title: High-dose remifentanil prevents development of thermal hyperalgesia in a neuropathic pain model.
abstract: BACKGROUND
  Intraoperative nerve lesions can lead to chronic postoperative pain. There are conflicting data as to whether or not anaesthetics administered intraoperatively are beneficial. We investigated if remifentanil administered at the time of nerve injury was able to attenuate neuropathic hypersensitivity.
  
  
  METHODS
  Rats were anaesthetized with isoflurane, endotracheally intubated, and a tail vein catheter was inserted. Rats received an i.v. infusion of either saline or low- or high-dose remifentanil (2 or 20 μg kg(-1) min(-1), respectively) for 20 min. During this time, rats received a spinal nerve L5 transection to induce neuropathic pain or a sham procedure. Behavioural tests to assess mechanical and cold allodynia and heat hyperalgesia were performed on postoperative days 1, 3, 7, 14, 21, and 28.
  
  
  RESULTS
  Sham-operated animals exhibited no hypersensitivity regardless of the intraoperative remifentanil dose. In rats which received spinal nerve L5 transection, mechanical and cold allodynia developed with no significant differences between treatment groups. However, thermal hyperalgesia was reduced in rats given high-dose remifentanil: mean (standard deviation) area under the curve 426 (53) compared with 363 (34) and 342 (24) in saline or low-dose remifentanil treated rats, respectively (P<0.05).
  
  
  CONCLUSIONS
  High-dose remifentanil administered at the time of transection of the spinal nerve at L5 prevents subsequent thermal hyperalgesia.
authors.affiliation: Department of Anaesthesia,  University Hospital Erlangen, Erlangen,  Germany.
authors.forename: N A
authors.initials: NA
authors.lastname: Manering
authors.forename: T
authors.initials: T
authors.lastname: Reuter
authors.forename: H
authors.initials: H
authors.lastname: Ihmsen
authors.forename: D C
authors.initials: DC
authors.lastname: Yeomans
authors.forename: A
authors.initials: A
authors.lastname: Tzabazis
mesh_terms: D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000627:therapeutic use*; D000818:Animals; D019540:Area Under Curve; D001522:Behavior, Animal / Q000187:drug effects; D003080:Cold Temperature; D003627:Data Interpretation, Statistical; D006358:Hot Temperature; D006930:Hyperalgesia / Q000209:etiology* / Q000517:prevention & control*; D008297:Male; D009437:Neuralgia / Q000150:complications*; D010149:Postoperative Pain / Q000188:drug therapy; D010812:Physical Stimulation; D010880:Piperidines / Q000008:administration & dosage / Q000627:therapeutic use*; D051381:Rats; D017207:Rats, Sprague-Dawley; D000077208:Remifentanil; D013127:Spinal Nerves / Q000293:injuries
chemical_list: D000701:Analgesics, Opioid; D010880:Piperidines; D000077208:Remifentanil