Evoked potentials following diazepam or fentanyl.

The effects of fentanyl or diazepam on somatosensory, visual and brainstem auditory evoked potentials were studied in 13 healthy patients scheduled for elective surgery. Following control recordings of evoked potentials, either diazepam 20 mg or fentanyl 200 micrograms was administered intravenously. Evoked potentials were then recorded twice in the subsequent hour. No significant changes occurred in the latency or amplitude of somatosensory, visual or brainstem auditory evoked potentials. Although dose-related changes in evoked potential latencies and amplitudes have been demonstrated with both the inhalational and intravenous anaesthetics, these changes did not occur with diazepam or fentanyl used alone. An anaesthetic technique based on these two drugs would be suitable when intra-operative evoked potential monitoring is required to assess ischaemia and preservation of evoked responses.