Neurological Pupil Index and Outcome After Cardiac Arrest in Children: Single-Center, Retrospective Cohort, 2018–2023

Abstract

OBJECTIVES: To determine the association between abnormal pupillary reactivity using automated infrared pupillometry and unfavorable outcome after pediatric cardiac arrest (CA). DESIGN: Single-center, retrospective, cohort study, 2018-2023. SETTING: Large tertiary PICU in the United States. PATIENTS: We identified 127 patients 18 years old or younger with 8464 pupillary assessments, greater than or equal to 2 measured within 72 hours after return of circulation (ROC). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Abnormal pupillary reactivity was defined as greater than or equal to 2 neurological pupil index (NPi) values less than 3 in either eye. Unfavorable outcome was hospital discharge Pediatric Cerebral Performance Category of 4-6 and increase greater than or equal to 1 from pre-CA status. We explored the diagnostic performance of abnormal NPi for categorizing unfavorable outcome in the first 72 hours post-ROC, and at the time periods of 0-12, 12-24, 24-48, and 48-72 hours. We used a mixed-effects linear regression model to evaluate whether NPi values were associated with favorable vs. unfavorable outcome, after adjusting for clinical variables. Group-based trajectory modeling (GBTM) characterized NPi trajectories over time. Abnormal pupillary reactivity had a sensitivity of 66%, specificity 79%, positive predictive value of 82%, negative predictive value of 63%, and area under the receiver operating characteristic curve of 0.73 (95% CI, 0.65-0.80) for unfavorable outcome. Specificity did not differ between time periods. In the mixed-effects model, unfavorable outcome was associated with lower NPi values that decreased over time (interaction of time from ROC and outcome β = -0.02; p < 0.001). Through GBTM we identified a subgroup of patients with favorable outcome whose NPi was initially abnormal but subsequently improved over time. CONCLUSIONS: In our 2018-2023 experience, the presence of at least two NPi values less than 3 post-CA was associated with unfavorable outcome, with an acceptable level of diagnostic characterization. Of note, some patients with initially lower NPi values improved over time and had favorable outcome.