control for potential confounders: age, gender, smoking 

habits, atopy, urban vicinity of the school and room temperature. 

In all statistical analyses, two-tailed tests and a 5% level of 

significance were applied. 

RESULTS 

Nasal symptoms 

Self-<strong>report</strong>ed nasal symptoms were common with a prevalence 

of 50% <strong>report</strong>ing at least one nasal symptom the week prior to 

the investigation. Nasal obstruction was most common (40%). A 

significant difference in the amount of dust in the classroom 

was observed for the subjects <strong>report</strong>ing nasal obstruction (118 

Table 4. Medians and interquartile ranges for nasal parameters across 6 dichotomized building characteristics. P-values in parentheses by Mann- 

Whitney U-test. 

Nasal Mechanical ventilation Flat roof Concrete slab fundament Wood construction PVC floor Wet mopping 

Parameter Yes No Yes No Yes No Yes No Yes No Yes No 

MCA1 a 0.88 0.7-1.0 0.95 0.8-1.1 0.84 0.7-0.9 0.91 0.8-1.1 0.89 0.8-1.0 0.92 0.8-1.1 0.85 0.7-1.0 0.92 0.8-1.1 0.84 0.7-1.0 0.95 0.8-1.1 0.86 0.74-1.0 0.96 0.86-1.2 

(p=0.008) (p=0.11) (p=0.36) (p=0.066) (p


Table 5. Kendall’s tau correlation coefficients for the relations between nasal parameters on one hand, and cleaning routines and indoor pollutants on 

the other. 

Frequency of Frequency of Settled dust Formaldehyde Nitrogen 

Nasal floormopping deskcleaning (µg/sample) (µg/m 3 ) dioxide 

parameter (times/week) (times/week) (µg/m 3 ) 

MCA1 a 0.09 (p=0.049) 0.18 (p

Nasal reactions in Swedisch schools 63 

consistent pattern of relationships for cross-sectional areas than 

for volumes, probably due to a lower inter-individual variability 

(Corey et al., 1998; Grymer et al., 1991) and intra-individual 

variability (Wålinder et al., 1997) for areas than for volumes was 

found. In a study investigating nasal cavity dimensions there 

were significant differences between healthy controls versus 

patients having either mucosal or structural abnormalities of the 

nose. After mucosal decongestion the differences disappeared 

between the healthy controls and the patients having mucosal 

abnormalities, but remained for structural abnormalities (Roithmann 

et al., 1995). In a previous study we also demonstrated 

that the difference in nasal cavity dimensions related to the level 

of indoor air pollutants is due to a mucosal swelling, based on 

the observation that the difference in nasal patency can be 

eliminated by the application of adrenergic nasal spray to the 

mucosa (Wålinder et al., 1997). 

It has been demonstrated that in Scandinavian schools there is 

widespread contamination by cat and dog allergens (Munir et 

al., 1993; Smedje et al., 1997a) and sometimes mite allergens 

(Einarsson, et al., 1995; Smedje et al., 1997a). Our findings indicate 

that actual dust levels in Swedish classrooms can affect the 

occurrence of nasal obstruction among school personal. We 

could also demonstrate positive effects of cleaning, with a relation 

between the cleaning frequency of floors and desks and 

nasal patency. 

Also the ventilation in schools has been neglected, and a recent 

study has shown that about 80% of Swedish classrooms have 

inadequate ventilation (Smedje et al., 1997b). An increased risk 

of sick building symptoms has been shown for buildings with a 

poor outdoor air supply (Godish and Spengler, 1996). Other studies 

have demonstrated that sick building symptoms are influenced 

by the type of ventilation, showing higher prevalence of 

symptoms in buildings with mechanical ventilation (Mendell, 

1993). In the present study, 11 of 12 schools did not fulfill the 

requirements of the current Swedish ventilation standard, and 

the results indicate that both a low air exchange rate and mechanical 

ventilation systems can be associated with reduced nasal 

patency and an inflammatory biomarker response. This is 

somewhat contradicting, since naturally ventilated schools on 

average have lower air exchange, but it is possible that insufficient 

maintenance of mechanical air supply ducts and filters 

have caused accumulation of particulate contaminants. 

Factors related to an increased risk of water-damage, flat roof 

and concrete slab fundament (Einarsson et al., 1995; Wickman 

et al., 1992), were related to an increase of the inflammatory 

markers ECP and lysozyme. In this random material of 12 

schools there were signs of water leakage from a flat roof construction 

in one school, and four schools had a concrete slab 

fundament. Earlier studies have shown that building dampness 

in day care centers may influence the occurrence of ocular and 

respiratory symptoms (Jaakkola et al., 1993; Ruotsalainen et al., 

1995; Taskinen et al., 1997). 

We also found a relation between increased lavage levels of 

ECP and lysozyme and PVC floor materials. Plasticizers used in 

the synthesis of PVC may be released or hydrolyzed and thereby 

releasing irritating chemicals to the indoor air (Gustafsson 

and Lundgren, 1997) with an increased risk of airway obstruction 

(Jaakkola et al., 1999). 

Also the indoor concentrations of formaldehyde and nitrogen 

dioxide were positively related to the lavage levels of ECP and 

lysozyme. An increase of eosinophil granulocytes and albumin 

in nasal lavage have been demonstrated at experimental exposure 

to higher concentrations of formaldehyde (Pazdrak et al., 

1993). There is also evidence of a potentiating effect of nitrogen 

dioxide on asthmatic symptoms as well as an enhanced response 

to inhaled allergens (Strand et al., 1996; Tunnicliffe et al., 

1994). 

In conclusion the hypothesis was confirmed that some building 

related factors and exposures could be related to certain physiological 

responses of the upper airways, at the group level. A 

multifactorial pattern was revealed with upper airway effects 

related to ventilation, dust, dampness and certain indoor air pollutants. 

Though significant, most differences in the present 

study were small, and it remains to show if the observed reactions 

have long term health effects, or if they should be considered 

as transient normal physiological responses. 

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Robert Wålinder 

Clinical Physiology 

University Hospital 

S-751 85 Uppsala 

Sweden 

fax: +46-18-611-4154 

e-mail: robert.walinder@medsci.uu.se

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