Post resuscitation prognostication by EEG in 24 vs 48 h of targeted temperature management

Objective: To test if prognostic performance is affected by prolonged targeted temperature management (TTM) in comatose out-of-hospital cardiac arrest patients using two recently proposed EEG pattern classification models. Methods: In this sub-study of the Target Temperature Management for 48 vs. 24 hand Neurologic Outcome after Out-of-Hospital Cardiac Arrest: A Randomized Clinical Trial, EEGs of 20-30 min duration were collected 24 h and 48 h after reaching the target temperature of 33 +/- 1 degrees C. We classified EEGs according to two EEG classification models by Westhall et al. (highly malignant, malignant and benign) and Hofmeijer et al. (unfavorable, intermediate and favorable). We tested prognostic ability against 6 months functional outcome using the Cerebral Performance Category score. Results: We recorded EEGs in 120 patients at 24 h and in 44 patients at 48 h. We found no difference in specificities or sensitivities of the two models between the two TTM groups (all p-values >0.19) or in prognostication at 24 h compared to 48 h (all p-values >0.13), except for the presence of EEG reactivity favoring prognostication at 24 h (p < 0.001). Being classified in the benign or favorable category was strongly associated with good outcome with specificities of 100% (90-100) and 97% (85-100) for the Westhall and Hofmeijer models respectively. Conclusions: We found no difference in the prognostic performance of the two studied EEG classification models during prolonged TTM for 48 h compared to standard duration, nor between EEG classification performed at 24 h versus 48 h after reaching target temperature. The two models performed best in good outcome prediction.