Patent ID: 8920333

Claim:
A method for generating a signal that mirrors changes in the level of effort exerted by respiratory muscles of patients on mechanical ventilatory support (Signal), comprising: monitoring airway pressure (P aw ), rate of gas flow (F), and volume of gas flow (V) of the patient; inputting P aw , F and V data collected to a computer with said computer performing the following processes on the collected data; calculating a composite pressure signal that mirrors changes in the level of effort exerted by respiratory muscles of patients on mechanical ventilatory support (Signal) from the relationship: Signal=current V*K v +current F*K F −current P aw , wherein, K F is a coefficient that converts flow into equivalent resistive pressure units and K v is a coefficient that converts volume into equivalent elastic pressure units; said calculation begins using assumed (arbitrary) values for K F and K v while subsequently, as more data is analysed, utilizing Patient-Specific values; calculating a Patient-Specific K F from elapsed data by determining the value that minimizes step changes in calculated Signal at the time of ventilator triggering and/or cycling-off; calculating a Patient-Specific K v from elapsed data by steps comprising: scanning of stored F or Paw information, and/or the time derivative thereof, during the exhalation phase of elapsed breaths and identifying instances where the trajectory of either F or P aw transiently reverses direction during said exhalation phase, thereby detecting transients; selecting two or more points within the exhalation phase that are at preselected distances away from identified transients, calculating the value of K v required to force the values of Signal calculated at said selected points in elapsed breaths to be substantially equal when said selected value of K F is used as the flow coefficient; wherein said generated Signal is either displayed on a screen to serve the purpose of monitoring patient efforts and/or is used to control the output of the ventilator.