Electroencephalographic features of elderly patients during anesthesia induction with remimazolam: a sub-study of a randomized controlled trial

Hyoungkyu Kim; Byoung-Kyong Min; Uncheol Lee; Ji-Hoon Sim; Gyu-Jeong Noh; Eun-Kyung Lee; Byung-Moon Choi

doi:10.1097/ALN.0000000000004904

Electroencephalographic features of elderly patients during anesthesia induction with remimazolam: a sub-study of a randomized controlled trial

Anesthesiology. 2024 Mar 18. doi: 10.1097/ALN.0000000000004904. Online ahead of print.

Authors

Hyoungkyu Kim¹, Byoung-Kyong Min², Uncheol Lee³, Ji-Hoon Sim⁴, Gyu-Jeong Noh⁵, Eun-Kyung Lee⁶, Byung-Moon Choi⁷

Affiliations

¹ Research professor, Ph.D., Center for Neuroscience Imaging Research, Institute for Basic Science (IBS), Sungkyunkwan University, Suwon 16419, Republic of Korea (kim.hyoungkyu@gmail.com).
² Professor, Ph.D., Department of Brain and Cognitive Engineering, Korea University, Seoul, Republic of Korea (min_bk@korea.ac.kr).
³ Associate professor, Ph.D., Department of Anesthesiology, Center for Consciousness Science, Center for the Study of Complex Systems, University of Michigan Medical School, Ann Arbor, MI, United States (uclee@med.umich.edu).
⁴ Assistant professor, M.D., Ph.D., Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea (jihoon_sim@amc.seoul.kr).
⁵ Professor, M.D., Ph.D., Department of Anesthesiology and Pain Medicine and Department of Clinical Pharmacology and Therapeutics, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea (nohgj@amc.seoul.kr).
⁶ Professor, Ph.D., Department of Statistics, Ewha Womans University, Seoul, Korea (lee.eunk@ewha.ac.kr).
⁷ Professor, M.D., Ph.D., Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea (byungmoonchoi7@gmail.com).

PMID: 38207285
DOI: 10.1097/ALN.0000000000004904

Abstract

Background: Although remimazolam is used as a general anesthetic in elderly patients due to its hemodynamic stability, the electroencephalogram (EEG) characteristics of remimazolam are not well-known. The purpose of this study was to identify the EEG features of remimazolam-induced unconsciousness in elderly patients and compare them with propofol.

Methods: Remimazolam (n=26) or propofol (n=26) were randomly administered for anesthesia induction in surgical patients. The hypnotic agent was blinded only to the patients. During the induction of anesthesia, remimazolam was administered at a rate of 6 mg/kg/h, and propofol was administered at a target effect-site concentration of 3.5 μg/ml. The EEG signals from 8 channels (Fp1,Fp2,Fz,F3,F4,Pz,P3,P4, referenced to A2, using the 10-20 system) were acquired during the induction of anesthesia and in the postoperative care unit. Power spectrum analysis was performed, and directed functional connectivity between frontal and parietal regions was evaluated using normalized symbolic transfer entropy. Functional connectivity in unconscious processes induced by remimazolam or propofol was compared with baseline. To compare each power of frequency over time of the two hypnotic agents, a permutation test with t statistic was conducted.

Results: Compared to the baseline in the alpha band, the feedback connectivity decreased by an average of 46% and 43%, respectively, after the loss of consciousness induced by remimazolam and propofol (95% CI for the mean difference:-0.073 to -0.044 for remimazolam, P<0.001,-0.068 to -0.042 for propofol,P<0.001). Asymmetry in the feedback and feedforward connectivity in the alpha band was suppressed after the loss of consciousness induced by remimazolam and propofol. There were no significant differences in the power of each frequency over time between the two hypnotic agents (minimum q-value=0.4235).

Conclusions: Both regimens showed a greater decrease in feedback connectivity compared to a decrease in feedforward connectivity after loss of consciousness, leading to a disruption of asymmetry between the frontoparietal connectivity.