P38-T Relevance of SSEP amplitude after cardiac arrest

Abstract

Background Absent N20 SSEP responses at 48–72 h and unfavorable EEG patterns at 24 h (suppressed, low voltage, or synchronous patterns with suppressed background) are reliable predictors of poor outcome of comatose patients after cardiac arrest. Here we present the additional predictive value of SSEP amplitude. Materials and methods This is a retrospective analysis of a prospective cohort study of 129 comatose patients who underwent SSEP and EEG recordings after cardiac arrest in two hospitals. EEG was recorded up to 5 days after cardiac arrest. SSEPs were generally recorded between 48 and 72 h. Absent SSEP responses, unfavorable EEG at 24 h, and SSEP amplitude were related to poor outcome (Cerebral Performance Category (CPC) of 3–5 at six month after cardiac arrest). Results Ninety-eight patients had a poor outcome (CPC 3–5). Bilaterally absent N20 responses were present in forty-one patients (42%) and invariably associated with a poor outcome. Unfavorable EEG at 24 h was present in thirty-five patients (36%), of which nine had preserved SSEP responses (9%), and also invariably associated with poor outcome. N20 amplitude 0.4 μV was present in twelve patients (12%), of which eight (8%) did not have unfavorable EEG, and also invariably associated with a poor outcome. Combined, these measures predicted poor outcome with 100% specificity and 59% sensitivity. Conclusions SSEP amplitude analysis may contribute to reliable prediction of poor outcome after cardiac arrest. Results are currently validated in an independent dataset. Validations will also be presented.