Biphasic Cuirass Ventilation

Title slide
Biphasic Cuirass
Ventilation
The Hayek Oscillator and
RTX Respirator

BCV Summary
-Biphasic Cuirass Ventilation (BCV) is often the ideal
ventilator as it:
a) Provides complete ventilation to patient
b) Is non-invasive
c) Works in a physiological way, in that it:
i) works in the way that the lungs work most efficiently by
actively controlling both phases of the respiratory cycle
ii) Provides even ventilation for patient
iii) Helps to maintain and redevelop the respiratory muscles
which often wither and waste with respiratory failure and
mechanical ventilation
iv) Improves cardiac output

BCV Summary
-Biphasic Cuirass Ventilation (BCV) is often the ideal
ventilator as it:
d) Provides an efficient method of weaning from PPV
e) Assists patient to remove secretions which are a symptom
of most respiratory diseases, aggravating the condition of
these patients
f) Can begin to provide treatment for patients before their
condition deteriorates and hospitalisation is required
g) Allows for continuity of treatment for patients in hospital,
at home, in transport and in emergency situations
h) Is simple to use and comfortable for the patient

BCV Summary 2
-Although BCV uses a cuirass, and has an active
negative phase
BCV IS NOT NEGATIVE PRESSURE VENTILATION
-Although BCV has an active positive phase,
BCV IS NOT POSITIVE PRESSURE VENTILATION
-BCV is external, controls both respiratory phases
actively, can work at low and high frequencies and
generally keeps the benefits of the differing types
of mechanical ventilation whilst avoiding most of
their disadvantages

Treating Respiratory Failure –
Mechanical Ventilation
The Ideal Ventilator (1):
• Should replicate the spontaneous breathing
pattern while achieving adequate ventilation
• Should be non-invasive
• Should preserve the normal intrathoracic
pressure and whilst not compromising
circulation
(Cont.)

Treating Respiratory Failure –
Mechanical Ventilation
The Ideal Ventilator (2):
• Should facilitate the clearance of secretions
• Should be therapeutic in maintaining or
improving the patient‟s condition (e.g.
maintaining the respiratory muscles)
• Should be user friendly to:
a) the patient, in terms of comfort
b) the operator, in terms of ease of use

Negative Pressure Ventilation
Iron Lung
(1843)
The First Workable Iron Lung
(1847)
The Motorized Iron Lung
(Late 1920‟s)
Dalziel
Woillez
Drinker &
Emerson
First Cuirass NPV
Drinker
(1939) & Collins

Negative Pressure Ventilation
Woillez‟s “Spirophore”
(1876)
Breuillard‟s
“BathCabinetRespirator”
(1877)

Negative Pressure Ventilation
Inspiratory active (chest inflation to above FRC)
Expiratory passive (passive chest recoil to FRC)

Tank Ventilators/The Iron
Although tank ventilators are effective in normal
lungs, they are far less effective in sick lungs. The
disadvantages of the Iron Lung include:
• They are cumbersome
Lung
• Limited access to patients
• Aggravated heart failure as it:
a) Reduced venous return
b) Increased afterload
c) Could worsen pulmonary edema
• Could not use higher pressures or frequencies

Negative Pressure Cuirass
Ventilators
Although cuirass negative pressure devices had
advantages over the tank in that they were easy to
use, were less cumbersome (whilst still covering the
chest and abdomen) and actually improved venous
return, there were severe disadvantages using this
method as:
• This method could not provide adequate tidal
volume or minute ventilation
• Could still not use higher pressures or frequencies
as still relied on passive recoil
• Therefore this method was by definition only an
augmenting type of ventilation

The Pneumobelt
The pneumobelt functions by exerting
pressure on the abdominal contents by
inflation of a rubber bladder, forcing the
diaphragm upward and assisting exhalation
(left). When the bladder deflates, gravity
pulls the diaphragm back down, assisting
inhalation (right).
Robert M. Kacmarek, “Home Mechanical Ventilation Equipment” in Respiratory Care Equipment
2nd Edition, Branson et al (New York: Lippincott, 1999)

The Rocking
Bed

Zidulka et al 1983 Am. R&V
CHEST WALL COMPRESSION
Expiratory active (Chest compression to below FRC)
Inspiratory passive (Chest recoil to almost FRC)

Bi-Phasic Cuirass
Ventilation (BCV)
„The Hayek Oscillator‟
(The H.O.)

Unification of Terms:
The method of ventilation of the H.O. and the RTX
which we are describing has been labelled in several
different ways:
Negative Pressure Ventilation (NPV)
External Chest Wall Oscillation (ECWO)
External High Frequency Oscillation (EHFO)
However, the most accurate and preferable
way to describe this method is:
Biphasic Cuirass Ventilation (BCV)

Negative Pressure Ventilation
+
+ BCV
Zidulka Chest Wall Compression + Pneumobelt

BCV (EHFO) AROUND ATMOSPHERIC PRESSURE WITH H.O.

EHFO AROUND NEGATIVE BASELINE

EHFO around negative baseline in a condition of reduced
FRC
By creating negative end expiratory chamber pressure, lung volume at
expiration is above initial FRC

12
An increase in Mean (MNCP) leads to an increase
in Lung Volume (VL)
Lung Volume (VL) ml/kg
10
8
6
4
2
0
-6 -10 -14
Mean Negative Chamber Pressure (MNCP) cmH2O

PaO2
250
An increase in Mean (MNCP) leads to an increase
in PaO2
200
150
100
50
0
-6 -10 -14
Mean Negative Chamber Pressure (MNCP) cm H2O

12
An increase in amplitude (span) leads to an
increase in tidal volume (Vt)
Vt (Tidal Volume) ml/kg
10
8
6
4
2
0
6 8 10 14
Span (cm H2O)

PaCO2
30
An increase in amplitude (span) leads to a
decrease in PaCO2
25
20
15
10
5
0
6 8 10 14
Span (cm H2O)

External High Frequency Oscillation Around Negative Baseline
- Preliminary Trials in Humans
Hayek Z., Schonfeld T.
Pediatric Intensive Care Unit, Beilinson Medical Centre, Sackler Faculty of Medicine,
Tel Aviv University, Israel
Ventilated five pediatric patients: (1) Heart failure and pneumonia (2)
Hypoventilation (3) Bronchiolitis Obliterans (COPD) (4) Bronchiolitis and
Pneumonia (5) Ataxia Telangectasia, Bronchiectasis and Restrictive
Pulmonary Disease
"This preliminary trial proved that patients with different lung
diseases can be ventilated effectively with External High
Frequency Oscillation around a Negative Baseline, while
completely avoiding intubation and positive pressure
ventilation."
Excerpta Medica 1990, pages 761-762, Proceedings of the 5 th World Congress on Intensive and Critical Care
Medicine, Kyoto, 3-8 September 1989

Acute Respiratory Failure (Paediatrics and
Adults)

Hayek Oscillator; Experience in Intensive Care
J.M. Campbell and M. Nevin
Bristol Royal Infirmary
In this study the HO has been used in two groups of patients in a general intensive care unit (ICU).
Group 1 - acute deceleration injury induced adult respiratory distress syndrome (ARDS) in patients who had
reached the criteria for extra-corporeal membrane oxygenation were commenced on the Hayek Oscillator, in
addition to their pressure control ventilation (PCV), with rapid improvement in their blood gases. "In all three cases
this resulted in a significant decrease in ICU time compared to controls."
In Group 2 - the Hayek Oscillator was introduced to either hasten weaning from IPPV or prevent ventilation. "In
four of the six patients this was successful with X-ray as well as clinical improvement and a reduction in ICU stay.“
Clinical Intensive Care Supplement to Volume 4, No. 2, 1993

The Combination of External High-Frequency Oscillation
and Pressure Support Ventilation
in Acute Respiratory Failure
S. Takeda, K. Nakanishi, T. Takano, J. Nejima, M. Takayama, G. Ishikawa 2 and R. Ogawa 1
Department of Intensive Care Medicine and 1 Anaesthesiology
Nippon Medical School, Tokyo, Japan
Results: Significant increases were noted in cardiac index (3.0 + 0.7 to 3.2 + 0.7 1 . min –1 . m
–2
, P

Chest Wall Oscillation in Acute Respiratory Failure Utilizing the Hayek Oscillator
M.R. Bennett, M.D., K.E. Blair, RRT, P.C. Fiehler, M.D., L.R. Kline, M.D.
Division of pulmonary Medicine, The Western Pennsylvania Hospital, Pittsburgh
"Nine consecutive patients in acute respiratory failure (ARF) were ventilated non-invasively using the Hayek
Oscillator. The frequencies used were confined to at or below the current FDA approved rates of 60 cycles/minute
(1 Hz). Three patients (33%) were complete responders, demonstrating a reduction in Pco 2
, an increase in
oxygenation and improved overall appearance. All members of this class avoided conventional mechanical
ventilation (CMV) and were the only patients in this study to survive the hospital stay. Three others were classified
as partial responders. The Hayek Oscillator allowed non-invasive stabilization of this group while deciding on
future care options. Three other patients in the non-responding group failed to tolerate the chest cuirass.
We conclude that the Hayek Oscillator, at frequencies up to 1
Hz, is capable of providing adequate ventilation in a subset of
patients in ARF, avoiding or delaying tracheal intubation.
This was accomplished in a manner that was non-invasive,
safe and comfortable."
American Review of Respiratory Disease International Conference Supplement, Volume 147, Number 4,
April 1993

External High Frequency Oscillation in Normal Subjects and in Patients with Acute
Respiratory Failure
Al-Saady NM, Fernando SS, Petros AJ, Cumin AR, Sidhu VS and Bennett ED
Department of Medicine, St. George's Hospital Medical School, London
External high Frequency oscillation was performed on 20 healthy volunteers using a cuirassbased
system, the Hayek Oscillator. Five-min periods of oscillation were carried out on each subject at
frequencies of !,2, 3, 4 and 5 Hz. Effective ventilation was measured in terms of the fall in alveolar partial
pressure of carbon dioxide immediately after oscillation. The optimum frequency for oscillation
was 1-3 Hz but most of the subjects were adequately ventilated over a wide range of frequencies. Thus, the
Hayek Oscillator is capable of adequately ventilating normal subjects by means of chest wall oscillation.
We also compared external high frequency oscillation with intermittent positive
pressure ventilation in five patients with respiratory failure. Using the same
inspired oxygen fraction, the external high frequency oscillation replaced
intermittent positive pressure ventilation for a 30-min period. External high
frequency oscillation improved oxygenation by 16% and reduced the arterial
carbon dioxide by 6%. These preliminary findings suggest that normal subjects
and intensive care unit patients can be adequately ventilated by means of external
high frequency oscillation.
Anaesthesia 50 (12): 103 -5, December 1995

Severe Tracheal Stenosis and Operative Delivery
Sutcliffe N, Remington SA, Ramsay TM, Mason C
Stepping Hill Hospital, Poplar Grove, Stockport, UK
We report the management of anaesthesia for Caesarean section in a
woman with severe extensive tracheal stenosis. Management was initially
with spinal anaesthesis, but general anaesthesis became necessary as a
result of profuse intra-operative bleeding. We describe the use of the
Hayek Oscillator cuirass ventilator to allow instrumentation of the larynx
whilst maintaining respiratory support, and for weaning from mechanical
ventilation.
Anaesthesia 50 (1): 26-9, January 1995

Chronic Lung Disease, COPD, Weaning and
Secretion Clearance

External High Frequency Ventilation in Severe Chronic Obstructive
Pulmonary Disease
S.A. Spitzer, M.D., F.C.C.P.; G. Fink, M.D.; and M. Mittelman, M.D.
Study Group: 20 patients with severe chronic obstructive pulmonary disease (COPD). 10
were eucapnic and 10 were hypercapnic. Frequencies from 60 to 140 cycles/min at an
amplitude of 36 cmH 2
O (-26 to +10).
The results show: "that the [Hayek Oscillator] is a powerful ventilator, reducing end-tidal Pco 2
(PetCO 2
) by 6.7 to
9.1 mm Hg in eucapnic patients and by 6.1 to 7.9 mm Hg in hypercapnic patients. The oxygen saturation
increased by 2 to 2.87 percent in the eucapnic patients and by 2.6 to 3.7 percent in the hypercapnic group in the
various frequencies. The rate of elimination of CO 2
and the levels of PetCO 2
achieved within a short time were
superior to those reported with other external ventilators.
We conclude that the [Hayek Oscillator] can be effectively used in severe COPD
and respiratory failure for (1) assisting ventilation, thus replacing intubation and
conventional mechanical ventilation, and (2) relieving muscle fatigue in short
sessions.
CHEST Vol. 104, p. 1698-1701, December 1993

Effects of External Chest Wall Oscillation in Stable COPD Patients
G.W. Soo Hoo, M.J. Ellison, C. Zhang, A.J. Williams, M.J. Belman,
Los Angeles VAMC and Cedars-Sinai Medical Center; UCLA School of Medicine,
Los Angeles, California
The effects of ECWO (using the Hayek Oscillator) were evaluated in four stable male patients with
severe COPD. They were studied during quiet breathing (control) and during ECWO at
frequencies of 30, 60 and 90 bpm. Best CO 2
elimination was at 90 bpm. They found that
"patients tolerated ECWO with reduction in ETCO 2
and maintenance of oxygenation despite smaller
VT.
This experience suggests that ECWO would be an acceptable and
effective alternative mode of non-invasive ventilatory support in COPD
patients."
American Journal of Respiratory and Critical Care Medicine Vol. 149, No. 4, April 1994

External High Frequency Ventilation for Weaning from Mechanical Ventilation
Gaitini MD*, Krimerman MD*, Smorgik MD**, Gruber MD**, Varzberger MD***
*Intensive Care Unit, Bnei Zion Hospital, Haifa, **Bikur Holim Hospital, Jerusalem;
***Meir Hospital, Kfar Saba, Israel
"We present three cases in which the Hayek Oscillator was used in weaning patients who became dependent on
C.M.V. and difficult to wean. Reventilation could be achieved within seconds, without the need for intubation and
without hazard to the patient. Therefore, using the Hayek Oscillator, arrest of ventilation was easily decided on. A
further advantage was a spontaneous mucus expulsion, each time the Hayek Oscillator was applied. External
ventilation allowed easy and early weaning. Hazards of reintubation [were] eliminated and the period of
ventilation and hospitalization reduced. The technique is noninvasive, well tolerated and costs less."
Recent Advances in Anaesthesia, Pain, Intensive Care and Emergency 5, 1990, Pages 137-138

High Frequency Oscillation as Adjuvant Pneumonia Therapy in Severe Head Injury
Dr. David Burns and Dr. Wayne Johnson
University of California, San Diego
"Pneumonia is a frequent, detrimental complication in severe head injury (SHI). Since chest physiotherapy (CPT)
is often poorly tolerated in SHI, we have investigated the utility of the Hayek High Frequency Chest Wall
Oscillation (CWO) in this setting. Vital signs remained stable during CWO, with no change in pulse, a mild (4
mmHg) increase in mean arterial pressure, and

Use in Surgery and Post-Surgery

The Hayek Oscillator: A New Method of Ventilation in Microlaryngeal
Surgery
Michael G. Dilkes, FRCS (Ed), FRCS et al.
ENT Department and the Department of Anaesthesia, Royal London Hospital,
London
Study Group: 25 patients, 25 to 75 years of age, all of whom required upper airway
endoscopy.
Conclusion: The "study has shown that the Hayek Oscillator appeared to provide
adequate ventilation in anesthetized, paralyzed patients without endotracheal
intubation, allowing us to perform unobstructed, unhurried microlaryngeal
surgery in all cases.
Annals of Otology & Laryngology June 1993, Volume 102, Number 6, pages 455-458

Use of the Hayek Oscillator in a Case of Failed Fibreoptic Intubation
Broomhead CJ, Dilkes MG, Monks PS
Department of Anaesthetics, Royal London Hospital Trust , Whitechapel, London
We describe the management of a patient with predicted difficult tracheal intubation after failed
awake fibreoptic intubation. Anaesthesia was induced with propofol and ventilation controlled by
means of the Hayek Oscillator, a high frequency cuirass ventilator, without tracheal intubation. The
patient underwent uneventful laser debulking of his massive pharyngeal tumour to establish a clear
airway.
British Journal of Anaesthesia Vol74(6): 720-1, June 1995

Anaesthesia for endescopic, laser, laryngeal and airway surgery using the
Hayek Oscillator and total intravenous anaesthesia
P.S. Monks and M.G. Dilkes
Minimally Invasive Therapy 1995: 4 (Suppl 2): 27-30
“Over 130 patients requiring laser surgery or endoscopic
laryngeal surgery have been ventilated using the Hayek
Oscillator”
“External High Frequency Oscillation around a negative
pressure baseline provides a satisfactory alternative to current
methods of ventilating patients undergoing endoscopic
laryngeal, or other airway surgery, e.g. tonsillectomy”

External High-Frequency Oscillation for Hypercapnia
after Upper Abdominal Surgery
Shinhiro Takeda 1 , Kazuhiro Nakanishi 1 , Teruo Takano 1 , Jun Nejima 1 , Morimasa Takayama 1 ,
Atsuhiro Sakamoto 2 and Ryo Ogawa 2
1
Division of Intensive Care and Coronary Care Unit and 2 Department of Anaesthesiology
Nippon Medical School, Tokyo, Japan
Seven patients were ventilated with EHFO for 2 hr at 60 oscillations/min, with cuirass
pressures of 36 cm H 2
O (-26 to +10), and an inspiratory to expiratory ratio of 1:1. Blood gases and
cardiac functional parameters were examined during the 2 hr on EHFO.
PaCO 2
significantly decreased from 61+8 mm Hg to 48+7 mm Hg after 10 min on
EHFO (p

The Use of the Hayek Oscillator to Produce Postoperative Hyperventilation
in the Neurosurgical Patient
Dr. A. Bristow FFARCS
Consultant Anaesthetist, St. Bartholomews Hospital, London
Twelve ASA I patients undergoing elective craniotomy were given a standardised anaesthetic.
Immediately after extubation at the end of the operation, the [Hayek] Oscillator was attached to the
patients.
There was a significant rise in PaO 2
and a significant reduction in PaCO 2
to the range 3.3 -4KPa. There were no signs of airway obstruction, and all
patients found the Oscillator comfortable.
Neuroanaesthetists Travelling Club of Great Britain and Ireland The Medical School,
Newcastle upon Tyne, Saturday 3 rd April, 1993

The Use of the Hayek Oscillator during Microlaryngeal Surgery
Monks PS, Broomhead CJ, Dilkes MG, McKelvie P
Nuffield Department of Anaesthetics, John Radcliffe Hospital, Headington,
Oxford, UK
An externally mounted cuirass ventilator, the Hayek Oscillator, was used on 41
patients undergoing surgery to the larynx without the use of tracheal tube. Gas
exchange and cardiovascular parameters remained satisfactory during the use
of this technique, which offers a significant advance over existing tubeless
methods of anaesthesia.
Anaesthesia 50(10): 865-9, October 1995

Effect on Cardiac Performance

The Effects of Positive and Negative Extrathoracic Pressure Ventilation
on Pulmonary Blood Flow
after the Total Cavopulmonary Shunt Procedure
D.J. Penny, Z. Hayek and A.N. Redington
Department of Paediatric Cardiology, Royal Brompton and National Heart
Hospital, London
"Pulmonary blood flow patterns were studied during the application of varying
extrathoracic pressure in 2 patients after total cavopulmonary anastomosis. The
application of negative extrathoracic pressure [by use of the Hayek
Oscillator] was associated with large increases in pulmonary
blood flow, while positive extrathoracic pressure caused
retrograde flow away from the lungs. These preliminary
observations suggest that negative extrathoracic pressure
may be useful as a means of respiratory support in patients
after right heart bypass procedures."
International Journal of Cardiology, 30 (1991) 128-130

Ventilation with External High Frequency Oscillation around a
Negative Baseline increases Pulmonary Blood Flow after the
Fontan Operation
D.J. Penny, Z. Hayek, P. Rawle, M.L. Rigby and A.N. Redington
Department of Paediatric Cardiology, Royal Brompton and National Heart Hospital, London
"When compared to that with intermittent positive pressure
ventilation, ventilation using external high frequency
oscillation increased pulmonary blood flow by
116+61.5%(p=0.013)."
"In summary, these data suggest that ventilation using a
cuirass device to provide a negative oscillatory pressure will
make a significant contribution to the post-operative care of
patients who require respiratory support after the Fontan
operation."
Cardiol Young 1992; 2:277-280

FONTAN OPERATION (Study 2)
Methods(1)
______________________________________________________________________
All studied under general anaesthesia and paralysis
Ventilated using intermittent positive pressure ventilation
Ventilated using a Hayek Oscillator
- negative pressure baseline (mean -8.5 mmHg)
End-tidal CO2 and arterial PO2 maintained constant

FONTAN OPERATION (Study 2)
Results
______________________________________________________________________
Oscillator/
IPPV (%)
P Value
Heart rate
Forward flow/cycle
Retrograde Flow/cycle
Nett forward/cycle
Nett forward/min
97%
198 + 68%
85 +17%
228 +85%
216 +65%
NS
0.022
NS
0.017
0.013

Negative-pressure Ventilation Improves Cardiac Output after Right Heart Surgery
L.S. Shekerdemian, D.F. Shore, C. Lincoln, A. Bush and A.N. Redington
Department of Paediatrics Royal Brompton Hospital, London, UK
"BACKGROUND: A low cardiac output state can complicate the postoperative course of patients undergoing
fontan-type operations and tetralogy of Fallot repair.
METHODS AND RESULTS: "We investigated the effect of negative-pressure ventilation on
cardiac output in 11 children in the early postoperative period after right heart surgery. All
patients were initially ventilated with volume-cycled intermittent positive-pressure ventilation, and negative
pressure ventilation was delivered with the Hayek external high-frequency oscillator.…. improved the
cardiac output by a mean of 46% (P=.005). Heart rate did not change, and
stroke volume increased by a mean of 48.5% (P=.005).
Mixed venous saturation increased by 4.6% (P

Cardiopulmonary Interactions after Fontan Operations
Augmentation of Cardiac Output Using Negative Pressure Ventilation
L.S. Shekerdemian, A. Bush, D.F. Shore, C. Lincoln, and A.N. Redington
Department of Paediatrics Royal Brompton Hospital, London, UK
METHODS AND RESULTS: "The hemodynamic effects of conversion from conventional intermittent positive
pressure ventilation (IPPV) to cuirass negative pressure ventilation (NPV) [Hayek Oscillator] was investigated
in nine acute postoperative Fontan patients on the pediatric intensive care unit and nine
anesthetized patents undergoing cardiac catheterization in the convalescent phase after
Fontan operations….. A brief period of NPV increased pulmonary blood flow from 2.4 to
3.5 L . min -1 . / m -2 with a mean increase of 42%. Pulmonary blood flow
continued to improve, with a total increase of 54% after an extended period
of NPV. Values fell toward baseline after reinstitution of IPPV. Heart rate was
unchanged during NPV and the improvement in pulmonary blood flow was achieved by an increase in stroke
volume from 25 mLm 2 to 37 mLm 2 .
CONCLUSIONS: Through improvement of the stroke volume alone, NPV
brought about a marked increase in the pulmonary blood flow and, hence,
cardiac output of Fontan patients. An improvement in cardiac output of
this order, and by this mechanism, is currently unmatched by any
therapeutic alternatives."
Circulation 1997:96: 3934-3942

Hemodynamic Effects of Different Modes of Mechanical Ventilation in Cardiac and Respiratory
Failure: An Experimental Study
G. Zobel*, D. Dacar** and S. Rodl*
Department of Pediatrics* and Cardiac Surgery**, University of Graz, Austria
Study was carried out on 12 pigs, to compare the hemodynamic effects of 4 different modes of Mechanical
Ventilation in 3 stable conditions: normal, acute ventricular failure by -blocking agents and respiratory failure
induced by repeated lung lavages. It was concluded that "ECG-triggered HFJV seems to have the best
benefits on cardiac output during control conditions, whereas EOSC [the Hayek Oscillator] seems to
have hemodynamic advantages in cardiac and respiratory failure conditions."
Clinical Intensive Care Supplement to Vol. 4 No. 2 1993

Improved Oxygen Delivery by Positive Pressure
Ventilation with Continuous Negative External Chest
Pressure.
Scholz S.E., Knothe C., Thiel A. and Hempelmann G.
Higher positive end-expiratory pressures (PEEP) improve arterial pO2 by raising the tidal
range above closing capacity, while decreasing cardiac output.
5 critically ill patients on positive pressure ventilation with pre-existing PEEP exceeding 10 cm
H2O were recruited into a two period cross-over trial. The effects of 4h of positive pressure
ventilation with PEEP (CPPV-PEEP) were compared with positive pressure ventilation with
continuous negative external chest pressure (CPPV-CNECP).
The switch from (CPPV-PEEP) to (CPPV-CNECP) decreased mean airway pressure (19.9 vs
14.3 cm H2O.
Compared with CPPV-PEEP, the combination of positive-pressure ventilation
with negative external chest pressure led to an increase in oxygen delivery
because of an enhancement in cardiac index (mean 4.55 vs 6.40 L/min)
The Lancet Saturday 3 May, 1997, Vol.349 No. 9061: 1295–1296

Ventilation by external high-frequency oscillations improves cardiac function after
coronary artery bypass grafting
B. Sideno, J. Vaage ,
Department of Thoracic Surgery, Karolinska Hospital, Stockholm, Sweden
Objective: To compare the effects of ventilation with intermittent positive pressure and external high frequency
oscillation by the Hayek Oscillator during the first 5 h after coronary artery bypass grafting.
Methods: Eleven patients were randomized to intermittent positive pressure ventilation throughout the
observation period (5 h), while 13 patients were initially ventilated with intermittent positive pressure ventilation,
then by external high-frequency oscillations for 4 h. changing to positive pressure ventilation for the last hour.
Results: Cardiac index, stroke volume index, right ventricular stroke work index,
right ventricular end-diastolic volume index and mixed venous oxygen saturation
were significantly increased during ventilation with external high-frequency
oscillations, and arteriovenous oxygen content difference was significantly
reduced.
Conclusions: "Ventilation by external high-frequency oscillations increases cardiac index and improves tissue
perfusion….The Hayek Oscillator may have distinct cardiovascular benefits as ventilatory assistance in
postoperative cardiac surgical patients."
European Journal of Cardio-thoracic Surgery 11 (1997) 248-257

L * min -1 m2
Cardiac Index
EHFO
IPPV
3
2
1
0
1 2 3 4 5 6 7
Time (Hours)

Biphasic Extrathoracic Pressure CPR
A Human Pilot Study
Howard A. Smithline et al.
Department of Emergency Medicine, Henry Ford Health Systems, Henry
Ford Hospital, Detroit
"Biphasic Extrathoracic Pressure CPR [using the Hayek Oscillator] significantly
increases the coronary perfusion pressure when compared with standard CPR
[a pneumatic compression device (the Thumper)]. Additionally, there is a trend
for improved systemic perfusion as indicated by the improved venous to arterial
Pco 2
gradient, although this is not reflected by significant decreases in the
OER. Oxygenation and ventilation appear to be adequately maintained, thus
obviating the need for positive pressure ventilation with its associated risks."
CHEST Vol. 105, p. 842-846, March 1994.

Bi-Phasic Cuirass
Ventilation (BCV)
„The RTX Respirator‟

BCV Summary
-Biphasic Cuirass Ventilation (BCV) is often the ideal
ventilator as it:
a) Provides complete ventilation to patient
b) Is non-invasive
c) Works in a physiological way, in that it:
i) Works in the way that the lungs work most efficiently by
actively controlling both phases of the respiratory cycle
ii) Provides even ventilation for patient
iii) Helps to maintain and redevelop the respiratory muscles
which often wither and waste with respiratory failure and
mechanical ventilation
iv) Improves cardiac output

BCV Summary
-Biphasic Cuirass Ventilation (BCV) is often the ideal
ventilator as it:
d) Provides an efficient method of weaning from PPV
e) Assists patient to remove secretions which are a symptom
of most respiratory diseases, aggravating the condition of
these patients
f) Can begin to provide treatment for patients before their
condition deteriorates and hospitalisation is required
g) Allows for continuity of treatment for patients in hospital,
at home, in transport and in emergency situations
h) Is simple to use and comfortable for the patient

Coronary MRA with synchronised
respiratory and cardiac motion using an
external respirator reduces scan times and
improves navigator efficiency
S. Plein, T.N. Bloomer, J.P. Ridgway, T. Jones,
Z. Hayek * , U.M. Sivananthan
C A R D I A C
L E E D S
L E E D S
M R
Cardiac MRI Unit
BHF Heart Research Centre
Leeds General Infirmary, UK
* Medivent Ltd. London, UK

Respiratory synchronisation
• Modified RTX respirator* (Medivent, London, UK)
• External respirator – no preparation required
• Plastic cuirass, airtight seal, drive unit
• Respiratory phases actively controlled by
pressure change inside the cuirass:
­ pressure: chest compression: expiration
­ pressure: chest expansion: inspiration
• Highly reproducible chest + diaphragm positions
• ECG triggered mode: 1 full respiratory cycle per
cardiac cycle.
* S. Plein et al. Synchronising cardiac and respiratory motion with an external cuirass respirator.
Poster 1834, ISMRM 2001

Tube
Velcro straps
Cuirass
Foam seal
Pressure transducer

BCV - Advantages
• No requirement for sedation
• No risk of VAP
• No risk of barotrauma
• Increased patient comfort
• Increase in cardiac output
• Can be used in place of NI Mask, helmet etc
• In most cases a direct replacement for IPPV
• Management of secretions
• Provides Physiotherapy and cough assistance
• Decreased stay in ICU post operative

BCV Disadvantages
• Can not be used on patients over 170kg
• Requires a patent/viable airway
• Can not be used on burns patients
• Can not be used during surgery

Thank you
• BCV – Available from Cheiron a.s.