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Anesthesia with Increasing Doses of Sufentanil and Midlatency Auditory Evoked Potentials in Humans

Our interest focused on the question whether sufentanil differs from alfentanil, fentanyl, and morphine with regard on its effects on midlatency auditory evoked potentials (MLAEP).Therefore, we studied MLAEP during general anesthesia with increasing doses of sufentanil in 16 patients scheduled for elective major urologic surgery. Anesthesia was induced with sufentanil (1 micro gram/kg every 7 min to a total dose of 3 micro gram/kg). In 8 of 16 patients, further incremental doses of sufentanil were given to a total dose of 5 micro gram/kg. Auditory evoked potentials were recorded before and 5 min after every sufentanil dose on vertex (positive) and mastoids on both sides (negative). Latencies of the peaks V, Na, Pa, Nb, and P1 (ms), and amplitudes Na/Pa, Pa/Nb, and Nb/P1 (mu V) were measured. In the awake state, MLAEP had high peak-to-peak amplitudes and a periodic waveform. During general anesthesia the brainstem response V was stable to increasing doses of sufentanil. There was a marked statistically significant increase in latency and decrease in amplitude of Nb and P1 after 1-2 micro gram/kg sufentanil, which remained stable under further sufentanil application. In contrast, the early cortical potentials Na and Pa increased only slightly in latencies. This increase was statistically significant at 4 micro gram/kg for Na and at 3 and 4 micro gram/kg for Pa. For the amplitudes Na/Pa and Pa/Nb there was only a slight and statistically insignificant reduction. After the largest dose of sufentanil (3-5 micro gram/kg) Na and Pa showed a similar pattern as in awake patients. We conclude that sufentanil does not differ essentially from alfentanil, fentanyl, and morphine with regard on its effects on MLAEP. (Anesth Analg 1995;80:499-505)