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Author Notes:

Correspondence: amy.gaskell@waikatodhb.health.nz

Initial concept and obtaining initial funding: JSW, DH, and PSG.

Study design and initial protocol: ALG and JSW.

Protocol development and refinement: all authors.

Local approvals and preliminary pilot work: ALG, RMP, JT, and GM.

Manuscript review and revisions and approval of manuscript: all authors.

We would like to thank Dr. John Barnard for his thoughtful protocol review and input.

The authors also gratefully acknowledge helpful discussions from ACCESS research conferences (anaesthesiologists focussed on cognition, emergence, sleep and sedation).

The authors declare that they have no competing interests.


Research Funding:

Dr. García’s research efforts are supported in part by a Career Q7 Development Award #BX00167 (PI: PS García, MD, PhD) from the United States Department of Veteran Affairs, Biomedical Laboratory Research and Development Service and the James S. McDonnell Foundation Grant #220023046 (PI: PS García, MD, PhD).

This study was also awarded a grant from the Shrimpton Fund (University of Auckland School of Medicine Foundation).

Amy Gaskell is supported by a PhD scholarship from the Australian and New Zealand College of Anaesthetists.

Support is also provided by local departments.


  • Science & Technology
  • Life Sciences & Biomedicine
  • Medicine, Research & Experimental
  • Research & Experimental Medicine
  • General anaesthesia
  • Anaesthesia emergence
  • Delirium
  • EEG monitoring
  • Elderly

Modulation of frontal EEG alpha oscillations during maintenance and emergence phases of general anaesthesia to improve early neurocognitive recovery in older patients: protocol for a randomised controlled trial

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Journal Title:



Volume 20, Number 1


, Pages 146-146

Type of Work:

Article | Final Publisher PDF


Background: Postoperative delirium may manifest in the immediate post-anaesthesia care period. Such episodes appear to be predictive of further episodes of inpatient delirium and associated adverse outcomes. Frontal electroencephalogram (EEG) findings of suppression patterns and low proprietary index values have been associated with postoperative delirium and poor outcomes. However, the efficacy of titrating anaesthesia to proprietary index targets for preventing delirium remains contentious. We aim to assess the efficacy of two strategies which we hypothesise could prevent post-anaesthesia care unit (PACU) delirium by maximising the alpha oscillation observed in frontal EEG channels during the maintenance and emergence phases of anaesthesia. Methods: This is a 2 × 2 factorial, double-blind, stratified, randomised control trial of 600 patients. Eligible patients are those aged 60 years or over who are undergoing non-cardiac, non-intracranial, volatile-based anaesthesia of expected duration of more than 2 h. Patients will be stratified by pre-operative cognitive status, surgery type and site. For the maintenance phase of anaesthesia, patients will be randomised (1:1) to an alpha power-maximisation anaesthesia titration strategy versus standard care avoiding suppression patterns in the EEG. For the emergence phase of anaesthesia, patients will be randomised (1:1) to early cessation of volatile anaesthesia and emergence from an intravenous infusion of propofol versus standard emergence from volatile anaesthesia only. The primary study outcomes are the power of the frontal alpha oscillation during the maintenance and emergence phases of anaesthesia. Our main clinical outcome of interest is PACU delirium. Discussion: This is a largely exploratory study; the extent to which EEG signatures can be modified by titration of pharmacological agents is not known. The underlying concept is maximisation of anaesthetic efficacy by individualised drug titration to a clearly defined EEG feature. The interventions are already clinically used strategies in anaesthetic practice, but have not been formally evaluated. The addition of propofol during the emergence phase of volatile-based general anaesthesia is known to reduce emergence delirium in children; however, the efficacy of this strategy in older patients is not known. Trial registration: Australian and New Zealand Clinical Trial Registry, ID: 12617001354370. Registered on 27/09/2017.

Copyright information:

© 2019 The Author(s).

This is an Open Access work distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creativecommons.org/licenses/by/4.0/).
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