Clinical trial in patients with obstructive sleep apnoea that are randomised to either continue or withdraw continuous positive airway pressure therapy to identify a disease-specific exhaled breath pattern by mass spectrometry.

Randomised placebo-controlled trial (therapeutic vs. subtherapeutic continuous positive airway pressure [CPAP]) including 30 OSA patients to define the effects of CPAP withdrawal (subtherapeutic CPAP) on the composition of exhaled breath analysed by mass spectrometry for identification of OSA specific markers.

Inclusion Criteria:

• Confirmed OSA (at the time of original diagnosis) with an oxygen desaturation index (ODI) of >20/h.
• Currently >20/h oxygen desaturations (≥4% dips) during an ambulatory nocturnal pulse oximetry performed on the last night of a 4-night period without CPAP.
• Treated with CPAP for more than 12 months, minimum compliance 4h/night, apnoea-hypopnoea index (AHI) <10 with treatment (according to CPAP- download) and current ESS <10.
• Age between 20 and 75 years at trial entry.

Exclusion Criteria:

• Previous ventilatory failure (awake SpO2 <93% and PaCO2>6kPa).
• Unstable, untreated coronary or peripheral artery disease, severe arterial hypertension or hypotension (>180/110 or <90/60mmHg)
• Previously diagnosed with Cheyne-Stokes breathing.
• Current professional driver; any previous sleep related accident.
• Acute inflammatory disease.
• Acute or chronic hepatic disease.
• Renal failure or renal replacement therapy.
• Use of inhaled drugs.