Real-time fuzzy control of mean arterial pressure in postsurgical patients in an intensive care unit

The authors have developed a fuzzy control system to provide closed-loop control of mean arterial pressure (MAP) in postsurgical patients in a cardiac surgical intensive care unit setting, by regulating sodium nitroprusside infusion. The core of the control algorithms is a nonlinear proportional-integral (PI) controller, which precisely represents the simplest fuzzy controller. The proportional-gain and integral-gain are adjusted continuously according to the error and rate change of the error of MAP. Twelve postoperative patients who exhibited elevated MAP following coronary artery bypass grafting procedures took part in the study. The length of time that twelve patients were on the fuzzy control system ranged from 1 h 45 min to 18 h 7 min. The total fuzzy-controller run time was 95 h 13 min. Clinical results showed that the average percentage of time in which MAP stayed between 90% and 110% of the MAP setpoint was 89.31%, with a standard deviation of 4.96%