| Effect of low-dose volatile anesthetics on intraoperative neurophysiological monitoring during anesthesia with remimazolam |
Hee-Sun Park1, Wonho Choi1, Dong-Ho Lee2, Yong Seo Koo3, Se Keun Oh3, Won Uk Koh1 
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1Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
2Department of Orthopedic Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea
3Department of Neurology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea |
Corresponding author:
Won Uk Koh, Tel: +82-2-3010-5606, Fax: +82-2-3010-6790,
Email: koh9726@naver.com
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Received: 26 August 2024 • Revised: 27 March 2025 • Accepted: 27 March 2025 |
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| Abstract |
Background
Remimazolam is a novel short-acting benzodiazepine. We investigated the effects of low doses of volatile anesthetic agents on motor evoked potentials (MEPs) and somatosensory evoked potentials (SSEPs) during remimazolam-remifentanil anesthesia.
Methods
Thirty-nine patients undergoing cervical spine surgery were randomly assigned to either the sevoflurane (n = 20) or desflurane (n = 19) groups. Volatile anesthetic agents were administered at 0.3, 0.6, and 0.8 minimum alveolar concentration (MACs) during remimazolam-remifentanil anesthesia. Significant changes were considered as more than 50% amplitude suppression and more than 10% latency increase from baseline values. The primary outcome was MEP amplitude change. Secondary outcomes included MEP latency, SSEP amplitude and latency, and group comparisons.
Results
The MEP amplitudes were slightly reduced at 0.3 MAC; however, a suppression of more than 50% from baseline values at 0.3 MAC, particularly in the upper limbs, was observed in a notable proportion of participants; 30.0% and 47.4% in the sevoflurane and desflurane groups, respectively. The corresponding percentages for the lower limbs were 15.0% and 15.8%, respectively. MEP amplitude suppression was more than 50% in the majority of participants at 0.6 and 0.8 MAC. No significant difference was observed between the groups. SSEPs exhibited no significant amplitude suppression or latency prolongation across all MAC levels.
Conclusions
Notable MEP amplitude suppression was observed in many patients when 0.3 MAC volatile anesthetics were used as adjuncts. Therefore, even low doses of volatile anesthetics must be added cautiously to remimazolam-based anesthesia to prevent confounding. The SSEPs were relatively preserved, regardless of MAC. |
| Key Words:
Cervical vertebrae; Desflurane; Evoked potentials; Intraoperative neurophysiological monitoring; Remimazolam; Sevoflurane |
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