This topic was selected because an evidence synthesis beats a textbook on it: the trials disagree, or the guidance has moved recently.
THE EVIDENCE
What each source contributes, and how strong it is
Study design first — a cohort and a randomised trial do not carry the same weight.
Design
Year
Journal
What it found
Guideline
2023
Neurocritical care
An international expert panel judged frontal processed EEG adequate for monitoring
Meta-analysis
2023
British journal of anaesthesia
Across nine trials and 4,648 patients, processed EEG guidance gave a pooled odds
Randomised trial
2004
England)
In adults at high risk of awareness having relaxant general anaesthesia, BIS-guided
Cohort
2022
Anesthesiology
Isoelectric EEG occurred in 32% of children aged three years or under during
Review
2026
Anesthesia and analgesia
Processed EEG indices may not reliably reflect hypnotic state in neonates and infants
Guideline
2020
Anesthesia and analgesia
The POQI consensus recommends EEG monitoring as part of the vital organ monitors
6 resolved citations behind this deck; every point above traces to one of them.
WHERE THE GUIDANCE SITS
What the guidelines and pooled evidence say
3 findings, each on the slide that follows.
Neurocritical care 2023
An international expert panel judged frontal processed EEG adequate for monitoring
An international expert panel judged frontal processed EEG adequate for monitoring sedation depth in ICU patients unfit for clinical evaluation
British journal of anaesthesia 2023
Across nine trials and 4,648 patients, processed EEG guidance gave a pooled odds
Across nine trials and 4,648 patients, processed EEG guidance gave a pooled odds ratio for delirium of 0.78 that did not reach significance, with…
Anesthesia and analgesia 2020
The POQI consensus recommends EEG monitoring as part of the vital organ monitors
The POQI consensus recommends EEG monitoring as part of the vital organ monitors
WHERE THE GUIDANCE SITS
An international expert panel judged frontal processed EEG adequate for monitoring
Guideline · Neurocritical care
An international expert panel judged frontal processed EEG adequate for monitoring sedation depth in ICU patients unfit for clinical evaluation, but only after staff complete specific training.
Processed Electroencephalogram-Based Monitoring to Guide Sedation in Critically Ill Adult Patients: Recommendations From an International Expert Panel-Based Consensus, Neurocritical care 2023 · PMID 35896766
WHERE THE GUIDANCE SITS
Across nine trials and 4,648 patients, processed EEG guidance gave a pooled odds
Meta-analysis · British journal of anaesthesia
Across nine trials and 4,648 patients, processed EEG guidance gave a pooled odds ratio for delirium of 0.78 that did not reach significance, with substantial heterogeneity.
Processed Electroencephalography-Guided General Anaesthesia to Reduce Postoperative Delirium: A Systematic Review and Meta-Analysis, British journal of anaesthesia 2023 · PMID 35183345
WHERE THE GUIDANCE SITS
The POQI consensus recommends EEG monitoring as part of the vital organ monitors
Guideline · Anesthesia and analgesia
The POQI consensus recommends EEG monitoring as part of the vital organ monitors, while finding insufficient evidence to recommend it for preventing delirium, neurocognitive disorder or postoperative mortality.
American Society for Enhanced Recovery and Perioperative Quality Initiative Joint Consensus Statement on the Role of Neuromonitoring in Perioperative Outcomes: Electroencephalography, Anesthesia and analgesia 2020 · PMID 31764163
WHAT THE TRIALS FOUND
In adults at high risk of awareness having relaxant general anaesthesia, BIS-guided
Randomised trial · England)
In adults at high risk of awareness having relaxant general anaesthesia, BIS-guided anaesthesia cut confirmed awareness from 11 cases to 2, a relative risk reduction of 82%.
Bispectral Index Monitoring to Prevent Awareness During Anaesthesia: The B-Aware Randomised Controlled Trial, Lancet (London, England) 2004 · PMID 15172773
THE NUMBERS
B-Aware: BIS cut confirmed awareness by 82%
2,463 adults at high risk, relaxant general anaesthesia.
The awareness benefit is the strongest thing processed EEG does, and it is separate from delirium.
Bispectral Index Monitoring to Prevent Awareness During Anaesthesia: The B-Aware Randomised Controlled Trial, Lancet (London, England) 2004 · PMID 15172773
IN PRACTICE
What the cohorts and reviews add
2 findings, each on the slide that follows.
Anesthesiology 2022
Isoelectric EEG occurred in 32% of children aged three years or under during
Isoelectric EEG occurred in 32% of children aged three years or under during anaesthesia, varied from 9% to 88% between hospitals
Anesthesia and analgesia 2026
Processed EEG indices may not reliably reflect hypnotic state in neonates and infants
Processed EEG indices may not reliably reflect hypnotic state in neonates and infants, so read the raw waveform, spectral edge frequency and density…
IN PRACTICE
Isoelectric EEG occurred in 32% of children aged three years or under during
Cohort · Anesthesiology
Isoelectric EEG occurred in 32% of children aged three years or under during anaesthesia, varied from 9% to 88% between hospitals, and was associated with moderate and severe hypotension.
Isoelectric Electroencephalography in Infants and Toddlers During Anesthesia for Surgery: An International Observational Study, Anesthesiology 2022 · PMID 35503999
IN PRACTICE
Processed EEG indices may not reliably reflect hypnotic state in neonates and infants
Review · Anesthesia and analgesia
Processed EEG indices may not reliably reflect hypnotic state in neonates and infants, so read the raw waveform, spectral edge frequency and density spectral array rather than trusting the index alone.
The Utility of Electroencephalography in Guiding General Anesthesia in Children, Anesthesia and analgesia 2026 · PMID 39475857
THE NUMBERS
Delirium and cognitive dysfunction, pooled
Cochrane review, six trials, 2,929 participants.
Moderate-quality evidence for delirium and 12-week cognition; the one-week effect is uncertain.
THE NUMBERS
Depth monitoring lowered delirium in older patients
1,155 patients over 60 analysed.
Time spent with BIS under 20 independently predicted delirium — the depth, not the monitor, is the exposure.
IN THE ROOM
What this changes about the next case
Colour is the strength of the evidence behind each step, not the urgency.
1
1
An international expert panel judged frontal processed EEG adequate for monitoring sedation depth in ICU patients unfit for clinical evaluation, but only after staff complete specific training.
2
2
The POQI consensus recommends EEG monitoring as part of the vital organ monitors, while finding insufficient evidence to recommend it for preventing delirium, neurocognitive disorder or postoperative mortality.
3
3
Across nine trials and 4,648 patients, processed EEG guidance gave a pooled odds ratio for delirium of 0.78 that did not reach significance, with substantial heterogeneity.
4
4
In adults at high risk of awareness having relaxant general anaesthesia, BIS-guided anaesthesia cut confirmed awareness from 11 cases to 2, a relative risk reduction of 82%.
5
5
Isoelectric EEG occurred in 32% of children aged three years or under during anaesthesia, varied from 9% to 88% between hospitals, and was associated with moderate and severe hypotension.
The oral-boards stem on the next slide puts these into one scenario.
KEY TAKEAWAYS
What to carry into the next case
An international expert panel judged frontal processed EEG adequate for monitoring
Neurocritical care 2023
Across nine trials and 4,648 patients, processed EEG guidance gave a pooled odds
British journal of anaesthesia 2023
In adults at high risk of awareness having relaxant general anaesthesia, BIS-guided
England) 2004
Isoelectric EEG occurred in 32% of children aged three years or under during
Anesthesiology 2022
An international expert panel judged frontal processed EEG adequate for monitoring
Questions I'll ask you in the room
How does your plan change if the patient is not optimised?
What is the physiology behind what we just did?
Talk me through the trade-off you made there.
What would make you abandon this plan and do something else?
Oral boards stem
A 74-year-old is having a long open aortic case under total intravenous anaesthesia. The processed EEG index sits at 32 for long stretches and the resident asks whether to titrate to it.
Board questions
1. You are anaesthetizing a neonate and the processed EEG index is displayed. According to a review of EEG use in children, why should the index alone not be trusted in neonates and infants, and which three elements of the EEG display should you read instead?
Show answer
Processed EEG indices may not reliably reflect hypnotic state in neonates and infants, so read the raw waveform, spectral edge frequency and density spectral array rather than trusting the index alone.
In the youngest patients the single index number may not reflect hypnotic state at all, so look at the raw waveform, the spectral edge frequency and the density spectral array.
The Utility of Electroencephalography in Guiding General Anesthesia in Children, Anesthesia and analgesia 2026 · PMID 39475857
2. The B-Aware randomised controlled trial studied adults at high risk of awareness having general anaesthesia with neuromuscular blockade. State what BIS-guided anaesthesia did to confirmed awareness in that trial, giving the number of cases in each group and the relative risk reduction.
Show answer
BIS-guided anaesthesia cut confirmed awareness from 11 cases to 2, a relative risk reduction of 82%.
B-Aware is the awareness trial, not a delirium or outcome trial: in high-risk adults receiving a relaxant, BIS guidance took confirmed awareness from 11 cases down to 2.
Bispectral Index Monitoring to Prevent Awareness During Anaesthesia: The B-Aware Randomised Controlled Trial, Lancet (London, England) 2004 · PMID 15172773
3. An international observational study recorded intraoperative EEG in children aged three years or under. State how often isoelectric EEG occurred overall, how much the rate varied between hospitals, and what clinical finding it was associated with.
Show answer
Isoelectric EEG occurred in 32% of children aged three years or under during anaesthesia, varied from 9% to 88% between hospitals, and was associated with moderate and severe hypotension.
Nearly a third of these young children went isoelectric at some point, and the nine-to-eighty-eight percent spread between hospitals tells you this is a practice variable, not an unavoidable one.
Isoelectric Electroencephalography in Infants and Toddlers During Anesthesia for Surgery: An International Observational Study, Anesthesiology 2022 · PMID 35503999
4. The ASER/POQI joint consensus statement on neuromonitoring addressed electroencephalography. State both halves of its position: what it recommends about EEG monitoring, and the specific outcomes for which it found the evidence insufficient to recommend EEG.
Show answer
The POQI consensus recommends EEG monitoring as part of the vital organ monitors, while finding insufficient evidence to recommend it for preventing delirium, neurocognitive disorder or postoperative mortality.
Use the EEG as a vital organ monitor, which is what POQI endorses, but do not claim it prevents delirium, neurocognitive disorder or death, because POQI found the evidence insufficient for that.
American Society for Enhanced Recovery and Perioperative Quality Initiative Joint Consensus Statement on the Role of Neuromonitoring in Perioperative Outcomes: Electroencephalography, Anesthesia and analgesia 2020 · PMID 31764163
The bottom lineAn international expert panel judged frontal processed EEG adequate for monitoring
Sources
[1] Processed Electroencephalogram-Based Monitoring to Guide Sedation in Critically Ill Adult Patients: Recommendations From an International Expert Panel-Based Consensus, Neurocritical care 2023 · PMID 35896766 open
[2] Processed Electroencephalography-Guided General Anaesthesia to Reduce Postoperative Delirium: A Systematic Review and Meta-Analysis, British journal of anaesthesia 2023 · PMID 35183345 open
[3] Bispectral Index Monitoring to Prevent Awareness During Anaesthesia: The B-Aware Randomised Controlled Trial, Lancet (London, England) 2004 · PMID 15172773 open
[4] Isoelectric Electroencephalography in Infants and Toddlers During Anesthesia for Surgery: An International Observational Study, Anesthesiology 2022 · PMID 35503999 open
[5] The Utility of Electroencephalography in Guiding General Anesthesia in Children, Anesthesia and analgesia 2026 · PMID 39475857 open
[6] American Society for Enhanced Recovery and Perioperative Quality Initiative Joint Consensus Statement on the Role of Neuromonitoring in Perioperative Outcomes: Electroencephalography, Anesthesia and analgesia 2020 · PMID 31764163 open