Beneficial effects of CPAP treatment on endothelial function in patients with mild to moderate obstructive sleep apnea

Abstract

Purpose: Obstructive sleep apnea (OSA) is associated with endothelial dysfunction, which may contribute to the onset of atherosclerosis and associated complications. Flow-mediated dilation (FMD) is routinely used as a noninvasive technique to evaluate endothelial function. The aim of the study was to investigate the impact of continuous positive airway pressure (CPAP) treatment on endothelial function in OSA. Methods:A cohort of twenty-five patients with OSA (age 53.8 ± 11.8 years) and 17 age-matched controls (age 48.1 ± 15.1 years) were included in the study. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) were measured using a plethysmography. FMD was evaluated using high-resolution ultrasound with a 7.5 MHz linear array transducer. The % FMD index was calculated as (maximum diameter -baseline diameter) / (baseline diameter) × 100. Maximum carotid intimamedia thickness (max IMT) was also determined.Results: % FMD was significantly lower in OSA patients compared to controls (3.3 ± 1.9 vs. 5.0 ± 1.9, P=0.009) while SBP, DBP, and max IMT did not significantly differ between the two groups. In OSA patients showing good CPAP adherence (defined as CPAP usage ≥4 h/night and 70% of nights), % FMD improved from 1.7 to 3.1 in the absence of any significant decrease in SBP or DBP. Conclusion:Although there was no difference in max IMT between OSA patients and control subjects, % FMD was significantly decreased in OSA patients. More particularly, our results suggest that good adherence to CPAP treatment might reverse endothelial dysfunction in these patients.