Continuous EEG in therapeutic hypothermia after cardiac arrest: Prognostic and clinical value

Objectives: To determine the prognostic value of an EEG grading scale and clinical outcome of treated seizures detected with continuous EEG (cEEG) during therapeutic hypothermia (TH) and rewarming post cardiac arrest (CA). Methods: Our cohort study retrospectively reviewed the electronic medical records and cEEGs of all patients undergoing TH after CA under protocol over 2 years. cEEG was initiated during TH and continued until restoration of normothermia (NT). EEGs were graded 1-3 (3 = most severe) using a departmentally developed EEG severity grading scale by 2 authors blinded to clinical outcome. Outcome was measured using the Cerebral Performance Category scale; grades 1-2 were considered a "good" outcome, 3-5 "poor." Results: Fifty-four patients were included; 51 remained on cEEG through NT. Nineteen died. EEG severity grading during both TH and NT statistically correlated with outcome (grade 1 = good, grade 3 = poor). Other EEG features correlating with poor outcome included seizures, nonreactive background, and epileptiform discharges. Changes in EEG grade during monitoring did not statistically correlate with outcome. Five patients had seizures; all occurred in patients with grade 3 EEG backgrounds and all had a poor outcome. Conclusion: Grades 1 and 3 on our EEG severity grading scale during TH and NT correlated with outcome. Treating seizures did not improve outcome in our cohort.