Obstructive sleep apnoea Nervous System Diseases Sleep apnoea
Conditions
Interventions
Patients on established CPAP treatment will be randomised to receive continued treatment on with CPAP or with sub therapeutic CPAP for two weeks. Patients will be blind to their allocation and will co
Sponsors
University of Oxford (UK)
Eligibility
Sex/Gender
All
Inclusion criteria
Inclusion criteria: 1. Objectively confirmed obstructive sleep apnoea (at the time of original diagnosis) with an oxygen desaturation index (ODI, >4% dips) or AHI of >20 (this threshold will exclude participants with borderline OSA, in whom there may be little experimental effect) 2. Currently >20/h oxygen desaturations (>4% dips) returning on any night during home nocturnal pulse oximetry performed for a 4-night period without CPAP, prior to entry into the study 3. Treated with CPAP for more than 12 months, minimum compliance 4h per night 4. ODI <10 during treatment (obtained during the preliminary week of oximetry monitoring, from the first 3 nights of oximetry monitoring on CPAP, before the 4 nights CPAP withdrawal) 5. Age between 20 and 75 years at trial entry 6. Written informed consent
Exclusion criteria
Exclusion criteria: 1. Previous ventilatory failure (awake resting arterial oxygen saturation 6kPa) or severe respiratory disorders other than OSA 2. Unstable, untreated coronary or peripheral artery disease, severe arterial hypertension(>180/110mmHg), severe arterial hypotension (<90/60mmHg) 3. Previously diagnosed with Cheyne-Stokes breathing 4. Current professional driver 5. History of any sleep-related driving accident or other accident 6. Acute inflammatory disease 7. Acute or chronic hepatic or renal disease 8. Known type 1 or 2 diabetes (likely to have low retinal reactivity even on CPAP) 9. Known severe vascular disease (likely to have low retinal reactivity even on CPAP) 10. Mental or physical disability precluding informed consent or compliance with the protocol 11. Non-feasible trial follow-up (for example, distance from follow-up centre, physical inability) 12. Epilepsy: flickering light used for retinal provocation could lead to a seizure 13. Lens opacities: this could lead to insufficient contrast and make it impossible to image the retinal vasculature
Design outcomes
Primary
| Measure | Time frame |
|---|---|
| To establish if OSA reduces retinal vascular reactivity. This will be done using retinal vascular response to flicker light protocol. Outcome measure will be the ?intervention effect? of OSA versus no OSA on retinal vascular reactivity following 14 days CPAP withdrawal, with appropriate controlling for baseline reactivity, OSA severity, BMI and cardio-vascular co-morbidities (via Pocock risk score). | — |
Secondary
| Measure | Time frame |
|---|---|
| Whether any change in retinal vascular reactivity correlate with OSA severity and/or change in markers of sympathetic activity. This will be measured by correlation between change in retinal vascular reactivity (from baseline to two weeks in the CPAP withdrawal arm), with the severity of OSA (>4%ODI) returning, and/or change in both heart rate and blood pressure in the same group (from home measurements over penultimate 3 days), and/or urinary catecholamines. Tertiary outcomes will be whether any change in retinal vascular reactivity and retinal vessel oxygen saturation variables correlate with changes in mRNA expression. This will be measured by collection of blood samples for later analysis of mRNA expression. | — |
Countries
England, United Kingdom
Outcome results
None listed