Supine position related obstructive sleep apnea in adults: Pathogenesis and treatment

The most striking feature of obstructive respiratory events is that they are at their most severe and frequent in the supine sleeping position: indeed, more than half of all obstructive sleep apnea (OSA) patients can be classified as supine related USA. Existing evidence points to supine related USA being attributable to unfavorable airway geometry, reduced lung volume, and an inability of airway dilator muscles to adequately compensate as the airway collapses. The role of arousal threshold and ventilatory control instability in the supine position has however yet to be defined. Crucially, few physiological studies have examined patients in the lateral and supine positions, so there is little information to elucidate how breathing stability is affected by sleep posture. The mechanisms of supine related USA can be overcome by the use of continuous positive airway pressure. There are conflicting data on the utility of oral appliances, while the effectiveness of weight loss and nasal expiratory resistance remains unclear. Avoidance of the supine posture is efficacious, but long term compliance data and well powered randomized controlled trials are lacking. The treatment of supine related USA remains largely ignored in major clinical guidelines. Supine USA is the dominant phenotype of the USA syndrome. This review explains why the supine position so favors upper airway collapse and presents the available data on the management of patients with supine related USA. (C) 2013 Elsevier Ltd. All rights reserved.