Automated Pupillary Measurements Inversely Correlate With Increased Intracranial Pressure in Pediatric Patients With Acute Brain Injury or Encephalopathy.

Objectives: The purpose of this study was to determine correlation and temporal association between automated pupillary measurements and intracranial pressure in pediatric patients with brain injury or encephalopathy requiring intracranial pressure monitoring. We hypothesized that abnormal pupillary measurements would precede increases in intracranial pressure.
Design: A prospective cohort study was performed. Automated pupillometry measurements were obtained at the same frequency as the patients' neurologic assessments with concurrent measurement of intracranial pressure, for up to 72 hours. Pupillary measurements and the Neurologic Pupil index, an algorithmic score that combines measures of pupillary reactivity, were assessed for correlation with concurrent and future intracranial pressure measurements.
Setting: Single-center pediatric quaternary ICU, from July 2017 to October 2018.
Patients: Pediatric patients 18 years or younger with a diagnosis of acute brain injury or encephalopathy requiring an intracranial pressure monitor.
Interventions: None.
Measurements and Main Results: Twenty-eight patients were analyzed with a total of 1,171 intracranial pressure measurements. When intracranial pressure was elevated, the Neurologic Pupil index, percent change in pupillary size, constriction velocity, and dilation velocity were significantly lower than when intracranial pressure was within normal range (p < 0.001 for all). There were mild to moderate negative correlations between concurrent intracranial pressure and pupillary measurements. However, there was an inconsistent pattern of abnormal pupillary measurements preceding increases in intracranial pressure; some patients had a negative association, while others had a positive relationship or no relationship between Neurologic Pupil index and intracranial pressure.
Conclusions: Our data indicate automated assessments of pupillary reactivity inversely correlate with intracranial pressure, demonstrating that pupillary reactivity decreases as intracranial pressure increases. However, a temporal association in which abnormal pupillary measurements precede increases in intracranial pressure was not consistently observed. This work contributes to limited data available regarding automated pupillometry in neurocritically ill patients, and the even more restricted subset available in pediatrics.