Physiological effects of treatments in obstructive sleep apnoea syndrome.

The original research in this thesis aimed to investigate physiological effects of different treatment approaches in obstructive sleep apnoea syndrome (OSAS). OSAS is a prevalent public health concern independently associated with increased cardiovascular risk. Specifically, study 1 examined the feasibility of conducting a pragmatic lifestyle intervention in patients reporting compliance with continuous positive airway pressure (CPAP) and collected provisional data about its efficacy, and study 2 investigated the physiological effects of low compliance to CPAP therapy in a four-arm observational study.The intervention in study 1 involved supervised exercise, dietary advice and behaviour change counselling. Primary outcome measures were recruitment, retention and compliance data and secondary outcome measures assessed anthropometrics, cardiovascular risk, quality of life and exercise capacity. Study 2 investigated macro-and microvascular function, anthropometrics, quality of life, cardiovascular risk and exercise capacity.The novel findings of this research were: 1) the lifestyle intervention was feasible to deliver; 2) the intervention improved key health outcomes such as exercise capacity (A +16%) and serum C-reactive protein (A -57%), which were maintained after 3 months of independence (A +22% and -57%, respectively); 3) self-reported CPAP compliance is an unreliable indicator of actual compliance; 4) it is difficult to recruit low-compliance patients onto research trials, and recruiting newly diagnosed patients is also difficult without interrupting the patient pathway; 5) vascular function seems impaired in low-compliance patients versus high-compliance patients, although further work is needed to confirm this.These findings contribute to the growing evidence base for the role of lifestyle intervention in OSAS, and provide provisional data on the effects of low compliance to CPAP therapy on vascular endothelial function. In summary, future research investigating pragmatic lifestyle interventions in OSAS and the physiological effects of low-compliance to CPAP is certainly warranted.