[Changes in auditory evoked potentials during abdominal surgical interventions under anesthesia]

The changes in the parameters of average latent auditory potentials (ALAP) were studied in 23 adult patients under anesthesia (ASA II-III) during elective abdominal operations. General combined anesthesia (propofol, fentanyl, and N2O) were used in Group 1 (n = 12), it was combined with epidural anesthesia (lidocaine) in Group 2 (n = 11). General anesthesia was shown to cause a reduction in the amplitude of Pa and Nb peaks and an increase in their latency. Surgical nociceptive stimulation, on the contrary, increased the amplitude of these peaks and decreased their latency. When general anesthesia was applied alone, the magnitude of changes was ascertained to be significantly greater than when it was combined with epidural anesthesia. This suggests that the changes in ALAP reflect the full value and the degree of nociceptive current suppression.