Background:Although continuous positive airway pressure therapy (CPAP) is the treatment of choice for obstructive sleep apnoea syndrome (OSAS), there is a portion of patients in which CPAP is not usable. Bilevel treatment serves as an alternative for these patients. For uncomplicated OSAS, auto-adjusting CPAP based on the forced oscillation technique (APAPFOT) has proved to be equally as effective as constant CPAP, and is prefered by the patients. The aim of this study was to investigate the question whether, in the event of primary CPAP intolerance, high pressures (>12 cm H2O) or SAS with >10% central respiratory disorders, APAPFOT is as effective as bilevel therapy in reducing respiratory disturbances.Material/Methods:27 patients (23m, 4 f, age 57.2±13.1 years, BMI 33.5±7.8 kg/m2) were treated with bilevel and APAPFOT for 6 weeks each in a prospective randomized cross-over study. The efficacy of the treatment modes was examined polysomnographically.Results:Both modalities significantly improved the respiratory disturbances (AHI: baseline 49±27.3/h, bilevel 9.8±12.5, p

Keywords: Air Pressure, Continuous Positive Airway Pressure - instrumentation, Continuous Positive Airway Pressure - methods, Cross-Over Studies, Polysomnography, Sleep Apnea, Obstructive - therapy