Patent ID: 7527054

Claim:
A method of operating a ventilator to control the fraction of pressure inspired oxygen (FiO 2 ), the method comprising: providing a pulse oximeter to measure a patient's pulse oximetry; providing a FiO 2 flow rate controller, wherein the flow rate controller controls the flow rate of FiO 2 to the patient; measuring the patient's pulse oximetry and providing a measured pulse oximetry value; averaging the patient's measured pulse oximetry value over a period of time; providing a ventilator controller responsive to the average of the patient's measured pulse oximetry value, wherein the FiO 2 flow rate controller is responsive to the ventilator controller and controls the flow rate of FiO 2 to the patient; selecting the time period for averaging the patient's measured pulse oximetry value; selecting a first, a second, and a third pulse oximetry level as set points for the ventilator controller; selecting an FiO 2 operating range having a low end, a high end and a mid-point, wherein the midpoint of the range is equal to one-half the sum of the low end and the high end; selecting a first incremental amount for decreasing the flow rate of FiO 2 and a second incremental amount for increasing the flow rate of FiO 2 ; selecting an update time interval, wherein the update time interval is the interval of time between comparisons by the ventilator controller of the set points and the averaged measured pulse oximetry value of the patient; setting the FiO 2 flow rate controller at a flow rate equal to the mid-point of the operating range; decreasing the flow rate of FiO 2 by the first incremental amount when the average pulse oximetry value is greater than the first level; increasing the flow rate of FiO 2 by the second incremental amount when the average pulse oximetry value is less than the second level; and increasing the flow rate of FiO 2 to a maximum rate when the average pulse oximetry value is less than the third level.