Low dose ketamine prevents acute opioid tolerance induced by remifentanil infusion

Category Primary study
JournalEgyptian Journal Of Anaesthesia
Year 2005
BACKGROUND: Relative large-dose intraoperative remifentanil could lead to the need for more postoperative analgesics due to rapid development of acute opioid tolerance. Intraoperative n-methyl-d-aspartate receptor antagonists, such as ketamine, decrease postoperative opioid use. Therefore, we tested the hypothesis that intraoperative small-dose ketamine improves postoperative analgesia after major abdominal surgery with remifentanil-based anaesthesia. METHODS: sixty patients undergoing abdominal surgery under remifentanil-based anaesthesia were randomly assigned to intraoperative ketamine or saline (control) supplementation. The initial ketamine dose of 0.15 mg/kg was followed by 2 mug/kg/min. In both groups, sevoflurane was kept constant at 1.5 minimum alveolar anaesthetic concentration without n2o, and a remifentanil infusion was titrated to autonomic responses. All patients were given 0.15 mg/kg of morphine 30min before the end of surgery. Pain scores and morphine consumption were recorded for 24 postoperative hours. RESULTS: less of the remifentanil was required in the ketamine than in the control group (p<0.05). Pain scores were significantly higher in the control group during the first 15 postoperative min but were subsequently similar in the two groups. The ketamine patients required postoperative morphine later (p<0.05) and received less morphine during the first 24 postoperative hours: 37mg versus 59 mg (p<0.05). No psychotomimetic symptoms were noted in either group. CONCLUSION: supplementing remifentanil-based anaesthesia with small-dose ketamine prevents acute opioid tolerance induced by remifentanil infusion, so, it decreases intraoperative remifentanil use and postoperative morphine consumption without increasing the incidence of side effects. Thus, intraoperative small dose ketamine may be a useful adjuvant to intraoperative remifentanil.
Epistemonikos ID: 18e055d2ae01462515aebfa81e72a0ca112a05cc
First added on: Jul 19, 2016