Effect of ephedrine on auditory‐evoked potentials during light general anaesthesia

Abstract

SummaryEphedrine, a sympathomimetic drug, may stimulate the central nervous system via its amphetamine-like effect under light general anaesthesia. We compared the effect of ephedrine on auditory-evoked potentials with that of etilefrine, a sympathomimetic drug that lacks an amphetamine-like effect, in patients undergoing abdominal surgery under general anaesthesia with 67% nitrous oxide in oxygen and epidural blockade. Ephedrine (0.08 mg.kg À1 intravenously) signi®cantly decreased the latencies of Nb and P 1 from 49.5 (4.2) [mean (SD)] and 63.9 (9.1) ms to 45.9 (4.2) and 59.0 (9.9) ms, respectively; whereas etilefrine (0.02 mg.kg À1 intravenously) caused no signi®cant changes in these potentials. In addition, the latencies of Nb and P 1 before drug administration were positively correlated with patient age. These ®ndings suggest that ephedrine can cause excitation of the central nervous system during light general anaesthesia, and that auditory-evoked potentials may be a sensitive indicator of the depth of anaesthesia.

Combined use of Bispectral Index™ and A-Line™ Autoregressive Index™ to assess anti-nociceptive component of balanced anaesthesia during lumbar arthrodesis

“…Adrenergic medications are known to induce arousal, increase BIS and reduce latencies of MLAEPs in sedated patients. [22][23][24][25] This arousal effect is not observed when anaesthesia is deep enough to maintain BIS between 40 and 60, 22 as in our study. The number of patients receiving ephedrine during the study period was similar in both groups and no change in BIS or AAI was noted after administration of ephedrine.…”