Patent ID: 8272380
Filing Date: 2012-09-25
Classification: A61M

Abstract:
1. A method of compensating for leakage in a ventilation system during delivery of gas from a medical ventilator to a patient comprising: estimating leakage from the ventilation system during delivery of gas to the patient based on measurements of at least one of pressure and flow; modeling the leakage as a first leakage component through a first orifice of a fixed size and a second leakage component through a second orifice of a varying size, wherein the first and second leakage components are different functions of one or more of instantaneous pressure and instantaneous flow in the ventilation system; estimating instantaneous lung flow of gas exhaled or inhaled by the patient during an exhalation phase; identifying a target pressure trigger threshold indicative of patient inspiratory effort; monitoring an instantaneous pressure at a location in the ventilation system based on one or more measurements of instantaneous pressure or instantaneous flow in the ventilation system; generating a leak-compensated pressure trigger condition based on the monitored instantaneous pressure, the target pressure trigger threshold, the estimated instantaneous lung flow and the second leakage component; and using the leak-compensated pressure trigger condition to determine when the patient has begun to initiate an inhalation.