Table 2 Average ventilation, blood gases, blood lactate concentration, heart rate and perceived level of exertion during the 15-min hyperpnoea test in normoxia, hypoxia and hyperoxia
From: Effect of acute hypoxia on respiratory muscle fatigue in healthy humans
| Â | Normoxia | Hypoxia | Hyperoxia |
|---|---|---|---|
| 159.3 (15.6) | 158.1 (15.6) | 159.5 (15.1) |
fR (cycles·min-1) | 54.2 (4.3) | 54.2 (4.9) | 53.7 (4.1) |
VT (l) | 2.95 (0.26) | 2.93 (0.30) | 2.98 (0.25) |
Ti/Tt | 0.48 (0.03) | 0.49 (0.03) | 0.49 (0.04) |
PET CO2 (mmHg) | 37.0 (2.1) | 36.8 (1.7) | 35.9 (2.3) |
SpO2 (%) | 98.4 (0.9) | 79.3 (1.9) *** | 98.9 (0.7) |
PaO2 (mmHg) (n = 6) | 123.7 (1.8) | 46.0 (0.8) *** | 347.9 (29.0) ### |
PaCO2 (mmHg) (n = 6) | 37.1 (1.2) | 36.7 (1.1) | 37.5 (0.8) |
pH (n = 6) | 7.42 (0.02) | 7.42 (0.01) | 7.40 (0.03) |
[La] (mmol·l-1) (n = 6) | 1.6 (0.4) | 2.1 (0.7) + | 1.3 (0.3) |
HR (bpm) | 98 (23) | 99 (23) + | 86 (16) |
RPE (points) | 6.0 (0.9) | 5.8 (1.2) | 5.2 (0.6) |
(l min-1)- Values are means (SD).
, minute ventilation; fR , breathing frequency; VT , tidal volume; Ti/Tt, ratio of inspiratory time to total respiratory cycle duration; PET CO2 , end-tidal CO2 partial pressure; SpO2 , arterial O2 saturation; PaO2 , arterial oxygen partial pressure; PaCO2 , arterial carbon dioxide partial pressure; [La], blood lactate concentration; HR, heart rate; RPE, rate of perceived exertion. *** significantly different from normoxia and hyperoxia (P < 0.001), ### significantly different from normoxia and hypoxia (P < 0.001), + significantly different from hyperoxia (P < 0.05)