RESUMO
PURPOSE: In obstructive sleep apnea-hypopnea syndrome (OSAS), airway collapses and vibrations cause local and systemic inflammatory response and oxidative stress (OS). Our objective was to determine the presence of OS in the airway of patients with OSAS compared with controls without OSAS and determine its relation to treatment with CPAP and other clinical variables. METHOD: We performed a prospective observational case-control study with repeated measures. We recruited consecutive patients with SAHS diagnosed using complete polysomnography, and a parallel control group. We collected a sample of exhaled breath condensate (EBC) prior to nasal continuous positive airway pressure (CPAP) treatment and again after 4 months. The marker of OS used was 8-isoprostane (8-IPN). The variables analyzed were age, sex, anthropometric variables, apnea-hypopnea index (AHI), snoring, oxygenation, and polysomnographic variables. RESULTS: The study included 20 patients and 10 controls. In cases, the initial value of 8-IPN was 6.8 (1.9), and after nasal CPAP, it was 5.3 (1.2) pg/ml (p = 0.02). In controls, the value of 8-IPN was 5.6 (1.1) pg/ml (p = 0.04 compared to initial values). 8-IPN showed significant correlation with snoring, AHI, BMI, nocturnal desaturation index, and non-REM sleep. On multivariate analysis, only snoring was a significant predictor of 8-IPN. CONCLUSIONS: Snoring, and not OSAS severity, could be the phenomenon underlying the presence of local OS measured in the airway of patients with OSAS.