Normal Respiratory Values

AIn: Equine Respiratory Diseases, Lekeux P. (Ed.). International Veterinary
Information Service, Ithaca NY (www.ivis.org), 22-Apr-2005; B0341.0405
Normal Respiratory Values
E. Van Erck, T. Art and P. Lekeux
Department of Physiology and Sport Medicine, Faculty of Veterinary Medicine,
University of Liège, Liège, Belgium.
Conversion Table for Common Values
Data SI Units* Other Units
Pressure 1 kPa 7.5 mmHg
1 kPa 10.2 cmH2O
1 kPa 10 mbar
1 kPa 0.0099 atm
1 kPa 0.1 N/cm 2
Work 1 J 0.239 cal
1 J 10.2 cmH2O.cm 2
Power 1 W 0.0143 kcal/min
Gas exchange 1 mmol/min 22.4 ml/min
Gas content 1 mmol/liter 2.24 ml/dl
Hemoglobin 1 mmol/liter 16.1 g/liter
*SI Units = International System of Units.
Other conversion tables are available at:
www.digitaldutch.com/unitconverter
www.onlineconversion.com
www.megaconverter.com/mega2
1. Normal Ventilation Values
1.1. Normal Ventilation Values in Adult Horses
Mean ventilation values in healthy Thoroughbred horses considered average for their
quality, fitness, age (5 years), and size (mean body weight 470 kg) and running on a
treadmill under temperature climatic conditions (lung and gas volumes are expressed as
BTPS and STPD respectively). Measurements were made at 6 m/s at walk (duration: 5
minutes), 3.4 m/s at trot (duration: 5 minutes), 8 m/s at canter (duration: 1 minute) and
10 m/s with 4% slope incline at gallop (duration: 1 minute) and 5 minutes after recovery
[1].
Value Unit Rest Walk
Slow
Trot
Canter Fast Gallop Recovery

Value Unit Rest Walk
Slow
Trot
Canter Fast Gallop Recovery
VO2max% % 3.3 14 18 60 100 20
VT liters 5.6 5.8 6.2 9.2 13.2 6.5
VD liters 3.4 3.4 3.5 2.6 2.6 3.5
VA liters 2.2 2.4 2.8 6.6 10.6 3.0
VD/VT % 60 58 57 28 20 54
f breaths/min 14 65 91 113 121 110
ti seconds 1.9 0.45 0.34 0.27 0.25 0.29
te seconds 2.4 0.47 0.32 0.27 0.25 0.26
ti/ttot % 44 49 52 50 50 53
E
D
A
E/VO2
E/VCO2
mean i
mean e
imax
emax
i
e
liters/min 78 377 564 1040 1598 715
liters/min 47 219 321 291 320 386
liters/min 31 158 243 749 1278 329
liters/liter 35 40 47 26 24 55
liters/liter 43 48 51 27 23 51
liters/s 2.9 13 19 34 53 26
liters/s 2.3 12 20 34 53 30
liters/s 4.1 14 27 45 64 32
liters/s 4.2 18 30 52 79 39
liters/s 2
liters/s 2
8 240 632 1124 1685 650
7 225 566 1086 1595 744
VO2max %: percent of maximal oxygen uptake; VT: tidal volume; VD: physiological dead space; VA:
alveolar volume; VD/VT: ratio of dead space to tidal volume; f: breathing frequency; ti: inspiratory
time of the breathing cycle; te: expiratory time; ti/ttot: ratio of inspiratory to total time of the
breathing cycle; E: minute volume; D: dead space ventilation; A: alveolar
ventilation; E/VO2: ventilatory equivalent for oxygen uptake; E/VCO2: ventilatory
equivalent for carbon dioxide output; mean i: mean inspiratory flow or inspiratory drive; mean
e: mean expiratory flow; imax: peak inspiratory flow; emax: peak expiratory flow;
i: volume acceleration at the onset of inspiration; e: volume acceleration at the onset of

Value Unit Rest Walk
expiration.
1.2. Normal Ventilation in Neonate Foals
Slow
Trot
Canter Fast Gallop Recovery
Ventilatory parameters and pressure changes during normal tidal breathing in the standing
foal less than 1 week of age [2,3]
Age in
Days
n VT (L)
2 7
0.65 ±
0.15
7 9
0.90 ±
0.17
Values are means ± s.d.
VT/kg
(ml/kg)
15.8 ± 2.5
17.6 ±3.0
f (bpm) E
E/kg
(L/min) (ml/kg)
53.9 ±
9.9
34.8 ± 12.0 848 ± 231
40.9 ±
5.2
33.9 ± 7.5 717 ± 157
Ti (sec) Te (sec)
0.51 ±
0.15
0.65 ±
0.10
0.72 ±
0.09
0.75 ±
0.17
VT: tidal volume; f: frequency of breathing, bpm: breaths per minute; E: minute ventilation; Ti:
inspiratory time; Te: expiratory time.
2. Normal Values of Breathing Mechanics
2.1. Normal Values of Breathing Mechanics in Adult Horses
Mean ventilation values in healthy Thoroughbred horses considered average for their
quality, fitness, age (5 years), and size (mean body weight 470 kg) and running on a
treadmill under temperature climatic conditions (lung and gas volumes are expressed as
BTPS and STPD respectively). Measurements were made at 6 m/s at walk (duration: 5
minutes), 3.4 m/s at trot (duration: 5 minutes), 8 m/s at canter (duration: 1 minute) and
10 m/s with 4% slope incline at gallop (duration: 1 minute) and 5 minutes after recovery
[1].
Value Unit Rest Walk Slow Trot Canter Fast Gallop Recover 5'
Ppl min kPa -0.78 -1.19 -1.78 -3.19 -4.85 -1.68
Ppl max kPa -0.34 0.31 0.55 2.42 3.62 0.53
MaxΔPpl kPa 0.44 1.50 2.33 5.61 8.47 2.21
Pin kPa 0.02 0.54 1.16 2.61 4.26 1.71
ΔPV = 0 kPa 0.24 -0.29 -0.90 -2.42 -3.88 -1.90
Cdyn liter/kPa 23 -20 -6.8 -3.8 -3.4 -3.4
RL Pa/liter/s 25 26 30 48 57 27
RUA Pa/liter/s 20 21 23 38 46 21
RLA Pa/liter/s 5 5 7 10 11 6
Wvis J 1.4 6.2 14 36 82 14
vis
J/min 17 403 1274 4068 9922 1540

Value Unit Rest Walk Slow Trot Canter Fast Gallop Recover 5'
vis/VE
vis/VO2
J/min 0.22 1.07 2.2 3.9 6.2 2.2
J/liter 7.7 42 106 102 148 118
Ppl min: peak intrapleural pressure recorded during inspiration; Ppl max: peak intrapleural pressure
recorded during expiration; maxΔPpl: maximum change in intrapleural pressure; Pin: initial pressure;
ΔPV=0: intrapleural pressure gradient between the 2 points of zero flow; Cdyn: dynamic lung
compliance; RL: total pulmonary resistance; RUA: upper airways resistance; RLA: lower airways
resistance; vis: viscous work of breathing; vis: minute work of breathing; vis/VE:
work of breathing per ventilated liter; vis/VO2: work of breathing per liter of oxygen uptake.
2.2. Normal Values of Impulse Oscillometry Mechanics in Adult Horses
Values of respiratory resistance (Rrs) measured from 5 to 35 Hz with
the Impulse Oscillometry System (IOS) [4]
Rrs (kPa/l/s) Mean SD CLL CLU
R5Hz 0.070 0.012 0.066 0.074
R10Hz 0.081 0.011 0.077 0.085
R15Hz 0.088 0.012 0.085 0.092
R20Hz 0.079 0.010 0.076 0.083
R25Hz 0.075 0.010 0.072 0.078
R35Hz 0.062 0.009 0.059 0.065
SD: Standard deviation, CLL: 95% lower confidence limit, CLU: 95% upper
confidence limit
Values of reactance (Xrs) measured from 5 to 35 Hz with the Impulse
Oscillometry System (IOS) [4]
Xrs (kPa/l/s) Mean SD CLL CLU
X5Hz 0.020 0.007 0.017 0.022
X10Hz 0.015 0.009 0.012 0.018
X15Hz 0.009 0.012 0.005 0.013
X20Hz 0.006 0.015 0.001 0.010
X25Hz 0.003 0.013 -0.001 0.008
X35Hz -0.003 0.010 -0.007 0.000
SD: Standard deviation, CLL: 95% lower confidence limit, CLU: 95% upper
confidence limit
3. Normal Gas Exchange Values
3.1. Normal Values of Blood Gases in Adult Horses

PaO2 85 - 105 mmHg
PaCO2 42 - 46 mmHg
pH 7.38 - 7.42
Mean ventilation values in healthy Thoroughbred horses considered average for their
quality, fitness, age (5 years), and size (mean body weight 470 kg) and running on a
treadmill under temperature climatic conditions (lung and gas volumes are expressed as
BTPS and STPD respectively). Measurements were made at 6 m/s at walk (duration: 5
minutes), 3.4 m/s at trot (duration: 5 minutes), 8 m/s at canter (duration: 1 minute) and
10 m/s with 4% slope incline at gallop (duration: 1 minute) and 5 minutes after recovery
[1].
Value Unit Rest Walk Slow Trot Canter Fast Gallop Recover 5'
O2
ml/kg/min 4.7 20.2 25.5 85.1 142.5 27.7
CO2
ml/kg/min 3.8 17.0 23.4 80.9 146.8 29.8
R - 0.82 0.85 0.92 0.95 1.03 1.07
Venous PO2 mmHg 39 32 30 25 16 62
Venous PCO2 mmHg 47 49 50 64 96 43
HCO3 -
mmol/liter 28.8 28.9 27.5 26.6 23.0 19.2
Arterial PO2 mmHg 95 101 99 83 69 115
Arterial PCO2 mmHg 45 44 43 46 50 32
(A-a) ΔO2 mmHg 4 2 4 16 29 6
pHa - 7.39 7.40 7.40 7.39 7.26 7.36
PCV % 38 42 44 48 58 56
Hb G/liter 140 150 160 175 220 220
Arterial SO2 % 97 97.5 97 95 90 98.5
Arterial CO2 liter% 20 22 22 25 28 33
Venous CO2 liter% 14 11 11 7 5 21
C(a-v)O2 liter% 6 11 11 18 23 12
Alveolar PO2 mmHg 99 103 103 99 98 121
Alveolar PCO2 mmHg 44 43 42 45 49 31
FmeO2 % 16.2 17.0 17.7 14.9 14.3 18.4
FmeCO2 % 2.6 2.6 2.5 4.6 5.4 2.1
FetO2 % 14.0 14.5 14.5 13.9 13.9 17.2
FetCO2 % 6.3 6.1 6.0 6.4 7.0 4.5
O2: oxygen uptake; CO2: carbon dioxide output; R: respiratory exchange ratio; venous
PO2: venous oxygen partial pressure; venous PCO2: venous carbon dioxide partial pressure; arterial
PO2: arterial oxygen partial pressure; arterial PCO2: arterial carbon dioxide partial pressure; HCO3 - :
bicarbonate content; [A-a] ΔO2: alveolar-arterial oxygen gradient; pHa: arterial pH; PCV: packed
cell volume; Hb: blood hemoglobin concentration; arterial SO2: percent saturation of hemoglobin
with oxygen; arterial CO2: arterial oxygen content; venous CO2: venous oxygen content; C(a-v)O2:
arteriovenous oxygen content gradient; alveolar PO2: alveolar oxygen partial pressure; alveolar

PCO2: alveolar carbon dioxide partial pressure; FmeO2: mixed expired oxygen fraction; FmeCO2:
mixed expired carbon dioxide fraction; FetO2: end-tidal oxygen fraction; FetCO2: end-tidal carbon
dioxide fraction.
3.2. Normal Values of Arterial Blood Gases in Foals
Gestational
Age/Status
Values measured from birth until 1 week (expressed as mean ± SEM)
Postnatal
Age
Normal 3 - 168 hr Lateral
Normal
1 - 12 hr
12 - 48 hr
48 - 168 hr
Position pH
Lateral
Normal 4 - 11 hr Lateral
Normal
24 hr
24 hr
48 hr
48 hr
72 hr
72 hr
144 hr
144 hr
Standing
Lateral
Standing
Lateral
Standing
Lateral
Standing
Lateral
Premature 0.5 - 11 hr Lateral
Term
Birth
2 min
15 min
30 min
60 min
2 hr
4 hr
12 hr
24 hr
48 hr
96 hr
Lateral
Lateral
Lateral
Lateral
Lateral
Lateral
Lateral
Lateral
Lateral
Lateral
Lateral
7.354 ±
0.011
7.378 ±
0.015
3.374 ±
0.004
7.384 ±
0.014
7.367 ±
0.10
7.41 ± 0.03
7.38 ± 0.05
7.40 ± 0.03
7.37 ± 0.00
7.39 ± 0.07
7.44 ± 0.14
7.42 ± 0.03
7.41 ± 0.03
7.208 ±
0.48
7.413 ±
0.019
7.312 ±
0.016
7.322 ±
0.025
7.354 ±
0.010
7.362 ±
0.013
7.362 ±
0.012
7.355 ±
0.017
7.357 ±
0.024
7.393 ±
0.012
PaCO2
mmHg
PaO2
mmHg HCO3 n Ref
47.5 ± 2.6 80.0 ± 3.8 10 [5]
42.2 ± 1.8
44.5 ± 1.2
42.4 ± 1.0
77.3 ± 3.1
83.2 ± 3.1
88.2 ± 5.9
6
6
5
[6]
39.5 ± 1.8 83.8 ± 6.3 5 [7]
45.2 ± 2.5
48.1 ± 3.8
47.5 ± 3.7
49.5 ± 2.8
49.6 ± 1.5
51.6 ± 7.2
47.3 ± 2.3
46.9 ± 2.1
84.6 ± 6.9
72.69 ±
14.2
106.6 ± 3.9
89.6 ± 12.7
104.5 ± 4.8
94.1 ± 4.3
98.8 ± 4.8
84.2 ± 6.9
3
3
3
3
5
5
5
5
[8]
55.3 ± 3.6 53.7 ± 1.5 7 [6]
45.7 ± 1.1
54.1 ± 2.0
50.4 ± 2.7
51.5 ± 1.5
47.3 ± 2.2
47.7 ± 1.7
45.0 ± 1.9
44.3 ± 1.2
45.5 ± 1.5
46.1 ± 1.1
45.8 ± 1.1
39.7 ± 2.1
56.4 ± 2.3
57.5 ± 3.6
57.0 ± 1.8
60.9 ± 2.7
66.5 ± 2.3
75.7 ± 4.9
73.5 ± 3.0
67.6 ± 4.4
74.9 ± 3.3
81.2 ± 3.1
26.3 ±
1.1
24.0 ±
1.2
24.4 ±
1.6
25.3 ±
0.7
25.3 ±
1.0
25.0 ±
0.9
23.6 ±
1.1
23.2 ±
1.3
26.2 ±
1.1
8
10
9
10
9
8
10
10
9
8
8
[9]

Gestational
Age/Status
Values measured from birth until 1 week (expressed as mean ± SEM)
Postnatal
Age
4. Pulmonary Hemodynamics
Position pH
7.398 ±
0.008
7.396 ±
0.012
PaCO2
mmHg
PaO2
mmHg HCO3
25.7 ±
0.6
23.2 ±
2.1
n Ref
Mean ventilation values in healthy Thoroughbred horses considered average for their
quality, fitness, age (5 years), and size (mean body weight 470 kg) and running on a
treadmill under temperature climatic conditions (lung and gas volumes are expressed as
BTPS and STPD respectively). Measurements were made at 6 m/s at walk (duration: 5
minutes), 3.4 m/s at trot (duration: 5 minutes), 8 m/s at canter (duration: 1 minute) and
10 m/s with 4% slope incline at gallop (duration: 1 minute) and 5 minutes after recovery
[1].
Value Unit Rest Walk
Slow
Trot
Canter Fast Gallop Recover 5'
HR beats/min 35 75 103 155 210 83
SV liters 1.05 1.07 1.12 1.39 1.36 1.32
Q liters/min 37 80 115 215 285 110
PaPmax mmHg 37 69 78 99 152 53
PaPmin mmHg 22 30 39 47 50 26
PaPm mmHg 28 43 52 65 82 35
Pw mmHg 16 25 30 37 49 20
P (aP-w) mmHg 12 18 22 28 33 15
PVR mmHg/liter/min 0.32 0.22 0.19 0.13 0.11 0.14
T°a °C 37.5 37.9 38.1 38.7 41.3 39.7
O2/HR
ml/kg/beat 0.06 0.25 0.25 0.55 0.68 0.34
liters/liter 0.84 1.98 2.11 3.48 4.48 3.00
A/Q
HR: heart rate; SV: stroke volume; Q: cardiac output; PaPmax: maximal pulmonary artery pressure;
PaPmin: minimal pulmonary artery pressure; PaPm: mean pulmonary artery pressure; Pw:
pulmonary artery wedge pressure; P(aP-w): pulmonary driving pressure; PVR: pulmonary vascular
resistance; T°a: arterial blood temperature; O2/HR: oxygen pulse; A/Q: global
ventilation/perfusion ratio.
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Click on the author's name to view a list of his/her publications: E. Van Erck, T. Art and
P. Lekeux