Adaptive Fuzzy Control of Mean Arterial Pressure in Critically-ill Patients

A fuzzy control sodium nitroprusside delivery system was developed to closed-loop control mean arterial pressure (MAP) in postsurgical patients who exhibited high MAP following coronary artery bypass grafting procedures in a cardiac surgical intensive care unit. The core of the control system was a nonlinear adaptive PI controller, which precisely represented a simplest fuzzy controller. The proportional-gain and integral-gain adjusted continuously according to error and rate change of error of MAP. Twelve patients took part in the study. The length of time that the patients were on the fuzzy control system ranged from 1 hour 45 minutes to 18 hours 7 minutes. The total fuzzy-control-run time was 95 hours 13 minutes. The clinical results was satisfactory, since 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%.