{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T02:23:55Z","timestamp":1760235835978,"version":"build-2065373602"},"reference-count":30,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2021,9,28]],"date-time":"2021-09-28T00:00:00Z","timestamp":1632787200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Medicina"],"abstract":"<jats:p>Background and Objectives: Phase lag entropy, an electroencephalographic monitor, evaluates the variety in temporal patterns of phase relationship between frontal and prefrontal brain region. Phase lag entropy can reflect the depth of anesthesia induced by propofol, but the association between sevoflurane and phase lag entropy has not been elucidated. This study examined the effect of sevoflurane on phase lag entropy during induction of general anesthesia. We also explored the pharmacodynamic model between end-tidal anesthetic concentration and electroencephalographic monitor. Materials and Methods: A total of 20 patients were enrolled. General anesthesia was produced by escalating the sevoflurane (1 vol% up to 8 vol%). The relationship between phase lag entropy and end-tidal anesthetic concentration was analyzed. A non-linear mixed-effects model was used to get the relationship of pharmacodynamics between the end-tidal sevoflurane concentration and phase lag entropy. Mean blood pressure, heart rate, and the modified observer\u2019s assessment of alertness\/sedation scale were also recorded during sevoflurane anesthesia. Results: As level of sedation increased, phase lag entropy decreased. A significant correlation was showed between phase lag entropy and end-tidal sevoflurane concentration (r = \u22120.759, p &lt; 0.001). The correlation coefficient between the modified observer\u2019s assessment of alertness\/sedation scale and phase lag entropy was 0.731 (p &lt; 0.001). The pharmacodynamic factors assessed by the sigmoid Emax model were E0 = 84.9, Emax = 42, Ce50 = 1.81, \u03b3 = 4.78, and ke0 = 0.692. The prediction probability of phase-lag entropy for measuring the modified observer\u2019s assessment of alertness\/sedation scale and end-tidal sevoflurane concentration were 0.764 and 0.789, respectively. With the increasing concentration of sevoflurane, mean blood pressure decreased, but heart rate did not change. Conclusions: The continuing escalation in end-tidal sevoflurane concentration caused a decline in phase lag entropy. Phase lag entropy can serve as an indicator of hypnotic depth in patients receiving sevoflurane anesthesia.<\/jats:p>","DOI":"10.3390\/medicina57101034","type":"journal-article","created":{"date-parts":[[2021,9,28]],"date-time":"2021-09-28T21:38:09Z","timestamp":1632865089000},"page":"1034","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Phase Lag Entropy as a Surrogate Measurement of Hypnotic Depth during Sevoflurane Anesthesia"],"prefix":"10.3390","volume":"57","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-6893-1539","authenticated-orcid":false,"given":"Kyung-Mi","family":"Kim","sequence":"first","affiliation":[{"name":"Department of Anesthesiology and Pain Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul 05505, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Ki-Hwa","family":"Lee","sequence":"additional","affiliation":[{"name":"Department of Anesthesiology and Pain Medicine, Haeundae Paik Hospital, Inje University School of Medicine, Busan 47392, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jae-Hong","family":"Park","sequence":"additional","affiliation":[{"name":"Department of Anesthesiology and Pain Medicine, Haeundae Paik Hospital, Inje University School of Medicine, Busan 47392, Korea"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2021,9,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1264","DOI":"10.1097\/ALN.0b013e31829103f5","article-title":"Disruption of frontal-parietal communication by ketamine, propofol, and sevoflurane","volume":"118","author":"Lee","year":"2013","journal-title":"Anesthesiology"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"876","DOI":"10.1126\/science.1149213","article-title":"Consciousness and Anesthesia","volume":"322","author":"Alkire","year":"2008","journal-title":"Science"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"200","DOI":"10.1016\/j.neuron.2011.03.018","article-title":"Experimental and Theoretical Approaches to Conscious Processing","volume":"70","author":"Dehaene","year":"2011","journal-title":"Neuron"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"990","DOI":"10.1097\/ALN.0000000000000436","article-title":"Effects of Sevoflurane and Propofol on Frontal Electroencephalogram Power and Coherence","volume":"121","author":"Akeju","year":"2014","journal-title":"Anesthesiology"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Oizumi, M., Albantakis, L., and Tononi, G. 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