Patent ID: 8899232

Claim:
A method of controlling a pressure of air delivery by a CPAP apparatus; wherein said CPAP apparatus includes an electric motor, an impeller driven by the motor for delivering air to a patient interface, a sensor for determining the pressure in the patient interface, and a controller (1) to control the pressure of air delivery to the patient interface and (2) to detect transitions between inhalation and exhalation of a respiratory cycle of a patient, comprising the steps of: (i) operating said electric motor, thereby driving said impeller for delivering air to said patient interface at a pressure above atmospheric; (ii) upon detection of the transition from inhalation to exhalation, ceasing driving said impeller and causing said impeller to freewheel; (iii) upon the sensor sensing that the pressure in the patient interface reaches a minimum pressure level during exhalation, re-starting driving said impeller to maintain the pressure at a level suitable for exhalation; and (iv) upon detection of the transition from exhalation to inhalation, increasing driving said impeller to provide an increased pressure in the patient interface suitable for inhalation.