Patent ID: 6557553
Filing Date: 2003-05-06
Classification: A61M

Abstract:
In a method for determining real time estimates of patient airway resistance, patient lung compliance, and connecting tube circuit compliance, in a ventilator system providing gas at a desired pressure to a patient airway and lungs through a connecting tube circuit during pressure based ventilation, the method comprising the steps of:measuring the flow of gas to the connecting tube circuit; measuring the pressure of gas within the connecting tube circuit; determining a real time estimate of patient airway resistance based upon the flow of gas to the connecting tube circuit and the pressure of gas within the connecting tube circuit; determining a real time estimate of patient lung compliance based upon the flow of gas to the connecting tube circuit and the pressure of gas within the connecting tube circuit; determining a real time estimate of the connecting tube circuit compliance based upon the flow of gas to the connecting tube circuit and the pressure of gas within the connecting tube circuit; and determining an estimate of the flow into the patient lungs from the estimates of the patient airway resistance, the patient lung compliance, and the connecting tube circuit compliance, by discretizing the following equation: QL&it;(s)=1R^&it;C^Ts+C^L+C^TR^&it;C^L&it;C^T&CenterDot;QV&it;(s)where QL is the flow into the patient lungs, R is the patient airway resistance, CL is the patient lung compliance, and CT is the connecting tube circuit compliance.