Peripheral vascular function is impaired in people with obstructive sleep apnoea who are untreated compared with age-, weight- and sex-matched healthy controls.
Obstructive sleep apnoea (OSA) is a chronic respiratory disorder associated with endothelial dysfunction, increased sympathetic activation and increased cardiovascular risk. The standard treatment paradigm is continuous positive airway pressure (CPAP), however, patient adherence to CPAP is variable. It is unclear to what extent that poor adherence to CPAP therapy augments vascular endothelial function and reduces cardiovascular risk compared to excellent adherence. The main aim of this research is to investigate vascular endothelial function in OSA patients who are poorly-adherent to CPAP therapy. Nitric oxide (NO)-mediated, endothelium-dependent macrovascular and microvascular function (by brachial artery flow-mediated dilatation and forearm cutaneous thermal hyperaemia, respectively) and generalised microvascular function (by post-occlusion reactive hyperaemia) will be assessed in three obese OSA patient populations (high-adherence (n=20); low adherence (n=20); and, untreated (n=20)) and age-/BMI-matched OSA-free controls. We will also assess body composition, cardiovascular risk, lipid status and functional capacity. This research will evaluate treatment efficacy in patients who are poorly-adherent to CPAP treatment and could identify whether an alternative approach to their care should be explored.
Study Type
OBSERVATIONAL
Enrollment
45
Centre for Sport and Exercise Science, Sheffield Hallam University
Sheffield, South Yorkshire, United Kingdom
Sheffield Teaching Hospitals NHS FT
Sheffield, South Yorkshire, United Kingdom
Flow-mediated dilatation of the brachial artery
The brachial artery dilator response to a 5-min period of forearm arterial occlusion will be measured using a vascular ultrasound scanner and a 7-MHz linear array probe.
Time frame: Baseline only
GTN-mediated dilatation of the brachial artery
The brachial artery vasodilator response to a 400 microgram sublingual dose of glyceryl trinitrate will be measured using vascular ultrasound imaging.
Time frame: Baseline only
Forearm skin blood flow response to 5-min proximal-cuff arterial occlusion
Proximal arterial occlusion will be performed by inflating a blood pressure cuff placed on the upper arm to 200 mmHg for 5 min. After cuff deflation, the skin blood flow response will be measured using laser Doppler flowmetry.
Time frame: Baseline only
Forearm skin blood flow response to localised heating at 42 degrees C
A local heating unit on the forearm will be heated from 33 to 42 degrees C at a rate of 1 degree C every 10 s. Temperature will be held at 42 degrees C for 35 min. The increase in skin blood flow will be measured using a laser Doppler flowmetry probe placed in the centre of the local heating unit.
Time frame: Baseline only
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