title: Clinical evaluation of an automatic blood pressure controller during cardiac surgery.
abstract: 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.
authors.affiliation: Department of Computer Science, Faculty of Medicine, Free University of Brussels (ULB), Belgium. rmeijers@ulb.ac.be
authors.forename: R H
authors.initials: RH
authors.lastname: Meijers
authors.forename: D
authors.initials: D
authors.lastname: Schmartz
authors.forename: F R
authors.initials: FR
authors.lastname: Cantraine
authors.forename: L
authors.initials: L
authors.lastname: Barvais
authors.forename: A A
authors.initials: AA
authors.lastname: d'Hollander
authors.forename: J A
authors.initials: JA
authors.lastname: Blom
mesh_terms: D000465:Algorithms; D000703:Analog-Digital Conversion; D001021:Aortic Valve / Q000601:surgery; D001331:Automation; D001794:Blood Pressure / Q000187:drug effects; D015924:Blood Pressure Monitors; D006348:Cardiac Surgical Procedures / Q000295:instrumentation; D002315:Cardiopulmonary Bypass; D003199:Computer Systems; D001026:Coronary Artery Bypass; D004867:Equipment Design; D005069:Evaluation Studies as Topic; D005103:Expert Systems; D005260:Female; D018056:Hemorheology; D006801:Humans; D007260:Infusion Pumps; D008297:Male; D008943:Mitral Valve / Q000601:surgery; D016343:Monitoring, Intraoperative / Q000295:instrumentation*; D009599:Nitroprusside / Q000008:administration & dosage / Q000627:therapeutic use; D012815:Signal Processing, Computer-Assisted; D012984:Software; D014665:Vasodilator Agents / Q000008:administration & dosage / Q000627:therapeutic use
chemical_list: D014665:Vasodilator Agents; D009599:Nitroprusside