Evidence

Summary of relevant research

Guidelines and Relevant Literature

European Society of Intensive Care Medicine, ESICM: Recommendations on the use of EEG monitoring in critically ill patients: consensus statement from the neurointensive care section of the ESICM.

Claassen et al.: Intensive Care Med . 2013 Aug;39(8):1337-51.

The panel recommends EEG

  • in generalized convulsive status epilepticus
  • to rule out nonconvulsive seizures in brain-injured patients
  • in comatose ICU patients without primary brain injury who have unexplained and persistent altered consciousness.

The panel suggests EEG

  • to detect ischemia in comatose patients with subarachnoid hemorrhage
  • to improve prognostication of coma after cardiac arrest.

We recommend continuous over intermittent EEG for refractory status epilepticus and suggest it for patients with status epilepticus and suspected ongoing seizures and for comatose patients with unexplained and persistent altered consciousness.

The American Clinical Neurophysiology Society, ACNS: “Consensus Statement on Continuous EEG in Critically Ill Adults and Children.

Herman, S.T., et al. (2015) J Clin Neurophysiol. 32(2): 87-95.

Continuous EEG recommended for:

  • diagnosis of nonconvulsive seizures, nonconvulsive status epilepticus, and other paroxysmal events, and for assessment of the efficacy of therapy for seizures and status epilepticus.

Continuous EEG suggested for:

  • identification of ischemia in patients at high risk for cerebral ischemia
  • assessment of level of consciousness in patients receiving intravenous sedation or pharmacologically induced coma, and
  • prognostication in patients after cardiac arrest

CCEEG has an important role in detection of secondary injuries such as seizures and ischemia in critically ill adults and children with altered mental status.

Neurocritical Care Society: Consensus Summary Statement of the International Multidisciplinary Consensus Conference on Multimodality Monitoring in Neurocritical Care

Le Roux, P. et al. (2014): Intensive Care Med. 40: 1189-1209.

This consensus summary statement from year 2014 recommends EEG monitoring:

  • urgently for status epilepticus patients,
  • for all patients with acute brain injury and unexplained and persistent altered consciousness and
  • for comatose cardiac arrest survivors during therapeutic hypothermia and within 24 hours of rewarming to exclude nonconvulsive epileptic seizures

Continuous EEG is also suggested for the following patient populations, whenever feasible:

  • Comatose ICU patient without an acute primary brain condition and with unexplained impairment of mental status or unexplained neurological deficits to exclude non-convulsive epileptic seizures, particularly in those with severe sepsis or renal/hepatic failure.
  • Detecting delayed cerebral ischemia (DCI) in comatose SAH patients, in whom neurological examination is unreliable

We recommend EEG in all patients with ABI [Acute Brain Injury] and unexplained and persistent altered consciousness […and] in patients with cSE that do not return to functional baseline within 60 minutes after seizure medication.

Neurocritical Care Society: Guidelines for Evaluation and Management of Status Epilepticus

Brophy, G. et al. (2012) Neurocrit Care 17(1):3-23.

Summary of cEEG Recommendations

  1. The use of continuous EEG monitoring (cEEG) is usually required for the treatment of SE.
  2. cEEG should be initiated within 1 h of SE onset if ongoing seizures are suspected
  3. The duration of cEEG monitoring should be at least 48 h in comatose patients to evaluate for non-convulsive seizures
  4. The person reading EEG in the ICU setting should have specialized training in cEEG interpretation, including the ability to analyze raw EEG as well as quantitative EEG tracing.

SE is often non-convulsive with the clinical findings of coma with or without subtle motor signs – In addition, non-convulsive seizures and NCSE exist in a high proportion of comatose patients with traumatic brain injury, intracranial hemorrhage, sepsis, cardiac arrest, or CNS infection. cEEG should be initiated within one hour of suspected SE in all patients. The duration of cEEG monitoring should be at least 48 h following acute brain insult in comatose patients and 24 h after cessation of electrographic seizures or during the AED weaning trials.

European Resuscitation Council and European Society of Intensive Care Medicine Guidelines 2021: post-resuscitation care

Nolan J.P. et al. Resuscitation. 2021; 161: 220-269.

Recommendation to always use a multi-modal approach for neuroprognosis, with EEG as one parameter that should be performed in patients who are unconscious after cardiac arrest.

Suggestion to use burst suppression on EEG at ≥ 24 h from ROSC in combination with other indices to predict poor outcome in comatose, unsedated, adult cardiac arrest patients.

Suggestion to measure seizure activity on EEG in combination with other indices to predict poor outcome in comatose adult cardiac arrest patients.

We recommend continuous over intermittent EEG for refractory status epilepticus and suggest it for patients with status epilepticus and suspected ongoing seizures and for comatose patients with unexplained and persistent altered consciousness.

2023 International Consensus on Cardiopulmonary Resuscitation and Emergency Cardiovascular Care Science With Treatment Recommendations: Summary From the Basic Life Support; Advanced Life Support; Pediatric Life Support; Neonatal Life Support; Education, Implementation, and Teams; and First Aid Task Forces

K.M. Berg et al. (2023) Circulation. 148(24):e187-e280.

Suggestion to use a continuous or nearly continuous normal-voltage EEG background without periodic discharges or seizures within 72 hours from ROSC in combination with other indices to predict good outcome in patients who are comatose after cardiac arrest.

2020 AHA CPR and ECC Guidelines

Panchal, A.R., et al. (2020) Circulation. 142 (suppl 2): S366-S468.

2023 AHA CPR and ECC Guidelines Update

Pernam S.M. et al., (2024) Circulation. 149(5):e254-273.

We recommend promptly performing and interpreting electroencephalopathy (EEG) for the diagnosis of seizures in patients who do not follow commands after ROSC.

PROPEA Stepcare

C-Trend® Index is included in PROPEA, a substudy of the STEPCARE trial.

The STEPCARE trial aims to study how to best prevent brain damage of resuscitated cardiac arrest survivors that receive critical care. It is an international, investigator-initiated, randomized trial on different aspects of standard care after out-of-hospital cardiac arrest. PROPEA Stepcare is one of STEPCARE’s substudies, concentrating on the restitution of electroencephalogram (EEG) slow wave activity (SWA) and its prognostic value in predicting favourable functional outcome after OHCA.

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2022 Guideline for the Management of Patients With Spontaneous Intracerebral Hemorrhage: A Guideline From the American Heart Association/American Stroke Association.

Greenberg, S.M., et al. (2022) Stroke. 53(7):e282-e361.

New-onset seizures in the context of spontaneous ICH are relatively common […] and most of these seizures occur within the first 24 hours of the hemorrhage.”--- “In patients with spontaneous ICH and unexplained abnormal or fluctuating mental status or suspicion of seizures, continuous electroencephalography (>24 hrs) is reasonable to diagnose electrographic seizures and epileptiform discharges.

2023 Guideline for the Management of Patients With Aneurysmal Subarachnoid Hemorrhage: A Guideline From the American Heart Association/American Stroke Association

Hoh, B.L., et al. (2023) Stroke. 54(7):e314-e370.

In patients with high-grade aneurysmal subarachnoid hemorrhage (aSAH), continuous EEG (cEEG) monitoring can be useful to predict delayed cerebral ischemia (DCI).

“Monitoring with continuous EEG can detect nonconvulsive seizures, especially in patients with depressed consciousness or fluctuating neurological examination.”

In patients with aSAH and either fluctuating neurological examination, depressed mental state, ruptured MCA aneurysm, high-grade SAH, ICH, hydrocephalus, or cortical infarction, cEEG monitoring is reasonable to detect seizures.

Forehead electrodes sufficiently detect propofol-induced slow waves for the assessment of brain function after cardiac arrest

Kortelainen J. et al. Journal of Clinical Monitoring and Computing 2020; Vol. 34, 105-110

Application of subhairline EEG montage in intensive care unit: comparison with full montage

Tanner A.E. et al. J Clin Neurophysiol. 2014; 31: 181-186

Predicting outcome in Postanoxic coma: are ten EEG electrodes enough?

Tjepkema-Cloostermans M.C. et al. J Clin Neurophysiol. 2017; 34: 207-212

Utility and rationale for continuous EEG monitoring: a primer for the general intensivist

Bitar et al., Critical Care (2024) 28:244.

In conclusion, cEEG monitoring is a cornerstone in critical care management, offering real-time insights into brain function and aiding clinical decision-making across neurological conditions. From guiding treatment strategies to enhancing prognostication accuracy, continuous EEG empowers healthcare providers to optimize patient care and outcomes in a complex and rapidly evolving landscape.

Evaluating the Impact of Point-of-Care Electroencephalography on Length of Stay in the Intensive Care Unit: Subanalysis of the SAFER-EEG Trial. Desai et al. Neurocrit Care

Desai et al. Neurocrit Care

In this study, we demonstrated shorter ICU LOS for patients in whom POC-EEG was chosen as an initial EEG modality compared to conv-EEG.

Utility of Quantitative EEG in Neurlogical Emergencies and ICU Clinical Practice

De Las Heras et al., Brain Sci. 2024, 14, 939.

The quantitative EEG (qEEG) added the possibility of long recordings being processed in a compressive manner, making EEG revision more efficient for experienced users, and more friendly for new ones. --- This article illustrates basic qEEG patterns encountered in critical care and adopts the new terminology proposed for spectrogram reporting.

Evaluating the Clinical Impact of Rapid Response Electroencephalography: The DECIDE Multicenter Prospective Observational Clinical Study

Vespa et al., Critical Care Medicine 48(9):p 1249-1257, September 2020.

Primary outcomes were changes in physicians’ diagnostic and therapeutic decision making and their confidence in these decisions based on the use of the rapid response electroencephalography system.

Pilot Study of Propofol-induced Slow Waves as a Pharmacologic Test for Brain Dysfunction after Brain Injury.

Kortelainen et al., Anesthesiology 2017; Vol. 126, 94-103.

In this experimental pilot study, the comatose postcardiac arrest patients with poor neurologic outcome were unable to generate normal propofol-induced electroencephalographic slow-wave activity 48 h after cardiac arrest.

Early recovery of frontal EEG slow wave activity during propofol sedation predicts outcome after cardiac arrest.

Kortelainen et al., Resuscitation 2021. Vol. 165, 170-176.

EEG SWA measured with C-Trend Index during propofol sedation offers a promising practical approach for early bedside evaluation of recovery of brain function and prediction of outcome after CA.

EDITORIAL: EEG registration after cardiac arrest: On the way to plug and play? Horn, J. et al.: Resuscitation 2021. Vol. 165, 182-183.

Horn, J. et al.: Resuscitation 2021. Vol. 165, 182-183.

---the general advice is shifting to a start of the EEG registration soon as possible after ICU admission, but this was not yet incorporated in the most recent official guidelines. --- This is easier said than done in most hospitals, especially as only 40% of all cardiac arrests occur during office hours. --- Even in centres where continuous EEG registration is well organised, it takes a mean of 11 h to start EEG recording.

More:

  • Early electroencephalography for outcome prediction of postanoxic coma: a prospective cohort study. Ruijter B.J. et al.: Ann Neurol. 2019; 86: 203-214
  • Standardized EEG interpretation accurately predicts prognosis after cardiac arrest. Westhall E. et al.: 2016; 86: 1482-1490
  • Value of EEG in outcome prediction of hypoxic-ischemic brain injury in the ICU: A narrative review. Hoedemaekers C, Hofmeijer J, Horn J. Resuscitation. 2023 Aug;189:109900. doi: 10.1016/j.resuscitation. 2023.109900. Epub 2023 Jul 5. PMID: 37419237.
  • Prediction of poor neurological outcome in comatose survivors of cardiac arrest: a systematic review. Sandroni et al. (2020) Intensive Care Med. 46(10):1803-1851.
  • Prediction of good neurological outcome in comatose survivors of cardiac arrest: a systematic review. Sandroni et al. (2022) Intensive Care Med. 48(4):389-413.

Continuous electroencephalography predicts delayed cerebral ischemia after subarachnoid hemorrhage: A prospective study of diagnostic accuracy

Rosenthal et al. (2018) Ann Neurol. 83(5):958-969.

cEEG accurately predicts DCI following SAH and may help target therapies to patients at highest risk of secondary brain injury.

Presence of electroencephalogram burst suppression in sedated, critically ill patients is associated with increased mortality

Watson et al., Critical Care Medicine 36(12):p 3171-3177, December 2008.

Burst-suppression with identical bursts: A distinct EEG pattern with poor outcome in postanoxic coma

Hofmeijer, J., Clinical Neurophysiology, Volume 125, Issue 5, May 2014, Pages 947-954.

Outcome prediction by amplitude-integrated EEG in adults with hypoxic ischemic encephalopathy

Tian, G. et al. Clin Neurol Neurosurg 2012 Jul;114(6):585-9.

Continuous Amplitude-Integrated Electroencephalographic Monitoring Is a Useful Prognostic Tool for Hypothermia-Treated Cardiac Arrest Patients

Oh, S.H., Circulation 2015. Volume 132, Number 12.

Quantitative EEG for the detection of brain ischemia

Foreman, B. et al., Crit Care. 2012; 16(2).

Defining abnormal slow EEG activity in acute ischaemic stroke: Delta/alpha ratio as an optimal QEEG index

Finnigan, S. et al., Clinical Neurophysiology Volume 127, Issue 2, Feb 2016, Pages 1452-145.

Continuous electroencephalography predicts delayed cerebral ischemia after subarachnoid hemorrhage: A prospective study of diagnostic accuracy

Rosenthal, E. et al., Ann Neurol. 2018 May;83(5):958-969. doi: 10.1002/ana.25232. Epub 2018 May 16