Somnolence level predictors in patients with obstructive sleep apnea.

Excessive daytime sleepiness (EDS) is the obstructive sleep apnea syndrome (OSAS) most frequent symptom. The relationship between the level of daytime sleepiness and standard polysomnographic variables (i.e., apnea/hypopnea index [AHI] and oxygen saturation SaO(2)) has been the subject of a number of studies. To date, the results have been inconsistent. The goal of this study is to assess the variables significantly related with daytime sleepiness severity. The variables chosen were: AHI, percentage of total time that the subject remains with arterial oxygen saturation level below 90% (SaO2 < 90%), minimum oxygen saturation (SaO2 m), body mass index (BMI), and age. The study sample was composed of 51 obstructive sleep apnea patients selected from a medical centre. Subjects completed using the Epworth Sleepiness Scale (ESS) to determine daytime sleepiness. The OSAS was diagnosed by conventional polysomnography. The results indicated significant correlations between level of daytime sleepiness and age (r=.302; p <.05), BMI (r=.339, p <.05), SaO2 m (r=-.393, p <.01) and SaO2 < 90% (r=.492, p <.01). Significant correlations were also found between AHI and SaO2 < 90% (r=.314, p <.05), BMI and SaO2 < 90% (r=-.387; p <.05), and SaO2 m and SaO2 < 90% (r=-.746; p <.01). No significant correlation was detected between AHI and level of daytime sleepiness. According to the results, the percentage of total time that the subject remains with arterial oxygen saturation level below 90% (SaO2 < 90%) is the best predictor of daytime sleepiness severity.