ABSTRACT: Importance:The anatomic mechanisms underlying positional vs nonpositional obstructive sleep apnea (OSA) are poorly understood and may inform treatment decisions. Objective:To examine drug-induced sleep endoscopy (DISE) findings in the supine vs nonsupine body positions in positional and nonpositional obstructive sleep apnea. Design, Setting, and Participants:A cross-sectional study of 65 consecutive eligible adults with OSA undergoing DISE without marked tonsillar hypertrophy, including 39 with positional OSA (POSA) and 26 with nonpositional OSA (N-POSA) was conducted in a sleep surgery practice at a tertiary academic medical center. Exposures:Drug-induced sleep endoscopy performed in the supine vs nonsupine body position. Main Outcomes and Measures:Drug-induced sleep endoscopy findings were scored separately for the supine and lateral body positions using the VOTE classification (velum, oroparyngeal lateral walls, tongue, epiglotis) and with identification of a single primary structure contributing to airway obstruction. Velum-related obstruction was separated into anteroposterior and lateral components. Results:The 65 study participants had a mean (SD) age of 52.4 (11.7) years, and 55 (84.6) were men. Mean (SD) body mass index (BMI, calculated as weight in kilograms divided by height in meters squared) was 27.2 (3.1), with only 9 (14%) of 65 participants having a BMI greater than 30. The supine body position was associated with greater odds of anteroposterior velum- (odds ratio [OR], 7.28; 95% CI, 3.53-15.01), tongue- (OR, 29.4; 95% CI, 12.1-71.5), and epiglottis-related (OR, 11.0; 95% CI, 1.3-92.7) obstruction in the entire cohort, with similar findings in the POSA and N-POSA subgroups. The supine body position was associated with a lower odds of oropharyngeal lateral wall-related (OR, 0.22; 95% CI, 0.07-0.70) obstruction in the N-POSA subgroup, whereas there was no increase in the overall sample or the POSA subgroup. The oropharyngeal lateral walls were a common primary structure causing obstruction, especially in the lateral body position. Conclusions and Relevance:In a study population of primarily nonobese adults, DISE findings differed based on body position, generally corresponding to gravitational factors. Treatments that address velum- and tongue-related obstruction successfully may be more effective in the POSA population.
