Latency of auditory evoked potential monitoring the effects of general anesthetics on nerve fibers and synapses

AbstractAuditory evoked potential (AEP) is an effective index for the effects of general anesthetics. However, it’s unknown if AEP can differentiate the effects of general anesthetics on nerve fibers and synapses. Presently, we investigated AEP latency and amplitude changes to different acoustic intensities during pentobarbital anesthesia. Latency more regularly changed than amplitude during anesthesia. AEP Latency monotonically decreased with acoustic intensity increase (i.e., latency-intensity curve) and could be fitted to an exponential decay equation, which showed two components, the theoretical minimum latency and stimulus-dependent delay. From the latency-intensity curves, the changes of these two components (∆Land ∆I) were extracted during anesthesia. ∆Land ∆Imonitored the effect of pentobarbital on nerve fibers and synapses. Pentobarbital can induce anesthesia and two side effects, hypoxemia and hypothermia. The hypoxemia was not related with ∆Land ∆I. However, ∆Lwas changed by the hypothermia, whereas ∆Iwas changed by the hypothermia and anesthesia. Therefore, we conclude that, AEP latency is superior to amplitude for the effects of general anesthetics, ∆Lmonitors the effect of hypothermia on nerve fibers and ∆Imonitors a combined effect of anesthesia and hypothermia on synapses. When eliminating the temperature factor, ∆Imonitors the anesthesia effect on synapses.