The effect of ketamine/xylazine anesthesia on sensory and motor evoked potentials in the rat

Abstract

Study design: Experimental laboratory investigation of the eect of anesthesia on evoked potentials in rats. Objectives: To de®ne the optimal ketamine/xylazine anesthesia levels for the recording of dierent evoked potentials. Setting: BioSurgery Preclinical Department, Baxter BioScience, Vienna, Austria. Methods: Rats were implanted with cranial screws that allow stimulation and recording of evoked potentials. Somatosensory evoked potentials (SEPs), brainstem-derived motor evoked potentials (BMEPs) and corticomotor evoked potential (CMEPs) were recorded under dierent levels of anesthesia. The recorded signals were evaluated by measuring their latencies and amplitudes. The level of anesthesia was assessed by scoring the hind limb withdrawal re¯ex. Results: All three signals showed a strong dependency on the level of anesthesia. The observed eects, however, diered between the three signals. SEP amplitudes and latencies declined as animals slowly transgressed from deep to light anesthesia. In contrast, BMEP amplitudes were larger and latencies shorter in light anesthesia than in deep anesthesia. CMEPs ®nally were hard to record under deep anesthesia, but were easily recorded in light anesthesia. BMEPs that were recorded during light anesthesia also showed a signi®cant change in con®guration that was coupled with a notable increase in the variability of its amplitudes. Conclusions: The level of ketamine/xylazine anesthesia aects evoked potentials and thus should be controlled during electrophysiological recording. Our results suggest that SEPs should be best recorded during deep anesthesia, while BMEPs and CMEPs are best recorded during intermediate and light anesthesia.

Multi-limb acquisition of motor evoked potentials and its application in spinal cord injury

“…Further, we found that a combination Ketamine/Xylazine/Atropine cocktail allows for recording of high-amplitude MEPs during light anesthesia. This is consistent with other findings for a Ketamine/Xylazine cocktail (Green et al, 1981;Zandieh et al, 2003).…”

Thin-film epidural microelectrode arrays for somatosensory and motor cortex mapping in rat

“…Alternatively, variable depth of anaesthesia between sessions may explain SEP amplitude and latency fluctuations (the pharmacokinetics of anaesthetics can vary after intraperitoneal injection). The depth of ketamin/xylazine anaesthesia influences both, amplitude and latency of SEPs (Goss-Sampson and Kriss, 1991;Zandieh et al, 2003). Inhalation anaesthesia can improve the maintenance of a certain anaesthetic depth but will likely be accompanied by a depression of SEP amplitudes (Peterson et al, 1986).…”

Spectral Integration in Primary Auditory Cortex Attributable to Temporally Precise Convergence of Thalamocortical and Intracortical Input

“…Initial anesthesia was induced by inhalation of halothane (4%, 4 min) and was switched to a subcutaneous anesthesia with 45% ketamine (50 mg/ml; Ratiopharm), 5% xylazine (Rompun, 2%; BayerVital) and 50% isotonic sodium chloride solution (154 mmol/L; Braun). Status of anesthesia was maintained at surgical level by monitoring the hindlimb withdrawal reflex and respiratory rate (Zandieh et al, 2003). Body temperature was kept at 37°C by a controlled heating blanket.…”