Endothelial function in normotensive men with obstructive sleep apnea before and 6 months after CPAP treatment

To evaluate endothelium-dependent flow-mediated dilation (FMD) and endothelium-independent nitroglycerin (NTG)-induced dilation of the brachial artery with Doppler ultrasound in patients with obstructive sleep apnea (OSA) and impact of six months of continuous positive airway pressure (CPAP) treatment.

A prospective, controlled, observational study.

Single-site, clinic-based.

Twenty-nine normotensive men with OSA (apnea-hypopnea index [AHI], mean +/- SD, 60.4 +/- 22.1-h), and 17 men without OSA (AHI 2.5 +/- 0.6-h).

Six months of CPAP therapy in OSA patients.

FMD was lower in patients with OSA compared with in controls (7.19 +/- 1.78% vs 10.93 +/- 2.59%; P < 0.001) while NTG-induced vasodilation was similar in both groups (13.75 +/- 1.01% vs 14.25 +/- 1.83%; n.s.). An inverse relationship was found between FMD and AHI adjusted for age and body mass index (BMI) (beta = - 0.05, P < 0.001). Following 6 months of CPAP treatment in the OSA group, FMD was increased from 7.38 +/- 2.06% to 10.45 +/- 1.68; P = 0.001) in 20 patients compliant with the device whereas the corresponding values did not change in the non-user group (7.08 +/- 1.50% vs 7.26 +/- 1.01%). No significant changes were observed regarding the NTG-induced vasodilation after CPAP compared with the baseline values.

Our results confirm the previous reports suggesting impaired endothelium-dependent FMD in OSA, and additionally document the sustained improvement in endothelial function after 6 months of CPAP treatment in complaint patients.