• Hülya Bilgin, Berin Ozcan, Tufan Bilgin, Beklen Kerimoğlu, Nesimi Uçkunkaya, Abit Toker, Tijen Alev, and Selcan Osma.
• Department of Anesthesiology, Faculty of Medicine, Uludağ University, Bursa 16059, Turkey. hbilgin@uludag.edu.tr
• J Clin Anesth. 2005 Dec 1;17(8):592-7.

Study ObjectiveTo determine the influence of timing of systemic ketamine administration on postoperative morphine consumption.DesignProspective randomized study.SettingOperating rooms, postanesthesia care unit, and gynecology service of a university hospital.PatientsForty-five patients undergoing laparotomy for benign gynecologic pathologies were randomized into 3 groups.InterventionsIn Group 1, before surgical incision, patients received 0.5 mg/kg ketamine IV, followed by normal saline infusion and normal saline IV at wound closure in group 1 (n = 15). In group 2 (n = 15), patients received 0.5 mg/kg ketamine IV before surgery, followed by ketamine infusion 600 mug . kg(-1) . h(-1), until wound closure and normal saline IV at that time. In the other group (group 3, n = 15), patients received normal saline IV before surgery, followed by saline infusion and then 0.5 mg/kg ketamine IV at wound closure. In the postoperative period, patient-controlled analgesia IV morphine was used for postoperative pain relief. First requested analgesic medication time was recorded. Postoperative pain was assessed by measuring morphine consumption at 0 to 2, 0 to 4, and 0 to 24 hours and visual analog scale (VAS) pain scores in response to cough at 2nd, 4th, and 24th hours and during rest at 0 to 2, 0 to 4, and 0 to 24 hours after surgery.Measurement And Main ResultsFirst requested analgesia was shorter in group 1 than the others (P < .01). Mean VAS pain scores in response to cough at 24th hour in groups 2 and 3 were significantly lower than in group 1 (P < .001 and P < .01, respectively). Mean VAS pain scores during rest at 0 to 24 hours in groups 2 and 3 were significantly lower than in group 1 (P < .01 and P < .05, respectively). Morphine consumption was lower in groups 2 and 3 at 0 to 2 hours (P < .001 and P < .01). Moreover, morphine consumption at 0 to 4 hours in group 2 was significantly lower (P < .01).ConclusionsLower pain scores and morphine consumption in groups 2 and 3 may be related to higher plasma ketamine concentrations caused by the higher doses and later administration. Our findings suggest that a single preoperative dose of ketamine provided less analgesia compared with other dosing regimens that included intraoperative infusions or postoperative administration.

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