title: Analgesic effects of caudal and intramuscular S(+)-ketamine in children.
abstract: BACKGROUND
  Previous studies suggest that caudal administration of ketamine cause effective analgesia. The purpose of the current study was to compare the clinical effectiveness and plasma concentrations of S(+)-ketamine after caudal or intramuscular administration in children to distinguish between local and systemic analgesia.
  
  
  METHODS
  After induction of general anesthesia, 42 patients, aged 1 to 7 yr, scheduled to undergo inguinal hernia repair randomly received a caudal (caudal group) or intramuscular (intramuscular group) injection of 1 mg/kg S(+)-ketamine. Intraoperatively, heart rate (HR), mean arterial pressure (MAP) and arterial oxygen saturation were measured. Postoperative measurements included duration of analgesia, a four-point sedation score, and hemodynamic and respiratory monitoring for 6 h in the recovery room. Analgesic requirements in the recovery room were assessed by an independent blinded observer using an observational pain/discomfort scale (OPS). Plasma samples for determination of ketamine concentrations were obtained before and 10, 20, 30, 45, 60, 90, 120, and 180 min after injection of S(+)-ketamine.
  
  
  RESULTS
  A significantly longer duration of analgesia (P < 0.001) was observed after caudal administration (528 min [220-1,440 min]; median [range]) when compared with intramuscular administration (108 min [62-1,440 min]) of S(+)-ketamine. Plasma levels of ketamine were significantly lower from 10 to 45 min after caudal administration than after intramuscular injection.
  
  
  CONCLUSIONS
  Caudal S(+)-ketamine provides good intra- and postoperative analgesia in children. Despite similar plasma concentrations during most of the postoperative observation period, caudal S(+)-ketamine provided more effective analgesia than did intramuscular S(+)-ketamine, indicating a local analgesic effect.
authors.affiliation: Departments of Anesthesiology and Intensive Care and Pharmacology, University of Vienna, Vienna, Austria. Herbert.Koinig@unvie.ac.at
authors.forename: H
authors.initials: H
authors.lastname: Koinig
authors.forename: P
authors.initials: P
authors.lastname: Marhofer
authors.forename: C G
authors.initials: CG
authors.lastname: Krenn
authors.forename: W
authors.initials: W
authors.lastname: Klimscha
authors.forename: E
authors.initials: E
authors.lastname: Wildling
authors.forename: W
authors.initials: W
authors.lastname: Erlacher
authors.forename: A
authors.initials: A
authors.lastname: Nikolic
authors.forename: K
authors.initials: K
authors.lastname: Turnheim
authors.forename: M
authors.initials: M
authors.lastname: Semsroth
mesh_terms: D000042:Absorption; D000698:Analgesia / Q000379:methods; D015360:Analgesia, Epidural / Q000379:methods; D000700:Analgesics / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics; D001794:Blood Pressure / Q000187:drug effects; D002648:Child; D002675:Child, Preschool; D004311:Double-Blind Method; D006339:Heart Rate / Q000187:drug effects; D006552:Hernia, Inguinal / Q000601:surgery; D006801:Humans; D007223:Infant; D007268:Injections, Epidural; D007273:Injections, Intramuscular; D007649:Ketamine / Q000008:administration & dosage* / Q000097:blood / Q000493:pharmacokinetics; D010100:Oxygen / Q000097:blood; D010149:Postoperative Pain / Q000517:prevention & control; D011446:Prospective Studies
chemical_list: D000700:Analgesics; D007649:Ketamine; D010100:Oxygen