Over-transfusion with blood for suspected hemorrhagic shock is not associated with worse clinical outcomes

Background: We evaluated patient outcomes after early, small volume red blood cell (RBC) transfusion in the setting of presumed hemorrhagic shock. We hypothesized that transfusion with even small amounts of blood would be associated with more complications. Study design and methods: Retrospective review of trauma patients admitted to a Level 1 trauma center between 2016–2021. Patients predicted to require massive transfusion who survived ≥72 h were categorized according to units of RBCs transfused in the first 24 h. A Cox regression model stratified by dichotomized ISS and adjusted for SBP <90 mm Hg and pulse >120 bpm on arrival was used to estimate hazard ratios (HRs) for outcomes of interest. Results: A total of 3121 (24%) received RBC transfusion within the first 24 h. Massive transfusion protocol (MTP) was activated in 38% (1188/3121): 17% received no RBCs, 27.4% 1–3 units, 32.4% 4–9 units, and 22.7% ≥10 units. Mean ISS increased with each category of RBC transfusion. There was no difference in the risk of acute kidney injury (AKI), acute respiratory distress syndrome (ARDS), infection, cardiac arrest, venous thromboembolism or stroke for patients receiving 1–3 units compared to the non-transfused group or 4–9 units group (p > 0.05). Compared to those receiving ≥10 units, the 1–3 units group had a significantly lower risk of AKI, ARDS, and cardiac arrest. Discussion: Early empiric RBC transfusion for presumed hemorrhagic shock may subject patients to potential over-transfusion and end-organ damage. Among patients meeting clinical triggers for MTP, 1–3 units of allogeneic RBCs is not associated with worse outcomes.