title: Novel multiparameter approach for measurement of nociception at skin incision during general anaesthesia.
abstract: BACKGROUND
  Direct indicators for the evaluation of the nociceptive-anti-nociceptive balance during general anaesthesia do not exist. The aim of this study was to combine physiological parameters to obtain such an indicator.
  
  
  METHODS
  Fifty-five females scheduled for surgery under general anaesthesia combining target-controlled infusions of propofol and remifentanil were studied. Propofol was given to maintain state entropy (SE) at 50 and remifentanil was targeted at 1, 3 or 5 ng ml(-1). The patients' reactions and clinical signs of nociception, remifentanil levels and estimation of noxious intensity of incision were combined into a clinical score [Clinical Signs-Stimulus-Antinociception (CSSA)] to evaluate the nociceptive-anti-nociceptive balance. ECG, photoplethysmography (PPG), response entropy (RE) and SE were recorded from 60 s before to 120 s after skin incision. Differences between post- and pre-incision values of heart rate variability (HRV), PPG and pulse transition time related parameters were analysed off-line to evidence the best predictors of CSSA. Those best predictors of CSSA served to develop a response index of nociception (RN), scaled from 0 to 100. This index was further tested in 10 additional patients.
  
  
  RESULTS
  HRV, RE, RE-SE and PPG variability were the best predictors of CSSA. The prediction probability of RN at predicting CSSA was 0.78. RN response was higher after larger incision, in movers and with lower remifentanil concentrations.
  
  
  CONCLUSIONS
  The empirically developed algorithm of RN leads to an index that seems to adequately estimate the nociceptive-anti-nociceptive balance at skin incision during general anaesthesia. In the future, CSSA may serve as a reference for studies investigating methods aimed at evaluating this pharmacodynamic component of anaesthesia.
authors.affiliation: Department of Anaesthesia, Tampere University Hospital, PO Box 2000, FIN-33521 Tampere, Finland.
authors.forename: M
authors.initials: M
authors.lastname: Rantanen
authors.forename: A
authors.initials: A
authors.lastname: Yli-Hankala
authors.forename: M
authors.initials: M
authors.lastname: van Gils
authors.forename: H
authors.initials: H
authors.lastname: Yppärilä-Wolters
authors.forename: P
authors.initials: P
authors.lastname: Takala
authors.forename: M
authors.initials: M
authors.lastname: Huiku
authors.forename: M
authors.initials: M
authors.lastname: Kymäläinen
authors.forename: E
authors.initials: E
authors.lastname: Seitsonen
authors.forename: I
authors.initials: I
authors.lastname: Korhonen
mesh_terms: D000328:Adult; D000368:Aged; D000465:Algorithms; D000768:Anesthesia, General / Q000379:methods*; D019162:Anesthetics, Combined; D018686:Anesthetics, Intravenous; D062109:Dermatologic Surgical Procedures; D004562:Electrocardiography / Q000187:drug effects; D004569:Electroencephalography / Q000187:drug effects; D019277:Entropy; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007262:Infusions, Intravenous; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D010147:Pain Measurement / Q000379:methods; D017156:Photoplethysmography; D010880:Piperidines; D015742:Propofol; D000077208:Remifentanil; D012815:Signal Processing, Computer-Assisted
chemical_list: D019162:Anesthetics, Combined; D018686:Anesthetics, Intravenous; D010880:Piperidines; D000077208:Remifentanil; D015742:Propofol