Table 1.

Baseline and pre-hypopnoea/apnoeic respiration

	Room air			Hypoxia
	Baseline	Pre-hypopnoea	Pre-apnoea	Baseline	Pre-hypopnoea	Pre-apnoea
VT (ml)	351 ± 15	479 ± 52†	614 ± 63†‡	376 ± 24	402 ± 24†	514 ± 64†‡
f (breaths min−1)	16 ± 1	14 ± 1†	12 ± 1†‡	17 ± 1*	17 ± 1*†	16 ± 1*†‡
${\stackrel{\mathrm{.}}{V}}_{\mathrm{E}}$ (l min−1)	5.4 ± 0.3	6.4 ± 0.6†	7.1 ± 0.5†	6.3 ± 0.4*	6.5 ± 0.4†	7.5 ± 0.6†
PET,CO2 (mmHg)	45.0 ± 1.1	43.0 ± 1.2†	41.6 ± 1.0†‡	42.4 ± 1.3*	42.1 ± 1.4	41.3 ± 1.2†‡
PET,O2 (mmHg)	103 ± 3	108 ± 3	113 ± 3†‡	54 ± 2*	59 ± 2*	64 ± 2*†‡

^*P < 0.05, hypoxia vs. room air

^†P < 0.05, compared to the baseline value

^‡P < 0.05, compared to hypopnoea. V_T, tidal volume; ${\stackrel{\mathrm{.}}{V}}_{\mathrm{E}}$, minute ventilation; P_ET,CO2, end-tidal partial pressure of CO₂; P_ET,O2, end-tidal partial pressure of O₂.