The use of the Shock Index as a predictor of active bleeding in trauma patients

Vital signs indicate the presence of bleeding only after large amounts of blood have been lost, with high morbidity and mortality. The Shock Index (SI) is a hemorrhage indicator with a cut-off point for the risk of bleeding at 0.9. The aim of this study is to assess whether a cut-off of≥0.8 is more sensitive for detecting occult bleeding, providing for early initiation of therapeutic maneuvers.

SI analytical validation study of severe trauma patients older than 16 years of age. Vital signs were recorded, and scales for predicting bleeding included: SI, Assessment of Blood Consumption score, and Pulse Rate Over Pressure score. The relationship between the SI and 5 markers for bleeding was analyzed: need for massive transfusion, angiographic embolization, surgical bleeding control, death due to hypovolemic shock, and the overall predictor «active bleeding» (defined as the presence of at least one of the 4 markers above).

Data from 1.402 trauma patients were collected prospectively over a period of 10 years. The mean Injury Severity Score was 20.9 (SD 15.8). The mortality rate was 10%. The mean SI was 0.73 (SD 0.29). «Active bleeding» was present in 18.7% of patients. The SI area under the ROC curve for «active bleeding» was 0.749.

An SI cut-off point≥0.8 is more sensitive than≥0.9 and allows for earlier initiation of resuscitation maneuvers in patients with occult active bleeding.