A limited number of studies are available on the effect of transfusion on critically bleeding patients. Because it is unethical to conduct RCTs of transfusion versus no transfusion for critically bleeding patients, no Level I or II studies were found. Two prospective cohort (Level III) studies were identified.^91,92 Both assessed the impact of RBC transfusion on in-hospital mortality and acute respiratory distress syndrome (ARDS). One found no difference in risk of in-hospital mortality,⁹¹ whereas the other found a higher risk in patients transfused with more than 10 units.⁹² Because the studies could not control who did or did not receive transfusion, it was not possible to determine whether the risk of death associated with RBC transfusion resulted from the transfusion itself or whether transfusion occurred more often among severely injured patients, whose risk of death was consequently higher. However, multivariate logistic regression analysis to adjust for potential confounders (age, gender, injury type and severity) demonstrated a 4% increased risk of in-hospital mortality per unit of blood transfused in the first 24 hours.⁹² Both studies found an increased risk of ARDS in patients who had received more than 10 units of RBCs. Multivariate logistic regression analysis demonstrated a 4% increased risk of ARDS per unit of blood transfused in the first 24 hours.

Although RBC transfusion can be life saving in critically bleeding patients, the transfusion of RBCs and blood components is associated with potential risks, including infection, acute lung injury, multiorgan failure, systemic inflammatory response syndrome and mortality. As far as possible, exposure to components should be minimised. Use of an MTP is recommended, to coordinate management and guide replacement therapy to minimise transfusion.

Evidence statement

In trauma patients with critical bleeding requiring massive transfusion, an increased volume of transfused red cells may be independently associated with increased mortality.91,92 (See evidence matrix 5 in Appendix E.) In trauma patients with critical bleeding requiring massive transfusion, an increased volume of transfused red cells is independently associated with ARDS.91,92 (See evidence matrix 6 in Appendix E.) = A = B = C = D (See table 2.2)

Practice points