An observational trial of a computerized drug delivery system on two patients

A computerized drug delivery system has been designed and tested for automatic regulation of mean arterial blood pressure (MAP) of human patients by infusion of a vasodilator (sodium nitroprusside). Its control algorithm belongs to a type of long-range predictive control with a combination of finite-horizon and an infinite horizon optimization terms. The controller operates in an adaptive mode by using a recursive control-relevant identification algorithm for long-range predictive control. A limited pilot study using the system to perform closed-loop regulation of MAP in two patients undergoing coronary artery bypass surgery was performed. At all times the drug infusion was monitored by an expert supervisor who was immediately available to adjust/terminate the infusion if indicated. The trial results show that without human intervention, patients´ MAP was kept within ±10 mmHg of the setpoint for more than 70% of the time even in the presence of significant natural and unmeasurable disturbances. Further improvement to the overall control system such as adding supervisory control is needed