Utility of continuous EEG monitoring in postanoxic coma: a retrospective multicenter study

BACKGROUND: Following postanoxic coma, continuous electroencephalography (cEEG) monitoring is widely applied for prognostication, guided by national guidelines recommending multimodal assessment. While the diagnostic accuracy of cEEG is well-established, its actual outcomes and impact on intensive care unit (ICU) length of stay (LOS) have largely remained unreported since guideline implementation. This study evaluates outcomes and the unique prognostic value of cEEG monitoring in patients with postanoxic coma after guideline implementation.

METHODS: This retrospective multicenter study analyzed 699 patients with postanoxic coma who underwent cEEG monitoring between January 2021 and January 2024 across three Dutch academic centers. Prognostic outcomes (favorable, poor, or uncertain) were classified based on established EEG patterns at 12- and 24-hour timepoints. For patients with a poor cEEG prognosis, clinical indicators (neurological examination, hemodynamic stability, additional prognostic modalities) were assessed to determine cEEG's unique contribution.

RESULTS: Of 699 patients, 13.0% (n = 91) had a favorable, 16.2% (n = 113) a poor, and 70.8% (n = 495) an uncertain prognosis. Among those with a poor cEEG prognosis, 58% also had clinical indicators of a poor prognosis such as wide pupils with absent light reflexes or hemodynamic instability. Only 6.7% (n = 47) of all cEEGs provided unique additional prognostic value, with no other clinical indicators suggesting a poor prognosis.

CONCLUSIONS: cEEG monitoring provided unique prognostic information in a small percentage of cases, with most yielding uncertain prognoses. This suggests current universal cEEG monitoring may be suboptimal given resource constraints and limited additional diagnostic yield.