Patent ID: 7128069
Filing Date: 2006-10-31
Classification: A61B,A61M

Abstract:
1. In a CPAP apparatus having an electric motor, an impeller rotated by the motor, a patient interface, an air delivery conduit for delivering air from the impeller to the patient interface, a mechanism for determining the pressure in the patient interface, and a control mechanism that causes air to be delivered at a desired pressure to the patient interface, and that detects transitions between inhalation and exhalation of a respiratory cycle of a patient; a method of controlling the motor operation during a sequence of respiratory cycles comprising the steps of: (i) upon detection of the transition from inhalation to exhalation, de-energizing the motor to allow the motor to freewheel; (ii) when the pressure in the patient interface reaches a minimum pressure level during exhalation, re-energizing the motor and controlling its speed so to maintain the pressure at a level suitable for exhalation; and (iii) upon detection of the transition from exhalation to inhalation, increasing the motor speed to provide higher pressures in the patient interface suitable for inhalation, wherein during a ramp phase the motor speed is controlled in step (iii) so as to increase the pressure over successive respiratory cycles and to provide a substantially constant pressure during any single respiratory cycle while increasing the substantially constant pressure over successive respiratory cycles.