title: Influence of nociceptive stimulation on analgesia nociception index (ANI) during propofol-remifentanil anaesthesia.
abstract: BACKGROUND
  Measurement of the balance between nociception and anti-nociception during anaesthesia is challenging and not yet clinically established. The Surgical pleth index (SPI), derived from photoplethysmography, was proposed as a surrogate measure of nociception. Recently, the analgesia nociception index (ANI) derived by heart rate (HR) variability was developed. The aim of the present study was to challenge the ability of ANI compared with SPI to detect standardized noxious stimulation during propofol-remifentanil anaesthesia.
  
  
  METHODS
  After Ethics approval and informed consent, 25 patients were anaesthetized with propofol [bispectral index (BIS) 30-60]. A laryngeal mask (LMA) was inserted and remifentanil stepwise increased to effect-site concentrations (Ce(remi)) of 0, 2, and 4 ng ml(-1). At each step, tetanic stimulation (STIM) was applied. ANI, SPI, BIS, HR, and mean arterial pressure (MAP) were obtained before and after LMA insertion and each STIM. Analysis was performed using Wilcoxon rank tests and calculation of prediction probabilities (P(K)).
  
  
  RESULTS
  ANI and SPI, but not BIS, HR, or MAP, were significantly (P<0.05) changed at all examined steps. ANI response to STIM was (median [IQR]) -24 [-12-35], -30 [-20 - -40] and -13 [-5 - -27] at 0, 2 and 4 ng ml(-1) Ce(remi). However, prediction of movement to STIM was not better than by chance, as P(K) values were 0.41 (0.08) for ANI and 0.62 (0.08) for SPI.
  
  
  CONCLUSIONS
  The two variables, ANI and SPI, enabled consistent reflection of stimulation during propofol-remifentanil anaesthesia. Nevertheless, ANI and SPI may improve detection but not prediction of a possible inadequate nociception-anti-nociception balance. Clinicaltrials.gov Identifier. NCT01522508.
authors.affiliation: Department of Anaesthesiology and Intensive Care Medicine, University Hospital Schleswig Holstein Campus Kiel, Schwanenweg 21, D-24105 Kiel, Germany. matthias.gruenewald@uksh.de
authors.forename: M
authors.initials: M
authors.lastname: Gruenewald
authors.forename: C
authors.initials: C
authors.lastname: Ilies
authors.forename: J
authors.initials: J
authors.lastname: Herz
authors.forename: T
authors.initials: T
authors.lastname: Schoenherr
authors.forename: A
authors.initials: A
authors.lastname: Fudickar
authors.forename: J
authors.initials: J
authors.lastname: Höcker
authors.forename: B
authors.initials: B
authors.lastname: Bein
mesh_terms: D000328:Adult; D000368:Aged; D000698:Analgesia; D000758:Anesthesia; D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D059225:Nociception / Q000502:physiology*; D010880:Piperidines / Q000008:administration & dosage*; D015742:Propofol / Q000008:administration & dosage*; D011446:Prospective Studies; D000077208:Remifentanil
chemical_list: D018686:Anesthetics, Intravenous; D010880:Piperidines; D000077208:Remifentanil; D015742:Propofol
keywords: TIVA; analgesia; equipment, monitors; monitoring, depth of anaesthesia; monitoring, respiratory sinus arrhythmia