Randomized controlled trial (therapeutic vs. placebo CPAP) including 46 patients with obstructive sleep apnea (OSA) to define the physiological effects of continuous positive airway pressure (CPAP) therapy withdrawal on myocardial perfusion and dermal and renal microvascular function during a 2 week period.

Inclusion criteria:

• Objectively confirmed OSA (at the time of original diagnosis) with an oxygen desaturation index (ODI, =4% dips) of >20/h and an ESS of >10.
• Currently >20/h oxygen desaturations (=4% dips) during an ambulatory nocturnal pulse oximetry performed at the end of a 4-night period without CPAP.
• Treated with CPAP for more than 12 months, minimum compliance 4h per night, AHI<10 with treatment (according to CPAP machine download data).
• Current ESS <10.

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.
• Age <20 or >75 years at trial entry.
• Acute inflammatory disease