The effects of oxygen in patients with sleep apnea

The effects of 6 h of continuous low flow, nasally administered oxygen were compared with the effects of breathing air in 10 men and 2 women with obstructive sleep apnea and daytime hypersomnolence. The overall quality of sleep, sleep fragmentation, the pattern of breathing, nocturnal oxygenation, and the clinical effects on daytime hypersomnolence determined by multiple sleep latency testing were evaluated. We found that in non-REM sleep, breathing 3 L/min of oxygen increased baseline percent arterial oxyhemoglobin saturation and decreased both the rate of sleep-disordered breathing from 69 ± 36 to 56 ± 39 (mean ± SD) (p < 0.02) episodes per hour and the peak fall in arterial oxyhemoglobin saturation from 11.5 ± 5.6% to 6.5 ± 4.0% (p < 0.001). In addition, oxygen significantly reduced the percentage of central and mixed sleep-disordered breathing events, thus increasing the percentage of obstructive sleep-disordered breathing events. In contrast, during REM sleep, neither the baseline nor the peak fall in oxyhemoglobin saturation during disordered breathing improved; however, there was a significant reduction in hourly sleep-disordered breathing rate from 70 ± 17 to 56 ± 23 (p < 0.02) episodes. These improvements in oxygenation and pattern of breathing were associated with improved sleep architecture characterized by a decrease in the number of awakening from sleep and an increased total sleep time from 335 ± 72 to 369 ± 68 min (p < 0.05). Although 7 of 12 patients felt more alert after oxygen therapy, there was no overall improvement in multiple sleep latency test results. We conclude that low flox oxygen consistently improved physiologic sleep parameters in all patients and may be useful clinically in selected patients with sleep-disordered breathing.