Effect of supine knee position on obstructive sleep apnea.

We previously reported a case of a middle-aged man whose obstructive sleep apnea (OSA) was virtually eliminated when he slept in the supine "knees up" position. In this study, we attempt to replicate this phenomenon in a group of volunteers with previously diagnosed OSA. Results indicated no significant improvement in OSA when sleeping supine knees up. Examination of distribution of within subjects' change [calculated as Respiratory Disturbance Index (RDI) in the "knees down" position vs RDI in the knees up position] indicated a trend for improvement in the latter (p=0.12, two-tailed probability). These results suggest that knee position is unlikely to be a robust intervention for OSA though they allow for the possibility that some patients may have a moderation of their condition by such a manipulation.