Supine Sleep during Polysomnography and the Diagnosis of Obstructive Sleep Apnea

Abstract

Background: Since the supine position worsens obstructive sleep apnea (OSA) by promoting upper airway collapse, patients may avoid supine sleep in order to mitigate its effects. However, the avoidance of supine sleep during polysomnography (PSG) may result in a missed diagnosis of OSA. This study aims to examine the association between the presence/absence of supine sleep and the diagnosis of OSA during PSG. Methods: This cross-sectional analysis of a prospective cohort study analyzed the demographic, anthropometric, and PSG results in 243 patients who underwent PSG for suspected OSA. The crude and adjusted association between the absence/presence of supine sleep and OSA diagnosis during PSG was determined using Pearson Chi-square testing and binary logistic regression model fitting, respectively. Results: Adult patients suspected of OSA who had no supine sleep during PSG had statistically significant lower odds ratio [crude odds ratio (OR) = 0.26, 95%CI: 0.08, 0.81, p = 0.014] of being diagnosed with OSA compared to those who achieved some supine sleep. This association remained robust despite adjusting for known confounders such as age, BMI, and comorbid coronary heart disease (CHD) [adjusted OR = 0.13, 95%CI: 0.03, 0.48, p = 0.002]. Conclusion: Absence of supine sleep during PSG reduces the odds of an OSA diagnosis, even after adjusting for age, BMI, and CHD. Sleep laboratory policies should consider incorporating protocols that encourage patients to achieve some supine sleep during polysomnography in order to facilitate OSA diagnosis. complete or partial upper airway obstruction during sleep, resulting in respiratory arousals, sleep fragmentation, and/or oxygen desaturation [1]. OSA is the most common sleep-related breathing disorder, affecting 1017% of men and 3-9% of women in the United States [2]. Risk factors include obesity, age, male gender, menopause, wide neck circumference, adenotonsillar hypertrophy, and other craniofacial features that cause pharyngeal narrowing [3,4]. The supine position worsens OSA by promoting posterior displacement of the uvula, soft palate and tongue [5-11]. A case-control study found that sleeping in the supine posture doubled the magnitude of the apnea-hypopnea index (AHI) [7]. Up to 56% of 666 Israeli patients with OSA were found to have positional OSA, defined as a lateral respiratory disturbance index (RDI) less than half of the supine RDI [12]. These Israeli patients with positional OSA not only were, on average, two years younger but also had lower body mass index (BMI), less severe RDI, and better sleep than those with non-positional OSA [12]. A retrospective analysis of 3,813 patients who underwent fullnight polysomnography (PSG) at a sleep disorders center in Turkey reported an estimated 39.9% prevalence of positional OSA [13]. The patients with positional OSA were described to be younger and have less severe OSA compared to those with non-positional OSA [13]. A retrospective study of 326 US Veterans conducted in two sleep centers in the United States reported a decreasing prevalence of positional OSA with increasing severity of the disease: 49.5% for mild, 19.4% for moderate, ORiginal aRticlE