[Computer-assisted regulation of blood pressure by drugs acting on the cardiovascular system. Problems in the development of a closed-loop control system].

This article reports on the problems associated with the development and use of a computer programme for computer-monitored blood pressure control by means of cardio- and/or vasoactive drugs. The computer, a monitoring device routinely used in hospitals, and an infusion pump on the one hand, and the patient on the other, are part of a closed loop control system. Regulation is effected in the manner practised in hospitals, the mean arterial pressure (MAP) serving as an auxiliary controlled variable. The computer programme analyses the directly measured blood pressure curve in two respects: Detection and assessment of external disturbing factors and endogenously conditioned changes in the blood pressure curve and determination of MAP via a special control algorithm. With the help of a prototype of the automatic controller, the programme was subjected to extensive clinical trials in more than 140 patients to date. The programme was particularly successful wherever a residual circadian rhythm leads to variable requirements of vasopressor or cardiovascular drugs. The use of technical control algorithms has proved unsuitable because of the complex nature of blood pressure control.