(1506) Shock Index Predicts Early Blood Transfusion: A Comparative Analysis of Blunt and Penetrating Trauma

Introduction: Shock Index (SI), the ratio of heart rate to systolic blood pressure, was proposed to identify patients in compensated shock. However, studies evaluating its performance in trauma have included patients in decompensated shock for whom the utility of the SI in guiding therapeutic decision-making is low. This study aims to evaluate the performance of SI in trauma patients precisely without severe hypotension and its effectiveness in predicting the need for early blood product administration in patients with blunt or penetrating injuries.

Methods: A retrospective chart review was conducted on adult trauma patients (≥18 years) admitted to a level 1 trauma center between January 2016 and 2023, with initial systolic blood pressure ≥90 mmHg, excluding transfers and pregnant patients. Shock Index was calculated based on arrival vitals, and a logistic regression model was built to predict transfusion within 1 hour controlling for age and injury severity. An AUC curve was drawn to compare blunt and penetrating trauma using model-predicted probabilities.

Results: A total of 1438 trauma patients were included, comprising 208 (14.5%) penetrating and 1230 (85.5%) blunt injuries. The mean shock index was 0.72±0.25, with 163 (11.3%) patients exhibiting an SI >1.0.
Blood product transfusion within 1 hour occurred in 174 (12.1%) patients. The AUC for predicting transfusion within 1 hour was significantly higher in blunt trauma compared to penetrating trauma (AUC 0.87 vs. 0.68, P<.001), with a sensitivity and specificity of 37.1% (30.7-43.8) and 95.0% (94.4-95.5), respectively.

Conclusions: In trauma patients without severe hypotension at presentation, SI demonstrates good discriminatory performance in predicting the need for early blood transfusion. Importantly, its effectiveness differs between blunt and penetrating trauma, with a higher discriminatory performance observed in blunt injuries. These findings highlight the varying utility of the Shock Index in different trauma mechanisms and shock states and emphasize the need for context-specific interpretation when utilizing SI as a prognostic tool in trauma care. These findings have implications for risk stratification and early intervention, potentially guiding the optimization of resource allocation in multi-trauma resuscitations.