Pulmonary edema after transfusion: How to differentiate transfusion-associated circulatory overload from transfusion-related acute lung injury

Objective: Pulmonary edema is an underrecognized and potentially serious complication of blood transfusion. Distinct mechanisms include adverse immune reactions and circulatory overload. The former is associated with increased pulmonary vascular permeability and is commonly referred to as transfusion-related acute lung injury (TRALI). The latter causes hydrostatic pulmonary edema and is commonly referred to as transfusion-associated circulatory overload (TACO). In this review article we searched the National Library of Medicine PubMed database as well as references of retrieved articles and summarized the methods for differentiating between hydrostatic and permeability pulmonary edema. Results: The clinical and radiologic manifestations of TACO and TRALI are similar. Although echocardiography and B-type natriuretic peptide measurements may aid in the differential diagnosis between hydrostatic and permeability pulmonary edema, invasive techniques such as right heart catheterization and the sampling of alveolar fluid protein are sometimes necessary. The diagnostic differentiation is especially difficult in critically ill patients will multiple comorbidities so that the cause of edema may only be determined post hoc based on the clinical course and response to therapy. Guided by available evidence, we present an algorithm for establishing the pretest probability of TRALI as opposed to TACO. The decision to test donor and recipient blood for immunocompatibility may be made on this basis. Conclusions: The distinction between hydrostatic (TACO) and permeability (TRALI) pulmonary edema after transfusion is difficult, in part because the two conditions may coexist. Knowledge of strengths and limitations of different diagnostic techniques is necessary before initiation of complex TRALI workup.