Outcomes of Cardiac Arrest Predict By N20 & P25 Amplitudes


For a study, researchers sought to see if the amplitudes of 2 somatosensory evoked potentials (SSEP) responses, N20-baseline (N20-b) and N20–P25, were predictive of neurological prognosis in comatose individuals after cardiac arrest (CA). Between November 2019 and July 2021, a monocentric prospective study was conducted in a tertiary cardiac center. All unconscious patients 72 hours after CA and with at least 1 SSEP were included. The N20-b and N20–P25 amplitudes and other indicated prognostic indicators were automatically measured in microvolts (V) (status myoclonus, neuron-specific enolase levels at 2 and 3 days, and EEG pattern). At three months (primary endpoint) and six months (follow-up), investigators investigated the predictive efficacy of SSEP for neurologic outcomes using the best Cerebral Performance Categories (CPC1 or two as good outcome). The specificity and sensitivity of different SSEP amplitude thresholds were calculated alone or combined with additional prognostic markers. At three months, 78% of 82 patients had a poor outcome (CPC 3–5). The median duration from CA to SSEP recording was three days (2–4), with a pattern of “bilaterally absent” in 19 patients, “unilaterally present” in 4, and “bilaterally present” in 59. The median N20-b amplitudes were different between patients with poor and good outcomes, 0.93 [0–2.05]µV vs. 1.56 [1.24–2.75]µV, respectively (P<0.0001), as were the median N20–P25 amplitudes (0.57 [0–1.43]µV in bad result patients vs. 2.64 [1.39–3.80]µV in good outcome patients, P<0.0001). Although an N20–P25 greater than 3.2µV was 93% specific and only 30% sensitive, it indicated a positive outcome with a specificity of 73% and a moderate sensitivity of 39%. With a high specificity (sp=94% and 93%, respectively) and moderate sensitivity (se=50% and 66%), low voltage N20-bless than 0.88µV and N20–P25 less than 1µV indicated bad results. When “bilaterally absent or low voltage SSEP” patterns were combined, the sensitivity of “bilaterally absent” SSEP alone increased dramatically (se=58 vs. 30%, P=0.002) for predicting bad outcomes. Both N20-b and N20–P25 amplitudes might predict good and bad outcomes in comatose patients after CA, with high specificity but low to intermediate sensitivity. The outcomes implied that SSEP amplitudes should be utilized with caution in clinical practice and that these markers should be part of a multimodal approach to cardiac arrest prognosis.

Source:annalsofintensivecare.springeropen.com/articles/10.1186/s13613-022-00999-6



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