The best available pupil response predicts neurological outcome following cardiac arrest-a prospective cohort study

Abstract

Background:Early neuroprognostication after cardiac arrest (CA) remains challenging. Manual pupillary light reflex assessments can be inconsistent, leading to interest in automated, quantitative pupillometry. This study used the better Neurological Pupil Index (NPi) and pupillary percentage values from bilateral measurements for neuroprognostication following CA.

Methods:We evaluated 90 adult survivors of in- and out-of-hospital CA admitted to a medical ICU at a tertiary care university hospital in Berlin. Automated pupillometry was performed every 8 hours for 5 days post-admission using the NeurOptics NPi-100 pupillometer. The better measurement from either eye was selected for analysis. Outcomes at hospital discharge were classified as good (cerebral performance category scale [CPC] 1–2) or poor (CPC 3–5) using the Pittsburgh CPC scale.

Results:Patients with favorable neurological outcomes consistently showed higher NPi values (P < 0.001) and greater percentage changes in pupillary diameter (P < 0.001). At 72 hours, the median NPi was significantly higher in the good outcome group (4.7 [interquartile range (IQR), 4.5–4.8] vs. 4.1 [IQR, 3.7–4.5]; P < 0.05). However, NPi values overlapped between groups, and most patients with unfavorable outcomes still exhibited values within the normal range (NPi > 3.0). A receiver operating characteristic analysis of the pupillary percentage change revealed a threshold of 16% to discriminate between the prespecified outcome groups.

Conclusion:Higher NPi values and/or greater pupillary diameter changes of the better reading in bilateral measurements were associated with favorable neurological outcomes after CA. However, previously proposed cutoff thresholds could not be confirmed in our cohort.

Keywords

Automated quantitative pupillometry / Cardiac arrest / Cerebral Performance Category / Infrared pupillometry / Neurological prognostication / Neurological Pupil Index

Conflict of interest statement

The authors declare no conflict of interest.

Author contributions

Marcy F and Schroeder T planned the analysis and contributed to data interpretation, manuscript writing, and review. Storm C assisted with data acquisition, manuscript drafting, and data interpretation. Krannich A was the primary contributor to the statistical analysis. Schueler B supported data acquisition and analysis. Nee J contributed to data interpretation and reviewed the manuscript. All authors reviewed and approved the final manuscript. During the preparation of this work, the authors used ChatGPT (OpenAI) in order to correct grammar and spelling errors. After using this service, the authors reviewed and edited the content as needed and take full responsibility for the content of the publication.

Funding

This research was supported by NeurOptics, Irvine, CA, USA, which provided the pupillometer and disposable SmartGuards used for the measurements. NeurOptics had no involvement in the study design, execution, data analysis, or manuscript preparation. No additional funding was received.

Ethical approval of studies and informed consent

The study was approved by the internal review board (IRB) and ethics committee of Charité University Hospital Berlin (IRB No. EA2/011/15), and was conducted in accordance with the Declaration of Helsinki, as revised in 2013.

Acknowledgments

None.

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