Effect of sevoflurane concentration on visual evoked potentials with pattern stimulation in dogs

Abstract

The purpose of this study was to investigate the effects of sevoflurane concentration on canine visual evoked potentials with pattern stimulation (P-VEPs). Six clinically normal laboratory-beagle dogs were used. The minimum alveolar concentration (MAC) of sevoflurane was detected from all subjects by tail clamp method. The refractive power of the right eyes of all subjects was corrected to −2 diopters after skiascopy. For P-VEP recording, the recording and reference electrode were positioned at inion and nasion, respectively, and the earth electrode was positioned on the inner surface. To grasp the state of CNS suppression objectively, the bispectral index (BIS) value was used. The stimulus pattern size and distance for VEP recording were constant, 50.3 arc-min and 50 cm, respectively. P-VEPs and BIS values were recorded under sevoflurane in oxygen inhalational anesthesia at 0.5, 1.0, 1.5, 2.0, 2.5 and 2.75 sevoflurane MAC. For analysis of P-VEP, the P100 implicit time and N75-P100 amplitude were estimated. P-VEPs were detected at 0.5 to 1.5 MAC in all dogs, and disappeared at 2.0 MAC in four dogs and at 2.5 and 2.75 MAC in one dog each. The BIS value decreased with increasing sevoflurane MAC, and burst suppression began to appear from 1.5 MAC. There was no significant change in P100 implicit time and N75-P100 amplitude with any concentration of sevoflurane. At concentrations around 1.5 MAC, which are used routinely to immobilize dogs, sevoflurane showed no effect on P-VEP.

Measurement of visual acuity in Beagle dog by visual evoked potential with pattern stimulation

“…The visual evoked potential (VEP) test is one of the examination that can evaluate visual acuity objectively. The VEP test is a method for detecting brain wave signals from the visual cortex induced by a light stimulus [ 2 , 4 ]. The VEP is classified into flash-stimulated VEP (F-VEP), which uses a flash stimulus and pattern-stimulated VEP (P-VEP), which uses a contrast-reversing checkerboard pattern stimulus.…”

Electrophysiologic evaluation of the visual pathway at different depths of sevoflurane anesthesia in diabetic rats

“…On the contrary, anesthetics like sevoflurane would potentiate the response to visual stimulation by counteracting the synaptic depression [ 10 ]. Older reports are not in agreement with these results, showing a decrease of VEP amplitude with an increase in sevoflurane anesthetic concentration [ 7 , 8 ].…”

Diagnosis of postretinal blindness caused by intracranial disease in three dogs

“…Visual evoked potentials (VEPs) are used to evaluate the visual pathway from the retina to the visual cortex (3) and can detect brain wave signals from the visual cortex induced by a light stimulus. VEPs are not painful (3); however, the waveform and timing of VEPs are variable, and dogs are often uncooperative, so sedation or general anesthesia is needed (4). Therefore, it is difficult to record VEPs in dogs for practical reasons (3).…”