Improving 24-hour Blood Pressure in Obstructive Sleep Apnea

Obstructive Sleep Apnea

Telmisartan, Alpha-Lipoic Acid, Continuous Positive Airway Pressure, 24-hour blood pressure

This study examines the combined effects of an angiotensin receptor blocker (ARB), antioxidant supplementation, and continuous positive airway pressure (CPAP) therapy on the lowering of 24-hour blood pressure in persons with moderate to severe Obstructive Sleep Apnea (OSA). All participants will undergo CPAP therapy as prescribed by their doctor; however, half of the participants will receive the combined ARB and antioxidant treatment while the other half of the participants will receive a placebo.

OSA is a sleep disorder characterized by repetitive collapses (apneas) or partial collapses (hypopneas) of the upper airway. These airway obstructions result in intermittent reductions in arterial oxygen saturation (hypoxia), which causes a reflexive increase in sympathetic activation and systemic vasoconstriction. Resumption of breathing results in transient surges in blood pressure (BP) that can reach as high as 240/130 mm/Hg. OSA effects up to 24% of the adult population and evidence suggests a causal relationship between OSA and cardiovascular disease (CVD) development. While the exact mechanisms are unknown, data from animal and human models suggest that exposure to chronic intermittent hypoxia (IH) plays a significant role in the pathogenesis of cardiovascular comorbidity. Persons with OSA exhibit increased daytime sympathetic activity, markers of oxidative stress, and vasoactive hormones, particularly angiotensin II, that contribute to systemic vasoconstriction. These factors contribute to early endothelial dysfunction and contribute to sustained elevations in BP. While CPAP is the gold standard OSA treatment, adherence rates are low and evidence suggests that treatment does not reduce the rates of CVD in large population-based studies. Telmisartan is a receptor blocker for angiotensin II and not only has BP lowering effects, but also has unique anti-inflammatory properties and beneficial influences on endothelial function. The addition of an antioxidant supplement may increase the reactive oxygen species scavenging capacity and, in combination with ARB treatment, may provide more robust effects on BP in persons with OSA.

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