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Aim: To assess if the amplitude of the N20 wave (N20Amp) of somatosensory evoked potentials (SSEPs) changes between 12–24 h and 72 h from the return of spontaneous circulation (ROSC) after cardiac arrest and if an N20Amp decrease predicts poor neurological outcome (CPC 3–5) at six months. Setting: Retrospective analysis of the ProNeCA multicentre prognostication study dataset. (NCT03849911). Methods: In adult comatose cardiac arrest survivors whose SSEPs were recorded at both 12–24 h and 72 h after ROSC, we measured the median N20Amp at each timepoint and the individual change in N20Amp across the two timepoints. We identified their cutoffs for predicting poor outcome with 0% false positive rate (FPR) and compared their sensitivities. Results: We included 236 patients. The median [IQR] N20Amp increased from 1.90 [0.78–4.22] µV to 2.86 [1.52–5.10] µV between 12–24 h and 72 h (p = 0.0019). The N20Amp cutoff for 0% FPR increased from 0.6 µV at 12–24 h to 1.23 µV at 72 h, and its sensitivity increased from 56[48–64]% to 71[63–77]%. Between 12–24 h and 72 h, an N20Amp decrease > 53% predicted poor outcome with 0[0–5]% FPR and 26[19–35]% sensitivity. Its combination with an N20Amp < 1.23 µV at 72 h increased sensitivity by 1% to 72[64–79]%. Conclusion: In comatose cardiac arrest survivors, the median N20Amp and its cutoff for predicting poor neurological outcome increase between 12–24 and 72 h after ROSC. An N20Amp decrease greater than 53% between these two timepoints predicts poor outcome with 0% FPR, confirming the unfavourable prognostic signal of a low N20Amp at 72 h.

Recent sttudies have shown that short-latency somatosensory (SSEP) amplitude as a predictor of outcome in post-anoxi coma is a continuous – rather than a dichotomous – variable. In addition, these studies showed that low-voltage SSEP is as reliable as a bilaterally absent SSEP for predicting severe hypoxic-ischaemic brain injury. Inevitably, when continuous variables are used to predict a dichotomous outcome (good vs. poor), there is a trade-off between sensitivity and specificity along the values of these variables, and we need to establish a threshold value to maximise the measure of accuracy that is more clinically relevant (in this case, specificity). The major problem with this approach is that these thresholds are often inconsistent across studies.

Background: Bilaterally absent pupillary light reflexes (PLR) or N20 waves of short-latency evoked potentials (SSEPs) are recommended by the 2015 ERC-ESICM guidelines as robust, first-line predictors of poor neurological outcome after cardiac arrest. However, recent evidence shows that the false positive rates (FPRs) of these tests may be higher than previously reported. We investigated if testing accuracy is improved when combining PLR/SSEPs with malignant electroencephalogram (EEG), oedema on brain computed tomography (CT), or early status myoclonus (SM). Methods: Post-hoc analysis of ProNeCA multicentre prognostication study. We compared the prognostic accuracy of the ERC-ESICM prognostication strategy vs. that of a new strategy combining ≥2 abnormal results from any of PLR, SSEPs, EEG, CT and SM. We also investigated if using alternative classifications for abnormal SSEPs (absent-pathological vs. bilaterally-absent N20) or malignant EEG (ACNS-defined suppression or burst-suppression vs. unreactive burst-suppression or status epilepticus) improved test sensitivity. Results: We assessed 210 adult comatose resuscitated patients of whom 164 (78%) had poor neurological outcome (CPC 3–5) at six months. FPRs and sensitivities of the ≥2 abnormal test strategy vs. the ERC-ESICM algorithm were 0[0−8]% vs. 7 [1–18]% and 49[41−57]% vs. 63[56−71]%, respectively (p < .0001). Using alternative SSEP/EEG definitions increased the number of patients with ≥2 concordant test results and the sensitivity of both strategies (67[59−74]% and 54[46−61]% respectively), with no loss of specificity. Conclusions: In comatose resuscitated patients, a prognostication strategy combining ≥2 among PLR, SSEPs, EEG, CT and SM was more specific than the 2015 ERC-ESICM prognostication algorithm for predicting 6-month poor neurological outcome.

Aims: To assess the accuracy of electroencephalogram (EEG) and somatosensory evoked potentials (SEPs) recorded at 12 and 72 h from resuscitation for predicting six-months neurological outcome in patients who are comatose after cardiac arrest. Methods: Prospective multicentre prognostication study. EEG was classified according to the American Clinical Neurophysiology Society terminology. SEPs were graded according to the presence and amplitude of their cortical responses. Neurological outcome was defined as good (cerebral performance categories [CPC] 1–3) vs. poor (CPC 4–5). None of the patients underwent withdrawal of life-sustaining treatment. Results: A total of 351 patients were included, of whom 134 (38%) had good neurological outcome. At 12 h, a continuous, nearly continuous and low-voltage EEG pattern predicted good neurological outcome with 71[61–80]% sensitivity, while an isoelectric EEG and a bilaterally absent/absent-pathological amplitude (AA/AP) cortical SEP pattern predicted poor neurological outcome with 14[8–21]% and 59[50–68]% sensitivity, respectively. Specificity was 100[97–100]% for all predictors. At 72 h, both an isoelectric, suppression or burst-suppression pattern on EEG and an AA/AP SEP pattern predicted poor outcome with 100[97–100]% specificity. Their sensitivities were 63[55–70]% and 66[58–74]%, respectively. When EEG and SEPs were combined, sensitivity for poor outcome prediction increased to 79%. Conclusions: In comatose resuscitated patients, EEG and SEPs predicted good and poor neurological outcome respectively, with 100% specificity as early as 12 h after cardiac arrest. At 72 h after arrest, unfavourable EEG and SEP patterns predicted poor neurological outcome with 100% specificity and high sensitivity, which further increased after their combination.

The data presented here are related to our research article entitled “Neurophysiology and neuroimaging accurately predict poor neurological outcome within 24 hours after cardiac arrest: a prospective multicentre prognostication study (ProNeCA)” [1]. We report a secondary analysis on the ability of somatosensory evoked potentials (SEPs), brain computed tomography (CT) and electroencephalography (EEG) to predict poor neurological outcome at 6 months in 346 patients who were comatose after cardiac arrest. Differently from the related research article, here we included cerebral performance category (CPC) 3 among poor outcomes, so that the outcomes are dichotomised as CPC 1–2 (absent to mild neurological disability: good outcome) vs. CPC 3–5 (severe neurological disability, persistent vegetative state, or death: poor outcome). The accuracy of the index tests was recalculated accordingly. A bilaterally absent/absent-pathological amplitude (AA/AP) N20 SEPs wave, a Grey Matter/White Matter (GM/WM) ratio <1.21 on brain CT and an isoelectric or burst suppression EEG predicted poor outcome with 49.6%, 42.2% and 29.8% sensitivity, respectively, and 100% specificity. The distribution of positive results of the three predictors did not overlap completely in the population of patients with poor outcome, so that when combining them the overall sensitivity raised to 61.2%.

Aims: To investigate the ability of 30-min electroencephalogram (EEG), short-latency somatosensory evoked potentials (SEPs) and brain computed tomography (CT) to predict poor neurological outcome (persistent vegetative state or death) at 6 months in comatose survivors of cardiac arrest within 24 h from the event. Methods: Prospective multicentre prognostication study in seven hospitals. SEPs were graded according to the presence and amplitude of their cortical responses, EEG patterns were classified according to the American Clinical Neurophysiology Society terminology and brain oedema on brain CT was measured as grey/white matter (GM/WM) density ratio. Sensitivity for poor outcome prediction at 100% specificity was calculated for the three tests individually and in combination. None of the patients underwent withdrawal of life-sustaining treatments before the index event occurred. Results: A total of 346/396 patients were included in the analysis. At 6 months, 223(64%) had poor neurological outcome; of these, 68 were alive in PVS. Bilaterally absent/absent-pathological amplitude cortical SEP patterns, a GM/WM ratio<1.21 on brain CT and isoelectric/burst-suppression EEG patterns predicted poor outcome with 100% specificity and sensitivities of 57.4%, 48.8% and 34.5%, respectively. At least one of these unfavourable patterns was present in 166/223 patients (74.4% sensitivity). Two unfavourable patterns were simultaneously present in 111/223 patients (49.7% sensitivity), and three patterns in 38/223 patients (17% sensitivity). Conclusions: In comatose resuscitated patients, a multimodal approach based on results of SEPs, EEG and brain CT accurately predicts poor neurological outcome at 6 months within the first 24 h after cardiac arrest.