title: Perioperative small-dose S(+)-ketamine has no incremental beneficial effects on postoperative pain when standard-practice opioid infusions are used.
abstract: Several studies report that when small-dose racemic ketamine, an N-methyl-D-aspartate receptor antagonist, is administered perioperatively, opioid consumption is reduced postoperatively. S(+)-ketamine has a higher affinity for the N-methyl-D-aspartate receptor and less-serious side effects than racemic ketamine. Thirty patients scheduled for elective arthroscopic anterior cruciate ligament repair were enrolled in this randomized, double-blinded clinical trial designed to determine the preemptive effect of S(+)-ketamine on postoperative analgesia requirements in a setting of clinically relevant perioperative analgesia. Total IV anesthesia was induced and maintained with remifentanil (0.125-1.0 microg x kg(-1) x min(-1)) and a propofol target-controlled infusion (target 2-4 microg/mL). The Ketamine group received a bolus of 0.5 mg/kg S(+)-ketamine before incision, followed by a continuing infusion of 2 microg x kg(-1) x min(-1) until 2 h after emergence from anesthesia. The Control group received NaCl in the same sequence. After IV morphine provided pain relief down to < or =3 on a visual analog scale scored from 0 to 10, patients were connected to a patient-controlled analgesia device. There were no significant differences between the two groups in terms of total morphine consumption or VAS scores, either at rest or with movement. In our study, S(+)-ketamine did not contribute to postoperative pain reduction, possibly because of the clinically routine perioperative opioid analgesia.
  
  
  CONCLUSIONS
  Small-dose S(+)-ketamine had no positive effect on postoperative analgesia when administered perioperatively for elective arthroscopic anterior cruciate ligament repair. Unlike investigations of the racemic mixture of ketamine, our study methods included timely standard-practice perioperative opioid analgesia, which seems to make supplemental analgesia unnecessary.
authors.affiliation: Department of Anesthesiology and Intensive Care Medicine, Ludwig Boltzmann Institute of Experimental Anesthesiology and Research in Intensive Care Medicine, Wilhelminenspital, Vienna, Austria. wolfgang.jaksch@chello.at
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Jaksch
authors.forename: Stefan
authors.initials: S
authors.lastname: Lang
authors.forename: Robert
authors.initials: R
authors.lastname: Reichhalter
authors.forename: Gerald
authors.initials: G
authors.lastname: Raab
authors.forename: Klaus
authors.initials: K
authors.lastname: Dann
authors.forename: Sylvia
authors.initials: S
authors.lastname: Fitzal
mesh_terms: D000328:Adult; D016058:Analgesia, Patient-Controlled; D000700:Analgesics / Q000008:administration & dosage* / Q000009:adverse effects; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000009:adverse effects; D016118:Anterior Cruciate Ligament / Q000601:surgery; D001182:Arthroscopy; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D007275:Injections, Intravenous; D007649:Ketamine / Q000008:administration & dosage* / Q000009:adverse effects; D008297:Male; D009020:Morphine / Q000008:administration & dosage* / Q000009:adverse effects; D010147:Pain Measurement; D010149:Postoperative Pain / Q000188:drug therapy / Q000517:prevention & control*; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors
chemical_list: D000700:Analgesics; D000701:Analgesics, Opioid; D016194:Receptors, N-Methyl-D-Aspartate; D007649:Ketamine; D009020:Morphine