Use of flumazenil for intraoperative arousal during spine fusion

The intraoperative arousal test is used to detect potential damage to the spinal cord during spine fusion. We determined whether a continuous midazolam infusion, the effects of which are antagonized by flumazenil when the arousal test is needed, is associated with good control of the timing of arousal and with no adverse reactions. In a randomized study of 20 patients (10 in each group), we compared arousal with flumazenil during midazolam-narcotic anesthesia with an arousal test done during halothane-nitrous oxide anesthesia, both under conditions of controlled hypotension. Motor responses to verbal command were obtained 39.1 ± 36.0 s (mean ± SD) after the injection of flumazenil in eight patients. Two patients from this group awoke spontaneously 6 and 8 min after terminating the administration of nitrous oxide and midazolam but remained sedated up to the time of the test itself. In the halothane group, arousal occurred 26 ± 8.3 min after halothane administration was terminated and 10.1 ± 3.3 min after nitrous oxide was stopped. Two of the patients in this group moved,owing to early arousal 5 and 8 min before the scheduled time and needed reinstatement of anesthesia. In four patients in the halothane group, we had to wait 3-11 min after the scheduled time before satisfactory arousal was achieved. One of the patients in the halothane group showed a motor deficit of the lower limbs during the wake-up test that disappeared after decreasing the spine correction. There were no adverse reactions except for occasional shivering in the recovery period. No patient complained of any recall or unpleasant memories during the postoperative interview the following morning. We conclude that the midazolam-flumazenil technique for intraoperative arousal may be preferable to the discontinuation of halothane. The administration of flumazenil under these circumstances induces a rapid, easily controllable arousal, even under conditions of controlled hypotension.