International consensus on EEG reactivity testing after cardiac arrest: Towards standardization

Area of Science:

• Neurology
• Critical Care Medicine
• Neurophysiology

Background:

• Electroencephalogram (EEG) reactivity is a proposed prognostic marker in patients after cardiac arrest (CA).
• Current guidelines for testing EEG reactivity and its interpretation are unspecific.
• Lack of standardized protocols hinders consistent clinical application.

Purpose of the Study:

• To establish international consensus on a standardized stimulus protocol for EEG reactivity testing.
• To define clear interpretation criteria for EEG reactivity in post-CA patients.
• To provide best-practice guidance for daily clinical care.

Main Methods:

• A two-round Delphi study involving 30 international experts in EEG for post-CA patients.
• Consensus defined as ≥75% agreement; 66-75% agreement resulted in recommendations.
• High response rates achieved: 80% in round one, 92% completion in round two.

Main Results:

• Consensus reached on stimulus protocol elements: clapping, calling patient's name, nail bed pressure, each repeated thrice for ≥5 seconds.
• Recommendations include pre-testing patient unstimulation and documenting sedation/analgesic use.
• Consensus definition of EEG reactivity: 'A reproducible change in the EEG in response to stimulation'.
• Exclusion criteria for reactivity: muscle/movement/eye blink artifacts, spinal movements, electrographic seizure induction.
• Agreement that the protocol is applicable to comatose patients from other etiologies.

Conclusions:

• This international consensus statement offers a starting point for EEG reactivity assessment in post-CA patients.
• The developed protocol provides best-practice guidance in the absence of extensive evidence.
• The consensus aims to improve prognostic accuracy and clinical decision-making for comatose patients.