ANESTHESIA WITH INCREASING DOSES OF SUFENTANIL AND MIDLATENCY AUDITORY-EVOKED POTENTIALS IN HUMANS

Our interest focused on the question whether sufentanil differs from a lfentanil fentanyl, and morphine with regard on its effects on midlate ncy auditory evoked potentials (MLAEP). Therefore, we studied MLAEP du ring general anesthesia with increasing doses of sufentanil in 16 pati ents scheduled for elective major urologic surgery. Anesthesia was ind uced with sufentanil (1 mu g/kg every 7 min to a total dose of 3 mu g/ kg). In 8 of 16 patients, further incremental doses of sufentanil were given to a total dose of 5 mu g/kg. Auditory evoked potentials were r ecorded before and 5 min after every sufentanil dose on vertex (positi ve) and mastoids on both sides (negative). Latencies of the peaks V, N a, 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 amplitu des and a periodic waveform. During general anesthesia the brainstem r esponse V was stable to increasing doses of sufentanil. There was a ma rked statistically significant increase in latency and decrease in amp litude of Nb and P1 after 1-2 mu g/kg sufentanil, which remained stabl e under further sufentanil application. In contrast, the early cortica l potentials Na and Pa increased only slightly in latencies. This incr ease was statistically significant at 4 mu g/kg for Na and at 3 and 4 mu g/kg for Pa. For the amplitudes Na/Pa and Pa/Nb there was only a sl ight and statistically insignificant reduction. After the largest dose of sufentanil (3-5 mu g/kg) Na and Pa showed a similar pattern as in awake patients. We conclude that sufentanil does not differ essentiall y from alfentanil, fentanyl, and morphine with regard on its effects o n MLAEP.