[Balanced anesthesia with continuous ketamine reduces adverse effects of remifentanil]

We evaluated the use of continuous infusion of ketamine to reduce intraoperative remifentanil side effects, such as bradycardia and hypotension, and to improve postoperative analgesia from balanced anesthesia with remifentanil.

Forty patients undergoing spine surgery under remifentanil-based anesthesia were randomly assigned to intraoperative ketamine group and saline (control) group. Balanced anesthesia was maintained with infusion of propofol (2-4 mg x kg(-1) x hr(-1)), remifentanil (6-8 microg x kg(-1) hr(-1)) and vecuronium (60-80 microg x kg(-1) x hr(-1)) with nitrous oxide (60%) and with or without ketamine (300-400 microg x kg(-1) x hr(-)). All patients were given scheduled NSAIDs by their own doctor at the end of surgery. Intraoperative bradycardia (HR <50) and hypotension (SBP <80), and postoperative additional NSAIDs request were recorded.

Adverse events, such as bradycardia and hypotension, were less frequent in the ketamine group (P < 0.05). Less additional NSAIDs was required in the ketamine than in the control group (P < 0.05). Emergence time from anesthesia was within 5 min in both groups.

Remifentanil-based anesthesia with continuous ketamine decreases intraoperative side effects and postoperative NSAIDs request. Thus, intraoperative continuous ketamine may be a useful adjuvant to remifentanil.