The use of a remifentanil infusion for hemodynamic control during intracranial surgery

Remifentanil is an extremely rapid and short-acting opioid analgesic which is effective in controlling acute stress responses during surgery. During neurosurgical anesthesia, laryngoscopy and intubation, application of the head holder, scalp incision, and the craniectomy can produce significant increases in mean arterial pressure (MAP). In this dose-response study, we evaluated the efficacy of a remifentanil infusion in maintaining hemodynamic stability during intracranial surgery under desflurane anesthesia. Forty-five patients were assigned randomly to one of the three remifentanil infusion groups. All patients received a standardized anesthetic induction consisting of midazolam, 2 mg IV, Lidocaine 0.75 mg/kg IV, propofol 1.0 mg/kg IV, and remifentanil 0.5 mu g/kg IV. Immediately after induction of anesthesia, a remifentanil infusion was Started at 0.0625 mu g . kg(-1) . min(-1) (Group 1), 0.125 mu g . kg(-1) . min(-1) (Group 2), or 0.250 mu g . kg(-1) . min(-1) (Group 3) according to a double-blinded study protocol. Maintenance of anesthesia consisted of desflurane 3% (end-tidal) in air/oxygen. if the MAP exceeded 80 mm Hg, a supplemental bolus of remifentanil, 0.5 mu g/kg IV was administered, and when the MAP decreased below 65 mm Hg, the remifentanil infusion was discontinued temporarily. "Rescue" cardiovascular medications consisted of nitroprusside (100 mu g IV) or phenylephrine (100 mu g IV). Heart rate, systolic, diastolic, and MAP values, were recorded every minute for 20 min after each specific stimulus. The overall quality of the intraoperative hemodynamic control was evaluated by the attending anesthesiologist on a scale from 1 = poor to 5 = excellent. The overall quality of the hemodynamic control was superior in Group 2 compared with Group 1 (P < 0.05). Although the total dose of remifentanil administered during the study period did not differ among the three groups, Group 1 required significantly more supplemental boluses of remifentanil (66%-80%) than Groups 2 (13%-33%) and 3 (7%-13%), and the remifentanil infusion was discontinued more often in Group 3 (80%-93%) than in Groups 1 (0%- 13%) and 2 (21%-40%). In conclusion, the recommended remifentanil infusion rate for controlling acute autonomic responses during neurosurgical anesthesia is 0.125 mu g . kg(-1) . min(-1) when administered during a desflurane-based anesthetic. Implications: Compared with remifentanil 0.0625 mu g . kg(-1) . min(-1) and 0.250 mu g . kg(-1) . min(-1), a remifentanil infusion rate of 0.125 mu g . kg(-1) . min(-1) provided more stable hemodynamic conditions during intracranial surgery under desflurane anesthesia.