EEG monitoring in postanoxic coma

Objective: To evaluate the value of continuous electroencephalography (EEG) in early prognostication in patients treated with hypothermia after cardiac arrest. Design: Prospective cohort study. Setting: Medical Intensive Care Unit (ICU). Patients: Sixty patients admitted to the ICU for therapeutic hypothermia after cardiac arrest. Intervention: None. Measurements and Main Results: In all patients continuous EEG and daily somatosensory evoked potentials (SSEP) were recorded during the first 5 days of admission or until ICU discharge. Neurological outcomes were based on each patient’s best achieved Cerebral Performance Category (CPC) score within 6 months. Twenty-seven out of 56 patients (48%) achieved good neurological outcome (CPC 1–2). At 12 hrs after resuscitation, 43% of the patients with good neurological outcome showed continuous, diffuse slowed EEG rhythms, while this was never observed in patients with poor outcome. The sensitivity for predicting poor neurological outcome of low voltage and iso-electric EEG patterns 24 hrs after resuscitation was 40% (95% confidence interval (CI): 19%–64%) with a 100% specificity (CI: 86%–100%), while sensitivity and specificity of absent SSEP responses during the first 24 hrs were 24% (CI: 10%–44%), and 100% (CI: 87%–100%), respectively. The negative predictive value for poor outcome of low voltage and iso-electric EEG patterns was 68% (CI: 50%–81%), compared to 55% (CI: 40%–60%) for bilateral SSEP absence, both with a positive predictive value of 100% (CI 63%–100% and 59%–100% respectively). Burst suppression patterns after 24 hrs were also associated with poor neurological outcome, but not inevitably so. Conclusions: In patients treated with hypothermia, EEG monitoring during the first 24 hrs after resuscitation can contribute to the prediction of both good and poor neurological outcome. Continuous patterns within 12 hrs predicted good outcome. Iso-electric or low voltage EEGs after 24 hrs predicted poor outcome with a sensitivity almost two times larger than bilateral absent SSEP responses. 2 Continuous EEG for early prediction of outcome 13