Scientific Investigations
The Impact of Body Posture and Sleep Stages on Sleep Apnea Severity in Adults
http://dx.doi.org/10.5664/jcsm.2258
Nathaniel A. Eiseman, B.S.1; M. Brandon Westover, M.D., Ph.D.1; Jeffrey M. Ellenbogen, M.D., F.A.A.S.M.1,2; Matt T. Bianchi, M.D., Ph.D.1,2
1Neurology Department, Massachusetts General Hospital, Boston, MA; 2Division of Sleep Medicine, Harvard Medical School, Boston, MA
Study Objectives:
Determining the presence and severity of obstructive sleep apnea (OSA) is based on apnea and hypopnea event rates per hour of sleep. Making this determination presents a diagnostic challenge, given that summary metrics do not consider certain factors that influence severity, such as body position and the composition of sleep stages.
Methods:
We retrospectively analyzed 300 consecutive diagnostic PSGs performed at our center to determine the impact of body position and sleep stage on sleep apnea severity.
Results:
The median percent of REM sleep was 16% (reduced compared to a normal value of ~25%). The median percent supine sleep was 65%. Fewer than half of PSGs contained > 10 min in each of the 4 possible combinations of REM/NREM and supine/non-supine. Half of patients had > 2-fold worsening of the apnea-hypopnea index (AHI) in REM sleep, and 60% had > 2-fold worsening of AHI while supine. Adjusting for body position had greater impact on the AHI than adjusting for reduced REM%. Misclassification—specifically underestimation of OSA severity—is attributed more commonly to body position (20% to 40%) than to sleep stage (~10%).
Conclusions:
Supine-dominance and REM-dominance commonly contribute to AHI underestimation in single-night PSGs. Misclassification of OSA severity can be mitigated in a patient-specific manner by appropriate consideration of these variables. The results have implications for the interpretation of single-night measurements in clinical practice, especially with trends toward home testing devices that may not measure body position or sleep stage.
Citation:
Eiseman NA; Westover MB; Ellenbogen JM; Bianchi MT. The impact of body posture and sleep stages on sleep apnea severity in adults. J Clin Sleep Med 2012;8(6):655-666.
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