ARTERIAL CO2 MONITOR AND CLOSED LOOP CONTROLLER

摘要

The arterial CO2 monitor and closed loop controller for use with a ventilator mo nitors a patient's breath and determines PaCO2 based upon a determination of a deadspace ratio, which is the r atio of the alveolar deadspace to alveolar tidal volume. The method generally comprises the steps of continuously monitoring meas urable parameter of a patient's breath; obtaining an input value of PaCO2 from a blood sample of the patient and using t he patient's breath parameters and the input value to calculate the deadspace ratio; and continuously determining PaCO2 based on the assumption that the dead-space ratio subsequently remains constant. Decision rules obtained from oth er measurable data are preferably also used to identify the onset of changes in the deadspace ratio, and a new deadspace ratio is then determined from the patient's breath parameters and further input value of PaCO2 from the patient's blood sample.