COMPUTER CONTROL OF THE INFUSION OF VASOACTIVE DRUGS

In the Cardiac Surgical Intensive Care Unit (CICU) of the University of Alabama Hospital in Birmingham, Alabama, the mean arterial pressure (MAP) is regulated by computer controlled infusion of vasodilating agents and has been performed in 1100 hypertensive patients following open heart surgery. The MAP controller was developed based on investigation of the dynamics of the physiological responses of hypertensive patients to trimethaphan camsylate (Arfonad) and sodium nitroprusside (Nipride). Representative responses were selected for investigation by digital simulation of a computer programmed version of a proportional-integral-derivative (PID) controller algorithm. The PID controller parameters were tuned to elicit a response with acceptable settling time and minimal overshoot during the time course of the simulated MAP. Eight digitally controlled infusion pumps interfaced with the computer based CICU system are used to regulate the blood pressure of patients following cardiac surgery.