Auditory 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 (∆L and ∆I) were extracted during
anesthesia. ∆L and ∆I monitored 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 ∆L and ∆I. However, ∆L was changed by the
hypothermia, whereas ∆I was changed by the
hypothermia and
anesthesia. Therefore, we conclude that, AEP latency is superior to amplitude for the effects of
general anesthetics, ∆L monitors the effect of
hypothermia on nerve fibers, and ∆I monitors a combined effect of
anesthesia and
hypothermia on synapses. When eliminating the temperature factor, ∆I monitors the
anesthesia effect on synapses.