Endocrine dysfunction in obstructive sleep apnoea and the effect of continuous positive airway pressure therapy: studies with a novel automated blood sampling system

    Research output: ThesisDoctoral Thesis

    230 Downloads (Pure)

    Abstract

    [Truncated abstract] Obstructive sleep apnoea (OSA) is a common condition that is associated with repetitive cycles of upper airway obstruction during sleep resulting in recurrent hypoxia/hypoxaemia and fragmented sleep. Obesity is a major risk factor. The current gold standard of treatment is with continuous positive airway pressure (CPAP) therapy. OSA is associated with significant medical comorbidity including hypertension, the metabolic syndrome, type II diabetes mellitus and cardiovascular disease. These are similar to the complications of hypercortisolaemia. Recurrent nocturnal hypoxaemia, fragmented sleep and the physical effort of attempting to breathe against an obstructed upper airway could be expected to activate the hypothalamic-pituitary-adrenal (HPA) stress axis. Cortisol, the principal effector of the HPA axis, is synthesised and secreted by the adrenal glands in response to adrenocorticotrophic hormone (ACTH) from the pituitary gland. Plasma levels of these hormones are regulated by a complex feedback loop. They are secreted in an ultradian or burst-like manner resulting in fluctuating plasma levels throughout the 24 hour (hr) cycle and this pulsatile secretion is important in glucocorticoid signalling. I hypothesised that OSA is a stressor activating the HPA axis and that this may be manifest by alterations in the ultradian rhythms of ACTH and cortisol. To test this hypothesis a computer-driven automated blood sampling system was designed to measure these stress hormones repetitively over 24-hours in humans, under basal conditions. The automated blood sampling system incorporates a peristaltic pump, fraction collector and standard infusion pump together with a custom built electronic control unit linked to a personal computer. The system was validated using five healthy volunteers in whom 10 minute (min) blood samples for cortisol were collected over 24 hr, with two having additional concomitant ACTH sampling.
    Original languageEnglish
    QualificationDoctor of Philosophy
    Publication statusUnpublished - 2010

    Fingerprint

    Dive into the research topics of 'Endocrine dysfunction in obstructive sleep apnoea and the effect of continuous positive airway pressure therapy: studies with a novel automated blood sampling system'. Together they form a unique fingerprint.

    Cite this