title: Randomized controlled trial of the effect of depth of anaesthesia on postoperative pain.
abstract: BACKGROUND
  Our hypothesis was that deep anaesthesia, as estimated by a low target bispectral index (BIS) of 30-40, would result in less postoperative pain than that achieved at a conventional depth of anaesthesia.
  
  
  METHODS
  We undertook a randomized double-blind controlled study at two tertiary teaching hospitals in New Zealand (2010-1) recruiting 135 adult patients ASA I-II presenting for non-emergent surgery under general anaesthesia requiring tracheal intubation. Anaesthesia was maintained with desflurane and a multimodal analgesia regimen comprising fentanyl infusion, i.v. paracetamol, and parecoxib. Patients were randomly assigned to either a low BIS (30-40) group or a high BIS (45-60) group. Desflurane concentrations were titrated to achieve these targets. Postoperative pain was assessed by: the pain on awakening (0-10, verbal rating scale, VRS(awake)) in the post-anaesthetic care unit; pain on activity at 20-24 h after operation (VRS(d1A)); and the rate of morphine patient-controlled analgesia (PCA) usage over the first 24 h.
  
  
  RESULTS
  There was no statistically significant difference between the two groups for any of the pain scores. The median [inter-quartile range (IQR)] VRS(awake) was 4.0 (0-8) for the low and 4.0 (0-8) for the high BIS groups (P=0.56). The median (IQR) VRS(d1A) was 3.0 (1-5) for the low and 3.0 (1.5-4.5) for the high BIS groups (P=0.83). The median PCA morphine consumption in the low BIS group was 0.61 mg h(-1) (0.04-1.5) vs 0.43 mg h(-1) (0-1.59) in the high BIS group (P=0.98).
  
  
  CONCLUSIONS
  We conclude that there is no clinically useful analgesic effect of a deep anaesthesia regimen.
authors: Department of Anaesthesia, Anglesea Hospital, Knox Street Clinic, PO Box 228, Hamilton Waikato 3204, New Zealand.
authors: C J
authors: CJ
authors: Law
authors: G M
authors: GM
authors: Jacobson
authors: M
authors: M
authors: Kluger
authors: M
authors: M
authors: Chaddock
authors: M
authors: M
authors: Scott
authors: J W
authors: JW
authors: Sleigh
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D016058:Analgesia, Patient-Controlled / Q000379:methods; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000097:blood; D000768:Anesthesia, General / Q000379:methods*; D018685:Anesthetics, Inhalation / Q000008:administration & dosage; D000077335:Desflurane; D004311:Double-Blind Method; D004334:Drug Administration Schedule; D004569:Electroencephalography / Q000379:methods; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage / Q000097:blood; D006801:Humans; D007530:Isoflurane / Q000008:administration & dosage / Q000031:analogs & derivatives; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods; D009020:Morphine / Q000008:administration & dosage; D010147:Pain Measurement / Q000379:methods; D010149:Postoperative Pain / Q000517:prevention & control*; D055815:Young Adult
chemical_list: D000701:Analgesics, Opioid; D018685:Anesthetics, Inhalation; D009020:Morphine; D000077335:Desflurane; D007530:Isoflurane; D005283:Fentanyl
keywords: depth of anaesthesia; postoperative pain