Air delivery system

An air delivery system, comprising a PAP device and at least a removable sensing device, wherein:

• the PAP device comprises:
• a flow generator for providing breathable gas at a pressure elevated above atmosphere;
• a patient interface, comprising:
• a gas delivery tube coupled to the flow generator;
• and
• a patient mask coupled to the gas delivery tube to receive breathable gas from the flow generator and to provide the gas, at a desired treatment pressure, to a patient's airway;
• a processor for controlling a magnitude of the treatment pressure provided by the flow generator;
• and
• a connector electrically connected to the removable sensing device;
• and
• the removable sensing device, comprises:
• at least a sensor for measuring a respiratory characteristic of the patient;
• a front-end analog circuit for processing the measurements from the sensor to generate signal inputs to the processor;
• and
• a connector electrically connected to the PAP device,
• wherein
• the sensor is integrated with the patient interface, so as to measure the respiratory characteristic in a path between the patient's upper airway and the flow generator, and
• wherein
• when the removable sensing device is separated from the PAP device, the PAP device enters a first operation mode, in which a preloaded program in the processor performs a first air delivery behavior to control the treatment pressure;
• and
• when the removable sensing device is coupled to the PAP device through the connectors respectively thereof, the PAP device enters a second operation mode, in which the preloaded program performs a second air delivery behavior for adjusting the treatment pressure in accordance with the respiratory characteristic from the signal inputs.