Patent ID: 8056559

Claim:
An apparatus for automatically determining a flow characteristic at a mask while said mask is engaged with a patient being delivered positive airway pressure treatment, comprising: a mask; a conduit; a controllable blower for supplying breathable gas at a pressure above atmospheric to said mask through said conduit; a flow sensor configured and arranged to sense flow and to generate a flow signal indicative of airflow through the mask; a pressure sensor positioned remote from the mask and configured to generate a pressure signal indicative of the pressure remote from the mask; and a processor ( 1 ) to control the blower to deliver a plurality of flow levels in a predetermined range; ( 2 ) to create a table of pressure signals and corresponding flow signals determined when delivering a plurality of flow levels in a predetermined range and when the mask is not engaged to a patient; and ( 3 ) to determine from the created table and a generated flow signal a flow characteristic at the mask during delivery of positive airway pressure treatment to a patient.