Endothelial function in patients with obstructive sleep apnea syndrome but without hypertension

• Published in: Respiration Vol. 73; no. 6; p. 751
• Main Authors: Oflaz, Huseyin, Cuhadaroglu, Caglar, Pamukcu, Burak, Meric, Mehmet, Ece, Turhan, Kasikcioglu, Erdem, Koylan, Nevres
• Format: Journal Article
• Language: English
• Published: Switzerland 01-01-2006
• Subjects: Brachial Artery - diagnostic imaging; Brachial Artery - physiopathology; Circadian Rhythm - physiology; Disease Progression; Endothelium, Vascular - physiopathology; Endothelium, Vascular - surgery; Female; Humans; Hypertension - etiology; Male; Middle Aged; Polysomnography; Risk Factors; Sleep Apnea, Obstructive - complications; Sleep Apnea, Obstructive - diagnostic imaging; Sleep Apnea, Obstructive - physiopathology; Ultrasonography, Doppler; Vasodilation - physiology
• ISSN: 0025-7931
• DOI: 10.1159/000094183

Obstructive sleep apnea syndrome (OSAS) influences endothelial function and causes hypertension.
Our aim was to evaluate the role of endothelial dysfunction in the pathogenesis of hypertension in OSAS.
Twenty-three patients with OSAS but without hypertension and 15 healthy normotensive subjects were investigated. The presence or absence of OSAS was evaluated with a sleep study. Endothelial function was investigated with brachial artery ultrasound examination.
Baseline characteristics were equivalent between the two groups. Minimal oxygen saturation and apnea-hypopnea indexes in the OSAS and control groups were 62.9 +/- 16.5 versus 94.9 +/- 1.1% (p < 0.0001) and 53.1 +/- 20.3 versus 3.8 +/- 0.9 (p < 0.0001), respectively. There was not statistically significant difference between basal brachial artery diameters measured in the morning and in the evening in all groups. Flow-mediated dilation (FMD) values measured in the morning were lower than those measured in the evening in both OSAS patients and the control group: FMD of OSAS patients was 6.04 +/- 3.18% in the morning and 10.38 +/- 4.23% in the evening hours (p = 0.001), and FMD of control subjects was 10.9 +/- 2.6% in the morning and 13.9 +/- 2.32 in the evening hours (p = 0.002). Differences in FMD values measured both in the morning and evening hours in OSAS patients were lower compared with those in control subjects (p < 0.0001 in the morning hours and p = 0.003 in the evening hours).
We detected a prominent diurnal deterioration in endothelial function in normotensive OSAS patients compared with healthy subjects. This deterioration may occur due to ongoing hypoxemia during the night and it may be a possible cause of hypertension and atherosclerotic cardiovascular diseases in patients with OSAS.