Marleen C Tjepkema-Cloostermans, Fokke B van Meulen, Gjerrit Meinsma, Michel JAM van Putten Critical Care 2013, 17:R252 (22 October 2013)
Introduction: Electroencephalogram (EEG) monitoring in patients treated with therapeutic hypothermia after cardiac arrest may assist in early outcome prediction. Quantitative EEG (qEEG) analysis can reduce the time needed to review long-term EEG, and makes the analysis more objective. In this study we evaluated the predictive value of qEEG analysis for neurological outcome in postanoxic patients.
Methods: In total, 109 patients admitted to the ICU for therapeutic hypothermia after cardiac arrest were included, divided over a training and a test set. Continuous EEG was recorded during the first 5 days or until ICU discharge. Neurological outcomes were based on the best achieved Cerebral Performance Category (CPC) score within six months. Of the training set 27 out of 56 patients (48%) and 26 out of 53 patients (49%) of the test set achieved good outcome (CPC 1–2). In all patients a five minute epoch was selected each hour, and five qEEG features were extracted. We introduced the Cerebral Recovery Index (CRI), which combines these features into a single number.
Results: At 24 hours after cardiac arrest, a CRI < 0.29 was always associated with poor neurological outcome, with a sensitivity of 0.55 (95% Confidence interval (CI): 0.32–0.76) at a specificity of 1.00 (CI: 0.86–1.00) in the test set. This results in a positive predictive value (PPV) of 1.00 (CI: 0.73–1.00) and a negative predictive value (NPV) of 0.71 (CI: 0.53–0.85). At the same time point a CRI >0.69 predicted good outcome, with a sensitivity of 0.25 (CI: 0.10–0.14) at a specificity of 1.00 (CI: 0.85–1.00) in the test set, and a corresponding NPV of 1.00 (CI: 0.54–1.00) and a PPV of 0.55 (CI: 0.38–0.70).
Conclusions: We introduced a combination of qEEG measures expressed in a single number, the CRI, which can assist in prediction of both poor and good outcome in postanoxic patients, within 24 hours after cardiac arrest.
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