System and method for determining ventilator leakage during stable periods within a breath

A respiratory gas supply system comprising:

• a pressure generating system configured to control flow of breathing gas through a patient circuit and a patient interface to a patient;
• and
• a computer controller communicatively coupled to the pressure generating system for adjusting the flow of breathing gas delivered to the patient, the computer controller configured to:
• identify a stable period within at least one of an inhalation phase and an exhalation phase of a breath;
• calculate leakage information using data obtained during the stable period identified by the stable period identification module;
• calculate, during unstable periods within the breath or a later breath, an instantaneous leakage rate based on the leakage information;
• and
• adjust at least one of a pressure and a flow delivered to the patient based on the determined leakage rate.

A method for determining leakage from a respiratory gas supply system, the respiratory gas supply system having a controller adapted for providing respiratory gases to a breathing patient, comprising:

• identifying, by the controller, at least one stable period within a breath of a patient;
• calculating leakage information from pressure and flow data obtained during the at least one stable period;
• subsequent to the at least one stable period, estimating, by the controller, a leakage from the respiratory gas supply system based on the leakage information and current data;
• and
• adjusting at least one of a pressure and a flow delivered to the patient based on the determined leakage.