Closed-loop control of propofol anaesthesia using bispectral index: performance assessment in patients receiving computer-controlled propofol and manually controlled remifentanil infusions for minor surgery.

BACKGROUND In a previous study we used the bispectral index (BIS) for automatic control of propofol anaesthesia, using a proportional-integral-differential control algorithm. As control was less than optimal in some patients, we revised the constants of the control algorithm. The aim of the current study was to measure the performance of the revised system in patients undergoing minor surgery under propofol and remifentanil anaesthesia. METHODS Twenty adult patients scheduled for body surface surgery were enrolled. Anaesthesia was manually induced with target-controlled infusions (TCI) of propofol and remifentanil. After the start of surgery, when anaesthesia was clinically adequate, automatic control of the propofol TCI was commenced using the revised closed-loop system. For patients 11-20, effect-site steering was also incorporated into the closed-loop control algorithm. Adequacy of anaesthesia during closed-loop control was assessed clinically, and by calculating the median performance error (MDPE), the median absolute performance error (MDAPE) and the mean offset of the control variable. RESULTS The system provided adequate operating conditions and stable cardiovascular values in all patients during closed-loop control. The mean MDPE and MDAPE were -0.42% and 5.63%, respectively. Mean offset of the BIS from setpoint was -0.2. No patients reported awareness or recall of intraoperative events. CONCLUSIONS The system was able to provide clinically adequate anaesthesia in all patients, with better accuracy of control than in the previous study. There was a tendency for more accurate control in those patients in whom the control algorithm incorporated effect-site steering.

[1]  K. Olkkola,et al.  Performance assessment of an adaptive model-based feedback controller: Comparison between atracurium, mivacurium, rocuronium and vecuronium , 1996, International journal of clinical monitoring and computing.

[2]  K. Ikeda,et al.  Electroencephalographic Derivatives as a Tool for Predicting the Depth of Sedation and Anesthesia Induced by Sevoflurane , 1998, Anesthesiology.

[3]  E Konecny,et al.  Middle latency auditory evoked responses and electroencephalographic derived variables do not predict movement to noxious stimulation during 1 minimum alveolar anesthetic concentration isoflurane/nitrous oxide anesthesia. , 1999, Anesthesia and analgesia.

[4]  G N Kenny,et al.  Closed-loop control of propofol anaesthesia. , 1999, British journal of anaesthesia.

[5]  M. Doi,et al.  Prediction of movement at laryngeal mask airway insertion: comparison of auditory evoked potential index, bispectral index, spectral edge frequency and median frequency. , 1999, British journal of anaesthesia.

[6]  T. Short,et al.  Closed loop control of anaesthesia: an assessment of the bispectral index as the target of control , 2000, Anaesthesia.

[7]  G N Kenny,et al.  Auditory Evoked Potential Index Predicts the Depth of Sedation and Movement in Response to Skin Incision during Sevoflurane Anesthesia , 2001, Anesthesiology.

[8]  M. Struys,et al.  Comparison of Closed-loop Controlled Administration of Propofol Using Bispectral Index as the Controlled Variable versus “Standard Practice” Controlled Administration , 2001, Anesthesiology.

[9]  K. Leslie,et al.  Closed loop control of sedation for colonoscopy using the Bispectral Index* , 2002, Anaesthesia.

[10]  A. Absalom,et al.  Closed-loop Control of Anesthesia Using Bispectral Index: Performance Assessment in Patients Undergoing Major Orthopedic Surgery under Combined General and Regional Anesthesia , 2002, Anesthesiology.

[11]  Steven L. Shafer,et al.  Measuring the predictive performance of computer-controlled infusion pumps , 1992, Journal of Pharmacokinetics and Biopharmaceutics.