Neurological pupil index and its association with other prognostic tools after cardiac arrest: A post hoc analysis.

INTRODUCTION

We evaluated the concordance of the Neurological pupil Index (NPi) with other predictors of outcome after cardiac arrest (CA).

METHODS

Post hoc analysis of a prospective, international, multicenter study including adult CA patients. Predictors of unfavorable outcome (UO, Cerebral Performance Category of 3-5 at 3 months) included: a) worst NPi ≤ 2; b) presence of discontinuous encephalography (EEG) background; c) bilateral absence of N20 waves on somatosensory evoked potentials (N20); d) peak neuron-specific enolase (NSE) blood levels > 60 mcg/L; e) myoclonus, which were all tested in a subset of patients who underwent complete multimodal assessment (MMM).

RESULTS

A total of 269/456 (59 %) patients had UO and 186 (41 %) underwent MMM. The presence of myoclonus was assessed in all patients, EEG in 358 (78 %), N20 in 186 (41 %) and NSE measurement in 228 (50 %). Patients with discontinuous EEG, N20 or high NSE had a higher proportion of worst NPi ≤ 2. The accuracy for NPi to predict a discontinuous EEG, N20, high NSE and the presence of myoclonus was moderate. Concordance with NPi ≤ 2 was high for NSE, and moderate for discontinuous EEG and N20. Also, the higher the number of concordant predictors of poor outcome, the lower the observed NPi.

CONCLUSIONS

In this study, NPi ≤ 2 had moderate to high concordance with other unfavorable outcome prognosticators of hypoxic-ischemic brain injury. This indicates that NPi measurement could be considered as a valid tool for coma prognostication after cardiac arrest.