[Effects of high-dose fentanyl anesthesia on auditory brain stem responses].

It was previously reported that high-dose (50 micrograms.kg-1) fentanyl anesthesia had no effect on auditory brainstem response (ABR). However, the effect of the dose of 100 micrograms.kg-1 of fentanyl is unknown. We examined the effects of the dose of 50 micrograms.kg-1 and 100 micrograms.kg-1 of fentanyl on ABRs in 10 patients scheduled for cardiovascular surgery. No significant change was observed immediately after infusion of 50 micrograms.kg-1 of fentanyl, but peak latencies of waves I, III and V were significantly prolonged and the amplitude of wave V was significantly decreased immediately after infusion of 100 micrograms.kg-1 of fentanyl. The interpeak latencies of I-III and I-V were not affected. Therefore, prolongations of latencies of waves III and V were due to the change of latency of wave I. These results demonstrate that high-dose (100 micrograms.kg-1) fentanyl anesthesia depresses the peripheral auditory perception but dose not depress the central conduction.