Purpose: The objective of this study was to evaluate endothelial function and carotid intima media thickness (CIMT) in moderate to severe obstructive sleep apnea (OSA) without comorbidities.
Methods: It is an observational case control study in which endothelial function was assessed using flow-mediated dilatation (FMD) and peripheral arterial tonometry (PAT), and carotid artery ultrasound was used to measure CIMT in study group subjects that included 20 normotensive, non-diabetic, treatment naïve, and moderate to severe OSA patients, and 20 normotensive, non-diabetic, and non-OSA subjects served as a control group. Study was conducted in Polysomnography Laboratory, Department of Internal Medicine, All India Institute of Medical Sciences (AIIMS) Hospital, New Delhi.
Results: FMD was significantly lower in the moderate to severe OSA group compared to non-OSA group (mean ± SD, 8.3 ± 2.8 vs. 13.4 ± 4.1 %; p = 0.0001). Reactive hyperemia index (RHI) was also significantly lower in the OSA group (1.55 ± 0.27 vs. 2.01 ± 0.48, p = 0.0007). CIMT was observed to be significantly higher in the OSA group compared to the non-OSA group (0.54 ± 0.09 vs. 0.48 ± 0.08 mm; p = 0.049). In the OSA group, FMD, RHI, and CIMT did not show a significant correlation with OSA disease severity indices [apnea hypopnea index (AHI), oxygen desaturation index (ODI), and minimum O2 saturation].
Conclusion: Endothelial function in macrovascular and microvascular circulation is significantly impaired in moderate to severe OSA patients without comorbidities. These patients also show evidence of subclinical atherosclerosis, in the form of increased CIMT.
Keywords: Carotid intima media thickness; Endothelial function; Flow-mediated dilatation; Obstructive sleep apnea; Peripheral arterial tonometry; Reactive hyperemia index.