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The purpose of this study was to simultaneously evaluate the effects of sevoflurane and propofol on an electroretinogram (ERG) and visual evoked potentials (VEPs). Twenty-four patients scheduled for elective surgery under general anesthesia were allocated randomly to receive either sevoflurane (group S) or propofol (group P). An ERG and VEPs were recorded in an awake state and during anesthesia with three different minimum alveolar concentrations (MAC; 0.5, 1.0, and 1.5) of sevoflurane in group S or with three different effect-site concentrations (Ce) of 2, 3, and 4 [mu]g/ml by using a target-controlled infusion technique in group P. Sevoflurane and propofol had little effect on amplitudes of the ERG b-wave. Sevoflurane significantly attenuated the amplitudes of VEP N75-P100 at 0.5, 1.0, and 1.5 MAC. Propofol did not significantly decrease the amplitude of VEPs at Ce of 2 or 3 [mu]g/ml but significantly decreased it at Ce of 4 [mu]g/ml. In summary, propofol and sevoflurane at clinical concentrations had little effect on the amplitude of an ERG. Sevoflurane attenuated the amplitudes of VEPs even at low concentrations. Propofol also attenuated the amplitudes of VEPs to a lesser extent compared to sevoflurane., Author(s): Ryusuke Tanaka [sup.1], Satoshi Tanaka [sup.1], Takashi Ichino [sup.1], Takashi Ishida [sup.1], Satoshi Fuseya [sup.1], Mikito Kawamata [sup.1] Author Affiliations: (1) grid.263518.b, 0000 0001 1507 4692, Department of Anesthesiology [...]

Purpose The aim of this study was to elucidate normative features of vagal motor-evoked potentials (MEPs) induced by transcranial electrical stimulation (TES) and to determine the influence of functional decline of the recurrent laryngeal nerve (RLN) on vagal MEPs during thyroid surgery. Methods A total of 54 patients undergoing elective thyroid surgery under general anesthesia were enrolled in this study. Vagal MEPs induced by TES were measured from the vocal cord using one of two types of electrodes (wire type or wide and flat type) mounted on an endotracheal tube. We investigated the effects of stimulation intensity and train pulse number on vagal MEP amplitude, the time course of vagal MEP amplitude during surgery, and the effects of functional decline of the RLN on vagal MEPs. Results The success rate of vagal MEP monitoring with wide- and flat-type electrodes was significantly higher than that with wire-type electrodes. Reliable vagal MEPs were obtained at a stimulation intensity of approximately 300 V with 3 or more pulses in 91% of the patients without preoperative RLN palsy (RLNP), and the amplitude was augmented with increasing stimulation intensity and train pulse number. Vagal MEP amplitude decreased during thyroid surgery and then partially recovered at the end of surgery. Vagal MEP amplitude recorded from the electrode ipsilateral to preoperative RLNP was significantly lower than that on the contralateral intact side. Conclusion Vagal MEPs induced by TES can be obtained with a high success rate during thyroid surgery and would reflect functional status of the RLN., Author(s): Takashi Ichino [sup.1], Satoshi Tanaka [sup.1], Ryusuke Tanaka [sup.1], Naruaki Tanaka [sup.1], Takashi Ishida [sup.1], Yuki Sugiyama [sup.1], Mikito Kawamata [sup.1] Author Affiliations: (1) 0000 0001 1507 4692, grid.263518.b, [...]