Patent ID: 6539940
Filing Date: 2003-04-01
Classification: A61M

Abstract:
A non-invasive pressure support system comprising;a pressure generator adapted to provide a flow of breathing gas; a conduit having a first end coupled to an output of the pressure generator and adapted to carry the flow of breathing gas and a second end; a non-invasive patient interface device coupled to the second end of the conduit and adapted to communicate the flow of breathing gas with an airway of a patient responsive to the interface device being donned by a patient, wherein the conduit and the interface device define a pressurized system; a continuously open exhaust vent defined in the conduit at a location near the patient interface or in the patient interface to provide a flow of exhaust gas from the pressurized system to ambient atmosphere; a flow transducer operatively coupled to the conduit to measure a total flow of breathing gas passing therethrough; a pressure sensor coupled to the conduit or the patient interface so as to measure a pressure P(t) of gas within the pressurized system; and a controller adapted to receive an output of the flow transducer and the pressure sensor, wherein the controller calculates, based on the output of the flow transducer and the pressure sensor, a characteristic K of a hypothetical orifice, which represents an orifice through which all leakage of gas from the pressurized system occurs, and wherein the controller determines a total instantaneous flow of the leakage of gas from the pressurized system based on the characteristic K of the hypothetical orifice.