Depth of anaesthesia monitoring: updated evidence. Comment on Br J Anaesth 2023; 131: 196–9

Editor—I was interested to read the editorial by McCulloch and Sanders 1 McCulloch T.J. Sanders R.D. Depth of anaesthesia monitoring: time to reject the index?. Br J Anaesth. 2023; 131: 196-199 Abstract Full Text Full Text PDF PubMed Scopus (4) Google Scholar addressing the value of depth of anaesthesia monitoring, in which they stated: 'Definitive evidence that these monitors reduce the risk of awareness under anaesthesia is lacking'. Furthermore, they stated: 'is it time to reject these indices?' I question this hesitancy. There is compelling evidence from large clinical trials, 2 Myles P. Leslie K. McNeil J. Forbes A. Chan M. Bispectral index monitoring to prevent awareness during anaesthesia: the B-Aware randomised controlled trial. Lancet. 2004; 363: 1757-1763 Abstract Full Text Full Text PDF PubMed Scopus (960) Google Scholar , 3 Zhang C. Xu L. Ma Y.Q. et al. Bispectral index monitoring prevent awareness during total intravenous anesthesia: a prospective, randomized, double-blinded, multi-center controlled trial. Chin Med J. 2011; 124: 3664-3669 PubMed Google Scholar , 4 Lewis S.R. Pritchard M.W. Fawcett L.J. Punjasawadwong Y. Bispectral index for improving intraoperative awareness and early postoperative recovery in adults. Cochrane Database Syst Rev. 2019; 9: Cd003843 PubMed Google Scholar and also expert consensus statements and guidelines, 5 Nimmo A.F. Absalom A.R. Bagshaw O. et al. Guidelines for the safe practice of total intravenous anaesthesia (TIVA): joint guidelines from the Association of Anaesthetists and the Society for Intravenous Anaesthesia. Anaesthesia. 2019; 74: 211-224 Crossref PubMed Scopus (157) Google Scholar , 6 Checketts M.R. Alladi R. Ferguson K. et al. Recommendations for standards of monitoring during anaesthesia and recovery 2015: Association of Anaesthetists of Great Britain and Ireland. Anaesthesia. 2016; 71: 85-93 Crossref PubMed Scopus (365) Google Scholar , 7 APSF Committee on TechnologyAPSF-endorsed statement on revising recommendations for patient monitoring during anesthesia. 2022https://www.apsf.org/article/apsf-endorsed-statement-on-revising-recommendations-for-patient-monitoring-during-anesthesia/Date accessed: August 8, 2023 Google Scholar supporting the use of bispectral index (BIS) or similar depth of anaesthesia monitoring in at-risk patients. This is particularly strong for patients receiving total intravenous anaesthesia (TIVA). 4 Lewis S.R. Pritchard M.W. Fawcett L.J. Punjasawadwong Y. Bispectral index for improving intraoperative awareness and early postoperative recovery in adults. Cochrane Database Syst Rev. 2019; 9: Cd003843 PubMed Google Scholar , 5 Nimmo A.F. Absalom A.R. Bagshaw O. et al. Guidelines for the safe practice of total intravenous anaesthesia (TIVA): joint guidelines from the Association of Anaesthetists and the Society for Intravenous Anaesthesia. Anaesthesia. 2019; 74: 211-224 Crossref PubMed Scopus (157) Google Scholar , 6 Checketts M.R. Alladi R. Ferguson K. et al. Recommendations for standards of monitoring during anaesthesia and recovery 2015: Association of Anaesthetists of Great Britain and Ireland. Anaesthesia. 2016; 71: 85-93 Crossref PubMed Scopus (365) Google Scholar ,8 Pandit J.J. Andrade J. Bogod D.G. et al. The 5th National Audit Project (NAP5) on accidental awareness during general anaesthesia: summary of main findings and risk factors. Anaesthesia. 2014; 69: 1089-1101 Crossref PubMed Scopus (124) Google Scholar The most recent Cochrane review found that BIS-guided anaesthesia reduced the risk of intraoperative awareness in an unselected surgical population (odds ratio [OR]: 0.36, 95% confidence interval [CI]: 0.21–0.60; P<0.001). 4 Lewis S.R. Pritchard M.W. Fawcett L.J. Punjasawadwong Y. Bispectral index for improving intraoperative awareness and early postoperative recovery in adults. Cochrane Database Syst Rev. 2019; 9: Cd003843 PubMed Google Scholar Depth of anaesthesia monitoring: time to reject the index?British Journal of AnaesthesiaVol. 131Issue 2PreviewDepth of anaesthesia monitors can fail to detect consciousness under anaesthesia, primarily because they rely on the frontal EEG, which does not arise from a neural correlate of consciousness. A study published in a previous issue of the British Journal of Anaesthesia showed that indices produced by the different commercial monitors can give highly discordant results when analysing changes in the frontal EEG. Anaesthetists could benefit from routinely assessing the raw EEG and its spectrogram, rather than relying solely on an index produced by a depth of anaesthesia monitor. Full-Text PDF Depth of amnesia monitoring. Response to Br J Anaesth 2023; 131: e145–7British Journal of AnaesthesiaVol. 132Issue 2PreviewEditor—The recent correspondence by Myles1 seems to imply that we inadequately addressed the evidence for current 'depth of anaesthesia' monitors in our recent editorial2 on the study by Hight and colleagues3 that compared five depth of anaesthesia monitors. We are grateful to Myles1 for providing an updated meta-analysis of the evidence that processed electroencephalogram (EEG) monitoring reduces memory of intraoperative events. Full-Text PDF