Automation of measurements and interventions in the systematic care of postoperative cardiac surgical patients.

Since July of 1967, a computer-based system has been employed in the observation and treatment of 8500 patients following cardiac surgical procedures. Of the 12 beds in the University of Alabama Hospital Cardiac Surgical Intensive Care Unit, 10 are equipped with biomedical instrumentation interfaced with digital computer systems. These systems perform the automatic acquisition, display, storage, retrieval, and charting of measurements; computation and evaluation of acid-base balance from manually entered blood gas data; analysis of the data for the detection and treatment of impaired cardiac performance; automatic control of blood infusion and vasodilating agents by closed-loop feedback control techniques; hourly evaluation of chest tube drainage patterns to detect excessive blood loss in the early hours following operation; and computation of the infusion rate (ml/hr) of pharmacologic agents according to a specified dosage (microgram/kg/min). Automatic control of left atrial pressure by blood infusion has been applied to 8000 patients during the past 10 years. Regulation of mean arterial pressure by computer-controlled infusion of vasodilating agents has been performed in 400 patients in the last 2 years. The use of the system has contributed to the reduction of patient time spent in the unit to 24 hours or less for the majority of the patients.