Clinical paperNeurological pupil index and its association with other prognostic tools after cardiac arrest: A post hoc analysis
Introduction
Prognostication of neurological outcomes in comatose cardiac arrest (CA) patients plays a pivotal role, to minimize improper therapies in patients with irreversible brain injury, improving the quality of care in patients with a good chance of survival and the communication with the relatives to avoid false expectations.1 The 2021 European Resuscitation Council (ERC)/ European Society of Intensive Care Medicine (ESICM) guidelines for post-resuscitation care2 suggested a multimodal prognostic algorithm in this setting. According to this algorithm, an unfavorable neurological outcome is likely in the presence of two or more of the following: a) highly malignant patterns at electroencephalography (EEG); b) neuron-specific enolase (NSE) > 60 mcg/L at 48–72 hours from the return of spontaneous circulation (ROSC); c) bilateral absence of cortical response of short-latency somatosensory evoked potentials (SSEPs) at more than 24 hours from ROSC; d) presence of status myoclonus ≤ 72 hours from ROSC; e) extensive hypoxic-ischemic brain injury on brain imaging; f) bilateral absence of pupillary and corneal reflex at ≥ 72 hours from ROSC. The assessment of pupillary reactivity with automated pupillometry (AP) may improve outcome prediction and reduce the bias of standard manual evaluation.3 In a multicenter study,3 which aimed to compare prognostic performance of standard vs quantitative assessment of PLR, a neurological pupil index (NPi) ≤ 2 at 24–72 h from ROSC had 100 % specificity and 32 % sensitivity for unfavorable outcome in this setting.
Compared to the 2015 guidelines, the updated 2021 guidelines introduced the principle of concordance among test results. In case of discordance between those tests, a prognostic reassessment is recommended to avoid misclassification and false-positive predictions. As available tools evaluate different cerebral areas and pathways with variable sensitivity to the anoxic injury, more analyses on concordance among different predictors are necessary. In this setting, no data evaluating NPi with other recommended prognostic factors are available.
The aim of this study was therefore to assess the concordance of NPi with other prognostication tools in unconscious patients suffering from post-anoxic brain injury.
Section snippets
Study design
This is a post hoc analysis of a prospective, multicentric international prognostic study involving 10 European intensive care units and enrolling 456 comatose patients following CA.3 The different centers were selected, through the ESICM Neuro-Intensive Care Section, based on their experience with neuro-prognostication of CA patients. The study protocol was approved by the Ethics Committee of each institution, and informed consent to participate in the study was obtained from the patients'
Patients’ characteristics
A total of 456 patients were enrolled in the study; of those, 186 (41 %) were included in the MMM group for concordance analysis. The characteristics of the study population are presented in Table 1. A total of 269 patients (59 %) had UO. Patients in the MMM group were less frequently of male gender and had higher temperature during TTM compared to patients without MMM; patients in the MMM group also presented more frequently with N20ABS, discontinuous EEG and myoclonus than others, and had a
Discussion
In this study, we observed that in unconscious adult patients after resuscitation from cardiac arrest: a) NPi values were significantly lower among patients with myoclonus, abnormal EEG or SSEPs findings and high NSE levels; b) NPi values ≤ 2 had a good concordance with other predictors of UO, such as high NSE levels, discontinuous EEG or N20ABS; c) the higher the number of concordant predictors of UO in the same patient the higher was the rate of UO.
Our multicenter study showed a good
Conclusions
In our study, an abnormal NPi was associated with other important signs of hypoxic-ischemic brain injury, supporting its value as a predictor of UO after cardiac arrest.
Ethics approval and consent to participate
The original study protocol was approved by the ethics committees and the informed written consent was waived for the post-hoc design of the study.
Availability of data and materials
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
Funding
No funding was obtained to this study.
Authors' contributions
LP, CS and FST conceived the study; LP, AM and FST selected the population; LP, AM and FST conducted the statistical analysis and wrote the first draft of the paper; all the other authors revised the text for intellectual content.
Conflict of interest
We declare FST, GC and MO as scientific advisors for NeurOptics Inc. The other authors have no conflict of interest to declare.
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