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Clinical evaluation of an automatic blood pressure controller during cardiac surgery
R H Meijers1, D Schmartz, F R Cantraine
1Department of Computer Science, Faculty of Medicine, Free University of Brussels (ULB), Belgium. rmeijers@ulb.ac.be
Objective:
During surgery, computers can be of great use to support the anesthesiologist in providing task automation. In this paper we describe a closed loop blood pressure controller and show the results of its clinical evaluation.
Methods:
The controller is based on a simple and robust Proportional-Integral controller and a supervising, rule based, expert system. Adaptive control is necessary because the sensitivity of the patients to sodium nitroprusside varies over a wide range. Thirty-three clinical tests during cardiac surgery, including the cardiopulmonary bypass phase, were performed.
Results:
On average the controller was in automatic mode for 90.6 +/- 9.6% of the time. The performance during automatic control showed the mean arterial pressure to be within 10 mmHg of the setpoint for 71.4 +/- 15.5% of the time. The average absolute distance to the setpoint was 8.1 +/- 7.2 mmHg.
Conclusions:
The overall performance of the controller was noted as very satisfactory by the anesthesiologists.