CONTINUOUS POSITIVE AIRWAY PRESSURE (CPAP) IS CONSIDERED TO BE THE MOST EFFECTIVE AND THE PREFERRED THERAPY FOR OBSTRUCTIVE SLEEP apnea

CONTINUOUS POSITIVE AIRWAY PRESSURE (CPAP) IS CONSIDERED TO BE THE MOST EFFECTIVE AND THE PREFERRED THERAPY FOR OBSTRUCTIVE SLEEP apnea (OSA). In placebo-controlled and uncontrolled studies, CPAP has been shown to correct the elevated apnea-hypopnea index (AHI) and the transient desaturations associated with respiratory events during sleep.1-4 In uncontrolled studies, CPAP has also been shown to improve daytime sleepiness,5,6 mood,7 cognitive function,8 quality of life,9 and cardiovascular function in patients with OSA.10 In 1 controlled study of subtherapeutic CPAP, CPAP was effective in reducing excessive daytime somnolence and improving self-reported well-being.11 However, the effects of CPAP in improving sleep quality in OSA have been less consistent.1,12 Patients with OS generally have poor sleep quality, characterized by short sleep latency, increased stage 1 sleep, decreased rapid eye movement (REM) sleep and slow-wave sleep (SWS), poor sleep efficiency, and frequent sleep fragmentation caused by transient arousals. We were surprised to find that only 2 randomized placebo-controlled trials have evaluated the effectiveness of CPAP in improving sleep quality. We previously reported that, in patients with severe OSA , a 1-week trial of CPAP was not different from placebo-CPAP (CPAP at a subtherapeutic pressure) in improving sleep architecture, except for improvement in arousal index.1 More recently, McArdle and Douglas reported improvements in stage 1 sleep, SWS, and the arousal index after 4 weeks on CPAP but no improvement in REM sleep in a randomized cross-over study utilizing an oral capsule as placebo.12 In 1997, in a systematic review of the sleep literature, the effectiveness of CPAP as a treatment for OSA was called into question because of the dearth of studies using adequate placeboCPAP controls.13 This review highlights the need for rigorously controlled studies, which are still all too few in the field of sleep medicine. We therefore designed a study to further evaluate the effects of CPAP on sleep quality in patients with OSA, comparing it with a placebo-CPAP that delivered virtually no CPAP pressure. The effect of supplemental oxygen on sleep architecture in patients with OSA has not been rigorously studied against CPAP or placebo-CPAP controls. In some patients with OSA who cannot tolerate CPAP and are not candidates for a surgical procedure, supplemental oxygen therapy has been used in an attempt to reverse the harmful effects of the transient hypoxemia during sleep.14,15 Nocturnal supplemental oxygen has been suggested by some as an alternative therapy in the patient with OSA who is not somnolent or not compliant with CPAP.15,16 Most studies evaluating supplemental oxygen in OSA have included only a few patients, had mixed results, and used nasal cannulas to deliver oxygen, and few have evaluated the effect of supplemental oxygen on sleep architecture in OSA.15-18 To our knowledge, the combination of placebo-CPAP with oxygen, to allow for a more-precise and needed comparison with CPAP therapy, has not been reported. The aim of this study was to evaluate the effectiveness of CPAP or supplemental oxygen, delivered via placebo-CPAP set-up, on sleep quality in patients with OSA in a randomized double-blind placebo-CPAP–controlled trial after 1 day and after 2 weeks of treatment. Effect of Continuous Positive Airway Pressure Versus Supplemental Oxygen on Sleep Quality in Obstructive Sleep Apnea: A Placebo-CPAP–Controlled Study