Outcome prediction in comatose patients following cardiac arrest remains challenging. Here, we assess the predictive performance of electroencephalography-based power spectra within 24?h from coma onset.

We acquired electroencephalography (EEG) from comatose patients (n?=?138) on the first day of coma in four hospital sites in Switzerland. Outcome was categorised as favourable or unfavourable based on the best state within three months. Data were split in training and test sets. We evaluated the predictive performance of EEG power spectra for long term outcome and its added value to standard clinical tests.

Out of 138 patients, 80 had a favourable outcome. Power spectra comparison between favourable and unfavourable outcome in the training set yielded significant differences at 5.2–13.2?Hz and above 21?Hz. Outcome prediction based on power at 5.2–13.2?Hz was accurate in training and test sets. Overall, power spectra predicted patients’ outcome with maximum specificity and positive predictive value: 1.00 (95% with CI: 0.94–1.00 and 0.89–1.00, respectively). The combination of power spectra and reactivity yielded better accuracy and sensitivity (0.81, 95% CI: 0.71–0.89) than prediction based on power spectra alone.

On the first day of coma following cardiac arrest, low power spectra values around 10?Hz, typically linked to impaired cortico-thalamic structural connections, are highly specific of unfavourable outcome. Peaks in this frequency range can predict long-term outcome.