Patent ID: 11938268
Assignee: RESMED PTY LTD
Field: Medical technology (Instruments)
Classification: CPC A  H | IPC A

Claim 15:
16. An apparatus for treating a respiratory disorder in a patient, the apparatus comprising: a motor-blower configured to generate a supply of air at a positive pressure relative to ambient pressure; a humidifier configured to provide water vapour to humidify the supply of pressurized air; a tube removably connected to the humidifier on one end and a patient interface on another end, the tube including one or more heating wires extending along the length of the tube and configured to heat the humidified supply of breathable air passed though the tube and one or more sensor wires extending along the length of the tube and coupled to a sensor configured to measure a property of the humidified supply of breathable gas in the tube; a controller including circuitry configured to control power provided to the one or more heating wires, control operation of the motor-blower, control operation of the humidifier; a set of low pass filters coupled between the sensor wires and the controller, and a set of high pass filters coupled between the sensor wire and the ground; and wherein the power provided to the heating wires comprises a pulse width modulated power signal and the one or more low pass filters are configured to filter frequencies near the frequencies of the pulse width modulated power signal and frequencies higher than the frequencies of the pulse width modulated power signal.