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Introduction: Increased intracranial pressure (ICP) ≥ 20 mmHg is associated with poor neurologic outcomes in children with traumatic brain injury (TBI). Pupillometry measures pupil size, symmetry, and reactivity by stimulating pupillary constriction via light reflex. Neurologic pupillary index (nPI) is a derived measure of pupil constriction, latency, and velocity. Values range from 0 to 4.9, with abnormal being < 3. Adult studies demonstrate a correlation between refractory increased ICP and low nPI. Our aim was to examine the relationship between ICP and nPI in children. Methods: This prospective observational study was performed in the pediatric intensive care unit (PICU) in a tertiary care children’s hospital that is the region’s Level 1 Trauma Center. Data was collected Dec 2024 to Jun 2025. Inclusion criteria were patients 0-18 years old with TBI and an invasive ICP monitor. Pupil size and nPI measurements were obtained by trained PICU nurses utilizing a pupillometer. The primary outcome was the association the between ICP and nPI, assessed via repeated measures correlation. Results: In our sample of 6 patients, 5 (83%) were male, mean age was 13.0 years (SD 2.8), and mean length of stay was 26.0d (SD 20.8). All patients survived, but one had significant morbidity. 220 ICP measurements and 440 corresponding nPI measurements (one per eye) were obtained. There were 7 (3.2%) ICP measurements ≥ 20 mmHg and 2 (0.5%) nPI values < 3. ICP demonstrated a weak correlation with the right nPI (r=-0.18, p=0.01), but not the left (r=-0.01, p=0.92). No change in nPI was seen following 3% hypertonic saline infusion in either the right pupil (mean change 0.32 SD 0.35, p=0.11) nor the left (mean change -.08 SD 0.50, p=0.74). No correlation was found between ICP and right pupil size (r=0.00, p=0.99) nor the left pupil size (r=0.06, p=0.37). Conclusions: Pupillometry is feasible in children with TBI. In our sample there was no strong correlation between ICP and nPI. However, most ICP measurements were < 20 and most nPI values were >3. Future research should examine a sample with higher prevalence of increase ICP to better elucidate its relationship with nPI.