ARTERIAL CO2 MONITOR AND CLOSED LOOP CONTROLLER

摘要

The arterial CO2 monitor and closed loop controller for use with a ventilator monitors a patient's breath anddetermines PaCO2 based upon a determination of a deadspace ratio, which is the ratio of the alveolar deadspace to alveolar tidalvolume. The method generally comprises the steps of continuously monitoring measurable parameter of a patient's breath;obtaining an input value of PaCO2 from a blood sample of the patient and using the patient's breath parameters and theinput value to calculate the deadspace ratio; and continuously determining PaCO2 based on the assumption that thedead-space ratio subsequently remains constant. Decision rules obtained from other measurable data are preferably also used toidentify the onset of changes in the deadspace ratio, and a new deadspace ratio is then determined from the patient's breathparameters and further input value of PaCO2 from the patient's blood sample.