Determination of mask fitting pressure and correct mask fit

摘要

CPAP treatment apparatus ( 10 ), as one form of positive pressure ventilatory assistance, is disclosed. A turbine/blower ( 14 ), operated by a mechanically coupled electrical motor ( 16 ), receives air or breathable gas at an inlet ( 18 ) thereof, and supplies the breathable gas at a delivery pressure to a delivery tube/hose ( 20 ) having connection at the other end thereof with a nose mask ( 12 ). A microcontroller ( 38 ) has an operational "Mask-Fit" mode. An initial constant pressure level is applied by the blower ( 14 ) to the mask ( 12 ). If the functional mode is a Manual mode, then the mask-fit test pressure is the current 'set' pressure. If the functional mode is the Automatic Titration mode, the mask-fit test pressure is the 95th percentile pressure of the previous session, otherwise it is the base treatment pressure, e.g. 10-12 cm H₂O. This constant pressure is applied for a period of time, typically 1-3 minutes. The microcontroller ( 38 ) continuously determines mask leak as the value, f_LEAK, from a flow sensor ( 32 ), comparing this to a threshold, and providing the patient with a visual indication of degree of leak. In this way the patient can manipulate the mask to ensure correct fitting as indicated by the appropriate message or indication.