To determine if auto-adjusting positive airway pressure (APAP) would be better tolerated on the basis of delivering a lower mean pressure in patients with mild to moderate obstructive sleep apnoea syndrome (OSAS).

Patients spent 8 weeks on continuous positive airway pressure (CPAP) and 8 weeks on APAP in a randomized crossover design.

Respiratory Sleep Disorders Unit in a University Hospital and the patient's home.

Twenty-nine patients with newly diagnosed mild to moderate OSAS (apnoea-hypopnoea frequency of 5–30 events/hour) were studied.

N/A.

Overnight polysomnography and Epworth Sleepiness Scale were recorded at baseline and at the end of each treatment period in addition to patient preference for device, side effects, and objective compliance. No differences were found in polysomnographic variables or Epworth Sleepiness Scale scores between the 2 treatment modes, but all variables were significantly improved from baseline values. Mean APAP pressure levels were significantly lower than CPAP (6.3 ± 1.4 vs 8.1 ± 1.7 cm H₂O, p < .001). Patient compliance was similar with both treatments. More patients requiring higher fixed pressure (≥ 8cm H₂O) preferred APAP, whereas those requiring lower pressure (< 8 cm H₂O) preferred CPAP (p = .03). Follow-up after 18 months of therapy indicated that 76% of subjects continued to be compliant, with a nightly use of 5.8 ± 1.9 hours per night, despite high levels of minor side effects.

APAP and CPAP are equally effective in managing patients with mild to moderate OSAS, but device preference may be influenced by fixed pressure requirements.