Data-Driven Re-Evaluation of Hemodynamic Instability in the Pediatric Trauma Population.

BACKGROUND: Hemodynamic instability in pediatric trauma is traditionally defined using reference values derived from healthy children rather than injured patients at risk for mortality. This approach may underestimate true instability and delay life-saving resuscitation. We sought to derive age-specific systolic blood pressure (SBP), heart rate (HR), and shock index (SI) thresholds associated with mortality in pediatric trauma patients. STUDY DESIGN: A retrospective analysis of the American College of Surgeons Trauma Quality Improvement Program (2018-2023) included injured children aged 1-15 years. Discrimination of SBP, HR, and SI for mortality was assessed using the area under the receiver operating characteristic curve, and optimal age-specific thresholds were identified using Youden's index. Derived thresholds were compared with Pediatric Advanced Life Support (PALS) hypotension definitions, age-based tachycardia thresholds, and the Pediatric Age-adjusted Shock Index (SIPA). RESULTS: Among 233,490 pediatric trauma patients, mortality-associated SBP thresholds were consistently 15-30 mmHg higher than PALS hypotension definitions, whereas HR thresholds differed by 0-30 beats/min from traditional age-based values. Derived SI thresholds closely approximated established SIPA values, supporting their validity. The greatest divergence between data-derived and conventional thresholds occurred among children aged 1-2 years. CONCLUSIONS: Mortality in injured children was associated with substantially higher SBP thresholds than those currently used to define hypotension, suggesting that existing pediatric criteria may underestimate hemodynamic instability. The concordance of derived SI thresholds with SIPA provides additional validation of this metric. Adoption of higher SBP thresholds may facilitate earlier recognition of high-risk pediatric trauma patients and more timely resuscitation.