This paper was presented at the 23rd Annual Scientific Assembly of the Eastern Association for the Surgery of Trauma.

Frequently, the need for massive transfusion in major trauma patients is apparent as soon as they arrive in the emergency department. Occasionally, the trauma team is surprised when an apparently stable patient catastrophically drops their pressure. This paper attempts to identify an easily calculated parameter to help predict those surprises before they happen.

The shock index (SI) is defined as the heart rate divided by the systolic blood pressure (HR/SBP). Normal values range from 0.5 to 0.7. The authors looked at all blunt trauma victims at their trauma center over a 9 year period who entered the ED with a SBP > 90. There were 8111 of these patients who met these criteria, and 276 required massive transfusion (3.4%), which they defined as 10 or more units of packed cells in 24 hours.

Analysis of their data showed that the risk for massive transfusion doubled with a SI > 0.9, quintupled for SI > 1.1, and was 7 times higher for SI > 1.3. There was some criticism for using only blunt trauma patients and for the authors’ definition of massive transfusion, but their data appeared to be sound.

The bottom line: the easily calculated Shock Index (HR/SBP) reliably predicts the need for massive transfusion in blunt trauma patients. It is probably valid for penetrating injury as well, but this was not addressed in the current paper.

Reference: Identifying Risk for Massive Transfusion in the Relatively Normotensive Patient: Utility of the Prehospital Shock Index. Vandromme, Griffin, Kerby, McGwin, Rue, Weinberg. University of Alabama at Birmingham.