title: The influence of timing of systemic ketamine administration on postoperative morphine consumption.
abstract: OBJECTIVE
  To determine the influence of timing of systemic ketamine administration on postoperative morphine consumption.
  
  
  METHODS
  Prospective randomized study.
  
  
  METHODS
  Operating rooms, postanesthesia care unit, and gynecology service of a university hospital.
  
  
  METHODS
  Forty-five patients undergoing laparotomy for benign gynecologic pathologies were randomized into 3 groups.
  
  
  METHODS
  In 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.
  
  
  RESULTS
  First 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).
  
  
  CONCLUSIONS
  Lower 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.
authors.affiliation: Department of Anesthesiology, Faculty of Medicine, Uludağ University, Bursa 16059, Turkey. hbilgin@uludag.edu.tr
authors.forename: Hülya
authors.initials: H
authors.lastname: Bilgin
authors.forename: Berin
authors.initials: B
authors.lastname: Ozcan
authors.forename: Tufan
authors.initials: T
authors.lastname: Bilgin
authors.forename: Beklen
authors.initials: B
authors.lastname: Kerimoğlu
authors.forename: Nesimi
authors.initials: N
authors.lastname: Uçkunkaya
authors.forename: Abit
authors.initials: A
authors.lastname: Toker
authors.forename: Tijen
authors.initials: T
authors.lastname: Alev
authors.forename: Selcan
authors.initials: S
authors.lastname: Osma
mesh_terms: D000328:Adult; D016058:Analgesia, Patient-Controlled / Q000379:methods; D000700:Analgesics / Q000008:administration & dosage* / Q000494:pharmacology; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D013509:Gynecologic Surgical Procedures / Q000379:methods; D006801:Humans; D007649:Ketamine / Q000008:administration & dosage* / Q000494:pharmacology; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage*; D010147:Pain Measurement; D010149:Postoperative Pain / Q000517:prevention & control*; D011446:Prospective Studies; D012965:Sodium Chloride / Q000008:administration & dosage; D013997:Time Factors
chemical_list: D000700:Analgesics; D000701:Analgesics, Opioid; D012965:Sodium Chloride; D007649:Ketamine; D009020:Morphine