Table 3.
A comparison of the mean ± s.e.m.chemoreflex characteristics (all volunteers and all days), measured using hypoxic and hyperoxic rebreathing tests, before and after exposure to 20 min isocapnic (eucapnic) hypoxia
| Before | After | |||
|---|---|---|---|---|
| Hypoxic | Hyperoxic | Hypoxic | Hyperoxic | |
| Threshold for CO2 | ||||
| Ventilation (mmHg) | 40±0.4 | 45±0.5 | 42±0.5* | 44±0.4 |
| Tidal volume (mmHg) | 39±0.4 | 44±0.4 | 41±0.5* | 44±0.4 |
| Frequency (mmHg) | 42±0.6 | 46±0.8 | 43±0.5* | 46±0.6 |
| Sensitivities to CO2 | ||||
| Ventilation (l min−1 mmHg−1) | 8.1±0.8 | 6.9±0.68 | 8.8±0.82 | 7.0±0.79 |
| Tidal volume (ml min−1 mmHg−1) | 266±29 | 241±25 | 304±29 | 252±29 |
| Frequency (breaths min−1 mmHg−1) | 3.9±0.5 | 2.9±0.3 | 3.4±0.4 | 2.5±0.3 |
| Basal (subthreshold) | ||||
| Ventilation (l min−1) | 8.0±0.8 | 7.0±0.5 | 7.1±0.7 | 6.4±0.6 |
| Tidal volume (ml) | 591±52 | 578±46 | 468±53 | 483±53 |
| Frequency (breaths min−1) | 12.2±0.7 | 10.8±0.8 | 11.3±0.8 | 12.6±0.9 |
*
Significantly different values.