What is the recommended stance on using EEG background reactivity to predict prognosis?

• A. It should be used alone.
• B. It should not be used to predict poor outcome.
• C. It guarantees outcome.
• D. It is irrelevant.

Answer: (B)

EEG background reactivity is a useful piece of information about cortical function after cardiac arrest, but it must be interpreted in the right context. Reactivity indicates the cortex can respond to stimuli, suggesting some preserved neural networks. However, many factors can suppress reactivity independent of eventual outcome—sedation and analgesia, neuromuscular blockade, therapeutic hypothermia, metabolic and electrolyte derangements, and timing after the event. Because these confounders can falsely dim or abolish reactivity early on, using EEG background reactivity by itself to predict a poor outcome can be misleading. The best approach is to view it as one part of a multimodal prognostic assessment, considering the clinical exam, imaging, biomarkers, and serial EEG data once confounders are minimized and a sufficient time has passed. It does not guarantee the final outcome, and it should not be treated as irrelevant, but not used in isolation to predict prognosis.