F108. The prognostic value of median nerve SSEP after cardiac arrest: Evaluation of severity of hypoxic-ischemic encephalopathy by brain autopsies

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Introduction The severity of hypoxic-ischemic encephalopathy (HIE) strongly determines outcome after cardiac arrest (CA). Bilaterally absent cortical median nerve somatosensory evoked potentials (SSEPs) have been shown to accurately predict poor prognosis. However, self-fulfilling prophecy due to withdrawal of life-sustaining therapy is an important bias in prognostication studies on CA patients. Brain autopsies in patients who died after CA provide a unique opportunity to verify prognostic parameters such as SSEPs. Methods We retrospectively identified CA patients from university hospitals in Berlin, Germany, Lund, Sweden and Arhus, Denmark, who died after initially successful resuscitation and for whom SSEPs for neuro-prognostication and brain autopsy were available. We blindly determined presence/absence and, if applicable, cortical peak-to-peak SSEP amplitudes from original recordings. Severity of HIE was quantified histopathologically according to the selective eosinophilic neuronal death (SEND) score. Results We identified 58 CA autopsy patients who had been investigated with SSEP. All 21 patients with bilaterally absent SSEP and all 5 with cortical SSEP amplitudes below 0.5 μV had severe HIE (SEND 2–4 in cortical regions). The highest cortical SSEP amplitude in a patient with severe HIE was 2.7 μV, all 11 patients with higher amplitudes had no/moderate HIE (SEND 0–1 in cortical regions). Conclusion We did not find evidence for a self-fulfilling prophecy in the prediction of poor neurological outcome by SSEP after cardiac arrest. Bilaterally absent cortical SSEP and very low SSEP amplitudes indicated histopathologically severe HIE whereas cortical SSEP amplitudes above 2.7 μV indicated absence of severe HIE.