Publication

Changes in Alpha Frequency and Power of the Electroencephalogram during Volatile-Based General Anesthesia.

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Last modified
  • 03/03/2025
Type of Material
Authors
    Paul Garcia, Emory UniversityDarren Hight, University of AucklandLogan J. Voss, Waikato District Health BoardJamie Sleigh, Waikato District Health Board
Language
  • English
Date
  • 2017
Publisher
  • Frontiers Media
Publication Version
Copyright Statement
  • Copyright © 2017 Hight, Voss, Garcia and Sleigh
License
Final Published Version (URL)
Title of Journal or Parent Work
ISSN
  • 1662-5137
Volume
  • 11
Start Page
  • 36
End Page
  • 36
Grant/Funding Information
  • Funding for this project was provided by the James S McDonald Foundation (Grant Award No. 220020346 to PSG).
  • PSG’s research efforts are supported in part by a Career Development Award #BX00167 (PI: PSG) from the United States Department of Veteran Affairs, Biomedical Laboratory Research and Development Service.
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Abstract
  • Oscillations in the electroencephalogram (EEG) at the alpha frequency (8-12 Hz) are thought to be ubiquitous during surgical anesthesia, but the details of how this oscillation responds to ongoing changes in volatile anesthetic concentration have not been well characterized. It is not known how often alpha oscillations are absent in the clinical context, how sensitively alpha frequency and power respond to changes in anesthetic concentration, and what effect increased age has on alpha frequency. Bipolar EEG was recorded frontally from 305 patients undergoing surgery with sevoflurane or desflurane providing general anesthesia. A new method of detecting the presence of alpha oscillations based on the stability of the rate of change of the peak frequency in the alpha range was developed. Linear concentration-response curves were fitted to assess the sensitivity of alpha power and frequency measures to changing levels of anesthesia. Alpha oscillations were seen to be inexplicably absent in around 4% of patients. Maximal alpha power increased with increasing volatile anesthetic concentrations in half of the patients, and decreased in the remaining patients. Alpha frequency decreased with increasing anesthetic concentrations in near to 90% of patients. Increasing age was associated with decreased sensitivity to volatile anesthesia concentrations, and with decreased alpha frequency, which sometimes transitioned into the theta range (5-7 Hz). While peak alpha frequency shows a consistent slowing to increasing volatile concentrations, the peak power of the oscillation does not, suggesting that frequency might be more informative of depth of anesthesia than traditional power based measures during volatile-based anesthesia. The alpha oscillation becomes slower with increasing age, even when the decreased anesthetic needs of older patients were taken into account.
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Research Categories
  • Engineering, Biomedical
  • Health Sciences, Medicine and Surgery

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