Patent ID: 7438073

Claim:
An apparatus to assist a patient's respiration by delivering air to said patient through a mask, said mask being designed to be connected on a first extremity of a tube, said apparatus comprising: a control unit to adjust the pressure delivered by a blower of said apparatus, a first pressure sensor for measuring a first pressure, said first pressure sensor being connected to said control unit, and a second pressure sensor for measuring a second pressure at an air output of said blower, said second pressure sensor being connected to said control unit; wherein when a tube is connected between said apparatus and a calibrating shell with a traversing hole having a known airflow resistance coefficient K S , the air flows from the apparatus to said calibrating shell, and the measured pressures are sent to said control unit, which calculates a tube airflow resistance coefficient K T based on said first and second measured pressures and said known airflow resistance coefficient K S , wherein when a tube is connected to said mask and connected to said apparatus on a second extremity of said tube, the air flows from the apparatus to the mask, and said control unit calculates the airflow at said second extremity of the tube based on said first and second pressures and said airflow resistance coefficient K T of said tube.