A comparison of remifentanil and fentanyl in patients undergoing surgery for intracranial mass lesions

We compared the effects of remifentanil versus fentanyl during surgery for intracranial space-occupying lesions. Patients were randomly assigned to re ceive either remifentanil (0.5 mu g . kg(-1) . min(-1) IV during the induct ion of anesthesia reduced to 0.25 mu g . kg(-1) . min(-1) after endotrachea l intubation; n = 49) or fentanyl (dose per usual practice of the anesthesi ologist; n = 54). Anesthesia maintenance doses of isoflurane, nitrous oxide , and opioid were at the anesthesiologist's discretion for both groups. The re were no differences between opioid groups for the frequency of responses (hemodynamic, movement, and tearing) to intubation, pinhead holder placeme nt, skin incision, or closure of the surgical wound. Adverse event frequenc ies were similar between groups. Times to follow verbal commands (P < 0.001 ) and tracheal extubation (P = 0.04) were more rapid for remifentanil. The percentage of patients with a normal recovery score (were alert or arousabl e to quiet voice, were oriented, were able to follow commands, had motor fu nction unchanged from their preoperative evaluation, were not agitated, and had modified Aldrete Scores of 9-10) at 10 min after surgery was more for remifentanil (45% vs 18%; P = 0.005). By 20 min, no difference between grou ps existed (P = 0.27). Anesthesiologists used more isoflurane in the fentan yl group (4.22 vs 1.93 minimum alveolar anesthetic concentration hours). Ne urosurgeons, blinded to treatment group, favored the use of remifentanil. S imilar frequencies of light anesthesia responses and other adverse events s uggest that intraoperative depths of anesthesia were similar in the two gro ups. Under these conditions, emergence was more rapid with remifentanil. Th is is consistent with the necessity for less isoflurane use in the remifent anil group and the intrinsic rapid clearance of this opioid.