Defining the Super Massive Transfusion in US and Coalition Forces during Combat Operations in Afghanistan and Iraq

Introduction: Hemorrhage is the leading cause of potentially preventable death on the battlefield. After hemorrhage control, the resuscitation with blood products is essential to restore circulating volume and prevent coagulopathy. While massive transfusion (MT) occurs frequently after major trauma, it remains unclear who the subset of casualties is that define a super massive transfusion which would require mobilization of additional resources. We seek to determine what defines a super MT as this would help allocate resources.

Methods: This is a secondary analysis of a previously described dataset from the Department of Defense Trauma Registry. In this analysis, we isolated US and Coalition casualties that received at least 1 unit of packed red cells or whole blood. To describe the super MT, we sought the top quartile of total products administered within the first 24 hours.

Results: Out of the 28222 casualties within our dataset, we identified 2204 US military and 498 Coalition that met inclusion for this analysis. The median number of total products administered within the first 24 hours was 16 with 39 total product units at the 75th percentile, which included 691 casualties. Of those in the super MT group, their median injury severity score was higher (29 versus 18, p<0.001), they were most frequently injured by explosive (84% versus 69%, p<0.001), they had a higher mean emergency department pulse (116 versus 103, p<0.001), lower mean systolic 109 versus 122, p<0.001), and higher mean international normalized ratio (1.53 versus 1.28, p<0.001). They more frequently had serious injuries to the thorax (29% versus 22%, p<0.001), abdomen (32% versus 17%, p<0.001), and extremities (85% versus 64%, p<0.001). Super MT was associated with worse survival (86% versus 92%, p<0.001).

Conclusions: In our dataset, we identified the top 25^th percentile of total product administration within the first 24 hours at 39 total product units. More data is needed to define this population early in their clinical course to better mobile resources early when needed.