RESUMEN
BACKGROUND AND OBJECTIVES: Obstructive sleep apnea (OSA) patients are classified into positional patients with supine apneahypopnea index (AHI) that is at least twice as high as the non-supine AHI, and non-positional patients with a supine AHI that does not reach double values of the non-supine AHI. We determined the prevalence of positional sleep apnea and compared clinical characteristics between positional and non-positional OSA patients. SUBJECTS AND METHOD: This was a cross-sectional study at a tertiary rhinologic referral center. We evaluated 113 patients whose AHI were over 5 and whose sleep time of supine, nonsupine position were over 15 minutes as a result of overnight polysomnography taken from January 2007 to July 2008. The body position of patients was confirmed with sleep position sensor and direct observation. RESULTS: Positional sleep apnea was seen in 14/22 (63.64%) with mild sleep apnea (AHI, 5 to 15/h), 16/36 (44.44%) with moderate sleep apnea (AHI, 15 to 30/h), 14/55 (25.45%) with severe sleep apnea (AHI, > or =30/h) and over all prevalence of positional sleep apnea in this study is 38.9%. The severity of OSA, weight, waist and waist to hip ratio (WHR) is related to the positional tendency. CONCLUSION: The result of this study revealed that positional sleep apnea was more common in patients with mild OSA and the positional tendency of OSA patients was affected by central obesity