Effects of perioperative intravenous low dose of ketamine on postoperative analgesia in children

Abstract

Low dose of ketamine reduces postoperative pain and opioid consumption in adult studies. However, there are only a few data with controversial results in the paediatric population. The aim of this randomized controlled trial was to evaluate the use of low doses of intravenous ketamine on postoperative pain in children after surgery on the lower part of the body. Thirty-seven children with ASA 1 or 2 from 6 to 60 months of age, undergoing scheduled surgery, were prospectively enrolled in a double blind sequential trial using a triangular test, with analysis every 10 patients treated. The children were randomly assigned to intravenously receive saline or 0.15 mg kg(-1) ketamine before surgery, followed by a continuous infusion of 1.4 microg kg(-1) min(-1) over 24 h. After sevoflurane induction and tracheal intubation, a caudal anaesthesia was performed in all children (1 ml kg(-1) of bupivacaine 0.25% with epinephrine). The postoperative analgesic technique was standardized with intravenous paracetamol 15 mg kg(-1) 6 h(-1), rectal morniflumate (20 mg kg(-1) 12 h(-1)) and intravenous nalbuphine infusion 1.2 mg kg(-1) 24 h(-1) for 24 h. The Children's Hospital of Eastern Ontario Pain Scale (CHEOPS) scores, additional bolus of nalbuphine (if CHEOPS >7) and side effects were recorded from eye opening every 2 h over 24 h. The primary endpoint was the CHEOPS area under the curve. There was no difference in terms of additional bolus of nalbuphine as well as CHEOPS score area under the curve between groups, that is, 76 +/- 10 in the ketamine group versus 74 +/- 7 in the control group. No psychomimetic side effects were noted. The study failed to show any evidence of benefit of ketamine to improve analgesia in children when given in addition to a multimodal analgesic therapy with paracetamol, a NSAID and an opiate.