To Determine the Efficacy of the Modified Shock Index in Predicting the Need for Blood Transfusions in Patients With...

Excessive blood loss remains a major cause of early mortality in trauma patients. Prompt recognition of circulatory failure is crucial for initiating life-saving interventions. However, standard clinical signs, such as heart rate and blood pressure, often remain within normal limits during the initial compensatory phase, thereby masking the early signs of shock. The Shock Index (SI), which is the ratio of heart rate to systolic blood pressure, is widely used to evaluate cardiovascular status; however, it may not accurately reflect tissue perfusion. To improve sensitivity, the Modified Shock Index (MSI) replaces systolic pressure with mean arterial pressure, offering a potentially more accurate measure of hemodynamic compromise.

The aim of our study was to assess the predictive value of MSI for early blood transfusion requirements in polytrauma patients and to evaluate its association with adverse outcomes, including ICU admission, need for mechanical ventilation, and mortality.

This prospective observational study evaluated MSI as a predictor of transfusion requirements and clinical outcomes in 63 polytrauma patients. MSI was calculated at admission, and outcomes, including transfusion >1500 mL, ICU admission, mechanical ventilation, and mortality, were recorded.

The mean MSI at admission was significantly higher in patients who required transfusion volumes greater than 1500 mL. An MSI >1.4 predicted massive transfusions with an AUROC (area under the receiver operating characteristic curve) of 0.890, a sensitivity of 82.5%, and a specificity of 95.65%. Multivariate analysis confirmed MSI > 1.3 as an independent predictor of high transfusion needs (AOR 67.20; p < 0.001). Higher MSI also correlated with adverse outcomes.

The MSI may serve as a simple, non-invasive bedside tool with potential value for early risk stratification in trauma patients. However, given the single-center observational design of this study, these findings demonstrate association rather than causation, and further multicenter studies with larger cohorts are needed to validate these findings and support the integration of MSI thresholds into standardized trauma management guidelines.