• Thomas Engelhardt, Christian Zaarour, Basem Naser, Carolyne Pehora, Joost de Ruiter, Andrew Howard, and Mark W Crawford.
• Department of Anesthesia, The Hospital for Sick Children, University of Toronto, 555 University Ave., Toronto, Ontario, Canada M5G 1X8.
• Anesth. Analg. 2008 Oct 1;107(4):1170-5.

BackgroundRemifentanil-based anesthesia is commonly used to facilitate neurophysiologic monitoring during pediatric scoliosis surgery. Acute opioid tolerance and/or hyperalgesia resulting from remifentanil-based anesthesia may involve activation of N-methyl-D-aspartate systems. We hypothesized that low-dose intraoperative infusion of the N-methyl-d-aspartate antagonist ketamine would suppress the development of tolerance and thereby decrease postoperative morphine consumption in children receiving remifentanil-based anesthesia for scoliosis surgery.MethodsThirty-four adolescents aged 12-18 yr scheduled for scoliosis surgery were randomly assigned to receive intraoperative low-dose ketamine (bolus dose of 0.5 mg/kg followed by continuous infusion of 4 microg.kg(-1).min(-1)) or an equal volume of saline during propofol/remifentanil anesthesia. Cumulative morphine consumption was assessed using a patient-controlled analgesia device for 72 h after surgery. Postoperative morphine consumption, pain scores at rest and during cough, and sedation scores were recorded by a blinded investigator every hour for the first 4 h, every 4 hours for 20 h, and then every 12 hours for 72 h.ResultsCumulative morphine consumption at 24, 48, and 72 h after surgery did not differ significantly between groups (ketamine group: 1.57+/-0.56, 3.05+/-1.14, and 4.46+/-1.53 mg/kg; saline group: 1.60+/-0.53, 2.87+/-1.05, and 4.11+/-1.71 mg/kg, respectively). No differences in pain or sedation scores were found. The duration of anesthesia was similar in the two groups.ConclusionsThese data do not support the use of intraoperative low-dose ketamine to prevent the development of remifentanil-induced acute opioid tolerance and/or hyperalgesia during pediatric scoliosis surgery.

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