Factors Influencing Sleep Time With Oxygen Saturation Below 90% in Sleep-Disordered Breathing

Objectives/HypothesisTo determine factors influencing sleep time with oxygen saturation below 90% (ST90) in a population referred to a tertiary sleep center for assessment of possible sleep-disordered breathing (SDB). Study DesignRetrospective review of demographic and polysomnographic data of 731 consecutive patients with suspected SDB. MethodsBivariate correlation analyses were performed, and Spearman rho coefficients were calculated. Variables with a marginal association with ST90 (P<.05) in the bivariate analysis were included into the multiple regression analysis. ResultsThe distributions of SDB were as follows: normal/simple snoring, 18.2%; mild obstructive sleep apnea (OSA), 25.6%; moderate OSA, 17.4%; and severe OSA, 38.9%. The univariate analysis revealed a significant correlation between ST90 and age (r=0.204), body mass index (BMI) (r=0.440), arousal index (r=0.754), apnea-hypopnea index (AHI) (r=0.761), mean oxygen saturation (SaO(2)) (r=-0.506), and mean O-2 desaturation (r=0.858) (P<.001 for all parameters). In multiple regression analysis, age (P<.001), BMI (P=.040), male gender (P=.001), AHI (P<.001), mean SaO(2) (P<.001), and mean O-2 desaturation (P<.001) were found to be independent parameters influencing ST90. Furthermore, these parameters explained a significant proportion of variance in ST90 (R-2=0.794, F (6, 729)=464.65, P<.001). Although there was a strong correlation between AHI and ST90 (r=0.76, P<.001), a large variation of ST90 values was observed, especially within the severe OSA group. ConclusionsThe study results provide supporting evidence that patients with similar AHI may have quite different values of ST90, and thereby hypoxia. The stratification of patients with OSA according to AHI combined with ST90 may allow better identification of prognostic information. Level of Evidence4 Laryngoscope, 125:1008-1012, 2015