[Extent of variations in minimal CPAP pressure requirements during a single night]

The frequency of apnoeic events during sleep depends on posture and sleep stage. This is due to a change of upper airway size and upper airway closing pressures during different postures and sleep stages. The extent of the change of the necessary "splinting" pressure during nasal CPAP therapy for obstructive sleep apnoea is unknown. We titrated during CPAP therapy the minimal effective pressure, depending on sleep stage and posture. The necessary pressure fluctuated, depending on the patient, between 3 and 10 mbar. The highest pressure was not solely achieved during supine position and REM; some patients needed higher pressures under other circumstances.