Closed-loop control of oxygen delivery during aeromedical evacuation of patients

A prototype oxygen delivery system was developed and tested. It controls oxygen and air delivery in order to regulate arterial oxygen saturation (SaO/sub 2/) and breathing circuit volume, thereby protecting patients from hypoxemia while minimizing the use of oxygen. Three discrete-time, digital control loops make up the system. The primary controller regulates the SaO/sub 2/ through a proportional controller to adjust the setpoint circuit oxygen concentration. The other two control loops regulate the circuit oxygen concentration and volume. The system was tested on four healthy human volunteers in a hypobaric chamber. Two trials were conducted with each volunteer. The servo-controlled oxygen delivery system successfully regulated SaO/sub 2/ in each volunteer for both trials. The results of the trials are summarized.<
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