Importance of sleep stage- and body position-dependence of sleep apnoea indetermining benefits to auto-CPAP therapy

The influence of sleep stage- and body position-dependence of sleep apnoea on treatment efficacy and compliance between conventional continuous positi ve airway pressure (CPAP) and auto CPAP therapy was evaluated. Thirty-three newly treated sleep apnoea hypopnoea syndrome (SAHS) patients were randomly allocated to conventional or auto-CPAP therapy. Six patients of each treatment group were classified as having sleep stage- and body pos ition-dependent obstructive breathing abnormalities according to the result s of the baseline sleep study. After 3 weeks of treatment, the Epworth sleepiness score tended to be highe r (p=0.08) and the ability to stay awake lower (p=0.02) in patients with de pendent breathing abnormalities treated with fixed CPAP, than in the other patients. The effective pressure/time index was significantly lower in slee p stage- and body position-dependent patients treated with fixed CPAP, than in the other patients (p=0.02). The number of hours the machine was turned on and a positive pressure applied, tended to be smaller in dependent pati ents treated with fixed CPAP than in independent patients of this treatment group and in patients treated with auto-CPAP. A night-to-night variability , index (VI) of positive pressure changes was obtained in the auto-CPAP gro up. This index significantly decreased with time in the dependent patients while it remained unchanged in the independent group. It is concluded that auto-continuous positive airway pressure may have spec ific indications in a subset of obstructive sleep apnoea patients with slee p stage- and body position dependent nocturnal breathing abnormalities.