Characteristics of Patients With Severe Obstructive Sleep Apnea Who Maintain Slow-Wave Sleep

Abstract

Background and Objectives Obstructive sleep apnea (OSA) is a complex sleep-related respiratory disorder with various pathophysiology and clinical manifestations. Diagnosis and treatment considering only the number of respiratory events, such as sleep duration, may have limitations. The purpose of this study is to analyze the clinical and polysomnography (PSG) characteristics of patients with severe OSA in whom slow wave sleep (SWS) was well-maintained.Subjects and Method This study retrospectively analyzed 203 patients who underwent PSG due to suspected OSA. Severe OSA patients were classified into a SWS maintained group (SWS≥15%) and a SWS reduced group (SWS<15%), and their clinical records, PSG results, and heart rate variability (HRV) were compared.Results The SWS maintained group (n=27), compared to the SWS reduced group (n=58), had a significantly longer total sleep time (<i>p</i>=0.027) and lower wake after sleep onset (<i>p</i>=0.001), rapid eye movoement (REM) latency (<i>p</i>=0.007), non-supine apnea-hypopnea index (AHI, <i>p</i>=0.006), non-REM AHI (<i>p</i><0.001), arousal index (<i>p</i><0.001) and Epworth Sleepiness Scale (<i>p</i>=0.048). In addition, the SWS maintained group had a significantly low value in very low frequency in HRV than that of the SWS reduced group (<i>p</i>=0.046).Conclusion The SWS maintained group in the severe OSA showed better PSG and HRV results and reduced daytime sleepiness than those of the SWS reduced group.