Pre-treatment with morphine does not prevent the development of remifentanil-induced hyperalgesia

Purpose: Remifentanil, an ultra short-acting opioid commonly used to supplement general anesthesia, is associated with the development of hyperalgesia that manifests clinically as an increase in postoperative analgesic requirement. This study involving adolescents undergoing scoliosis surgery evaluated whether pre-treatment with morphine prior to commencing remifentanil infusion would decrease the initial 24-hr morphine consumption and pain scores. Methods: Forty ASA I-II pediatric patients undergoing surgical correction of idiopathic scoliosis were recruited in a prospective, randomized, double-blind fashion to receive 150 mu g.kg(-1) morphine or an equal volume saline prior to commencing remifentanil by infusion. The primary outcome was the initial 24hr postoperative morphine consumption. Numeric rating scale (NRS) pain scores at rest and on coughing were recorded, as were scores for nausea, vomiting, and sedation and incidences of pruritus. Results: The groups were demographically similar. No differences were observed between groups vis-a-vis the initial 24-hr morphine consumption, NRS pain scores, sedation, nausea, or vomiting. Conclusion: Pre-treatment with 150 mu g-kg(-1) morphine did not decrease the initial 24-hr morphine consumption in adolescents who received remifentanil by infusion for surgical correction of idiopathic scoliosis.