Effects of Suboptimal CPAP Therapy on Symptoms of Obstructive Sleep Apnoea

Effects of Suboptimal Use of CPAP Therapy on Symptoms of Obstructive Sleep Apnoea

Obstructive sleep apnoea (OSA) is a highly prevalent sleep-related breathing disorder. The most effective treatment for OSA is continuous positive airway pressure (CPAP). CPAP therapy has been shown to significantly reduce subjective sleepiness and blood pressure in patients with symptomatic OSA. Its effectiveness tends to depend on its nightly usage and a commonly held view is that CPAP should be used for at least 4h/night. However, previous studies have estimated that a considerable proportion of CPAP users fail to achieve this. In addition, there is inadequate evidence to support this apparent threshold effect and so it is unclear whether such patients actually benefit from treatment or whether they could be withdrawn from CPAP, thus substantially reducing health care costs, or encouraged to increase their nightly usage of CPAP.

The aim of the proposed project is to study the effect of CPAP withdrawal on subjective sleepiness in OSA patients using CPAP for less than 4h/night on average. We hypothesize that two-week CPAP withdrawal in patients with 3-4h/night use will lead to a return of OSA-related symptoms. This trial will better establish the minimum level of CPAP adherence which could generally be regarded as effective in reducing OSA-related symptoms.

Inclusion Criteria:

• Objectively confirmed OSA (at the time of original diagnosis) with an oxygen desaturation index (ODI, ≥4% dips) of ≥15/h and an ESS of >10.
• Currently ≥15/h oxygen desaturations (≥4% dips) during an ambulatory nocturnal pulse oximetry performed at the end of a 4-night period without CPAP.
• Eligible patients must have been treated with CPAP for more than 12 months with a mean compliance between 3 and 4h/night. Apnoea-hypopnoea index (AHI) must be less than 10 with treatment (according to CPAP machine download data).

Exclusion Criteria:

• Previous ventilatory failure (awake PaO2<9.0kPa or arterial PaCO2>6kPa).
• Unstable, untreated coronary or peripheral artery disease, severe arterial hypertension (>180/110mmHg).
• Previously diagnosed with Cheyne-Stokes breathing.
• Current professional driver.
• Age < 20 or > 75 years at trial entry.