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October 14, 2007
2:00 PM - 4:00 PM
Room Hall D, Area M,
Postoperative Pain Intensity Following High Dose Remifentanil with and without Amantadine
Sascha Treskatsch, M.D., Michael Klambeck, M.D., Andreas Kopf, M.D., Michael Schaefer, M.D., Ph.D.
Department of Anesthesiology and Critical Care Medicine, Charite University Berlin, Campus Benjamin Franklin, Berlin, Germany
Objective: Previous clinical studies show increased postoperative pain intensity and cumulative morphine consumption following intraoperative high dose remifentanil. In this study we investigated in patients undergoing lower abdominal surgery i) whether postoperative pain and analgesic consumption is increased following intraoperative high versus low dose remifentanil, and ii) whether this is prevented by preoperative administration of the NMDA antagonist amantadine.

Methods: Following institutional IRB approval and written informed consent patients (n=60) undergoing major abdominal surgery were randomly assigned to three anaesthetic regimens in a double-blind manner: group (RL) received a continuous remifentanil infusion of 0,1 mg/kg/min and sevoflurane titrated to autonomic responses; group (RH) received a continuous inspiratory concentration of sevoflurane (0,5 MAC) and a remifentanil infusion of > 0,1 mg/kg/min titrated to autonomic responses; group (RHA) received the same anaesthetic plan as in group (RH) but 30 min preoperatively 200 mg amantadine iv. Fourty minutes before the end of surgery all patients received a 0.15 mg/kg morphine bolus. Pain intensity was assessed 0-15 min by a 3-point Behavioral pain score (BPS), 15-240 min by a 4-point verbal painrating scale (VRS), and 1-6 h by an 11-point numerical rating scale (NRS). In addition, the time and amount of supplemental patient controlled morphine consumption was recorded.

Results: There were no significant differences in the demographic characteristics of the three groups.Twelve patients had to be excluded according to the protocol. The mean remifentanil infusion was in group RH (n=17) 0,20 ± 0,01 and in group RHA (n=16) 0,22 ± 0,01 mg/ kg/ min which were significantly greater than in group RL (n=15) (P<0.05, RM-ANOVA and post-hoc Scheffe test). At 0-15 min BPS, at 15-240 min VRS, and at 1-6 h NRS pain scores were not significantly different. Kaplan-Meier curves for the time to first postoperative morphine rescue medication and cumulative morphine consumptions (30,7± 4,1 mg group RL, 28,9 ± 5,2 mg group RH and 30,6 ± 2,0 mg group RHA) were not significantly different between groups.

Conclusions: A two-fold higher intraoperative remifentanil concentration did not result in significant differences in postoperative pain intensity and morphine consumption between all groups. Therefore, we could not repeat previously reported increased pain and analgesic consumption postoperatively. However, this may be explained in part by the low pain scores of all patients due to the morphine bolus at the end of surgery and/or by the low number of patients per group due to the drop out rate. Consequently, preoperative amandatin did not show any additional benefit.

Anesthesiology 2007; 107: A895