Polysomnography and maintenance of wakefulness test as predictors of CPAP effectiveness in obstructive sleep apnea

Nasal continuous positive airway pressure (CPAP) therapy is usually effective in the treatment of obstructive sleep apnea (OSA), reversing the excessive daytime sleepiness associated with OSA. We investigated how polysomnography and maintenance of wakefulness test (MWT) predicted response to CPAP therapy in 10 patients with obstructive sleep apnea and 10 healthy controls. After a full polysomnography and MWT the patients were started on CPAP. MWT was repeated to quantify the treatment effect. Oxygen desaturation index and the percentage of slow wave sleep were the best predictors for baseline S1 latency in MWT. Baseline S1 latency in the MWT was the most important determinant of improvement in MWT S1 latency after CPAP, followed by the latency to 10 min of continuous nocturnal sleep, arousal index and CPAP use. We suggest that in mild sleep apnea, knowledge of sleep architecture is not necessary before deciding whether or not to initiate CPAP treatment.