Fig. 3.

The effect of supplemental oxygen on breathing. Supplemental oxygen effectively reduced the number of central apneas and periodic breathing. Base, baseline PSG results on room air; CAI, central apnea index; EtCO₂ P₉₅; 95th percentile level of EtCO₂ during sleep; nPB, periods without periodic breathing in nREM; nREM, non-rapid-eye movement sleep; O₂, PSG results on supplemental oxygen; OAHI, obstructive apnea and hypopnea index; ODI_≥3, pulse oximeter oxyhemoglobin desaturation of 3% or more; PB, periodic breathing episodes in non-REM sleep; SpO₂, pulse oximeter oxyhemoglobin saturation; SpO₂ P₅, 5th percentile level of SpO₂ during sleep.