Abstract
The auditory brainstem response (ABR) is a test widely used to assess the integrity of the brain stem. Although it is considered to be an auditory-evoked potential that is influenced by the physical characteristics of the stimulus, such as rate, polarity and type of stimulus, it may also be influenced by the change in several parameters. The use of anesthetics may adversely influence the value of the ABR wave latency. One of the anesthetics used for ABR assessment, especially in animal research, is the ketamine/xylazine combination. Our objective was to determine the influence of the ketamine/xylazine anesthetic on the ABR latency values in adult gerbils. The ABRs of 12 adult gerbils injected with the anesthetic were collected on three consecutive days, or a total of six collections, namely: pre-collection and A, B, C, D, and E collections. Before each collection the gerbil was injected with a dose of ketamine (100 mg/kg)/xylazine (4 mg/kg). For the capture of the ABR, 2000 click stimuli were used with rarefaction polarity and 13 stimuli per second, 80 dBnHL intensity and in-ear phones. A statistically significant difference was observed in the latency of the V wave in the ABR of gerbils in the C and D collections compared to the pre-, A and E collections, and no difference was observed between the pre-, A, B, and E collections. We conclude that the use of ketamine/xylazine increases the latency of the V wave of the ABR after several doses injected into adult gerbils; thus, clinicians should consider the use of this substance in the assessment of ABR.
Highlights
The brain stem auditory-evoked potential or auditory brainstem response (ABR) is a test used in clinical practice
Anesthetics are used for the ABR procedure at surgical centers and hospitals
This potential is used for surgical monitoring [13], when the patient is anesthetized and often presents hypothermia [14] and in situations in which the patient is evaluated after the surgical procedure, still under the effect of anesthesia
Summary
The brain stem auditory-evoked potential or auditory brainstem response (ABR) is a test used in clinical practice. Some patients are difficult to evaluate under these conditions and often need to be sedated [1] This potential is considered to be influenced by the physical characteristics of the stimulus, such as rate, polarity and type of stimulus, the use of anesthetics can alter the synaptic transmission, and this may be considered an adverse condition for testing the ABR [2]. Ketamine acts as a non-competitive antagonist of N-methyl-D-aspartate (NMDA), one of the glutamate receptors. It interferes with the action of NMDA, blocking the open channel and/or binding to the closed channel, reducing the opening frequency of the channel. These receptors reduce noradrenaline release by inhibiting the influx of calcium in the neuron, with a consequent hypotensive and tranquilizing effect [4]
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