Dr. Popovsky began the lecture by reviewing several causes of transfusion-associated respiratory distress and then focused on two: Transfusion-related acute lung injury (TRALI) and Transfusion-associated circulatory overload (TACO). As TRALI is recognized as the number one cause of transfusion-related fatalities, TACO is also becoming more recognized. Contrary to prior belief, TACO is a common complication of transfusion, but the frequency is not firmly established. Like TRALI, the reported incidence varies widely.
Dr. Popovsky explained that TACO is not simply the result of transfusing too much blood too quickly; it is now understood to be a more subtle problem that can be difficult to diagnose. The risk factors include patients that are very young or very old. The onset of symptoms occurs in less than two hours of transfusion. Symptoms of TACO include respiratory distress, cyanosis, headache, dry cough; and signs include increased blood pressure and heart rate. Lab findings show an increase in B-natriuretic peptide.
Rapid infusion is a contributing factor for circulatory overload. However, there are few studies as to what constitutes an appropriate infusion rate for blood components, particularly RBCs. Therefore, it is implicated that are 1) need to factor in the recipient's weight, 2) need better quality control of infusion process and pumps, and 3) need data for better nursing guidelines. The prevention of TACO includes the following: 1) evidence-based component therapy, 2) RBC transfusion by the gram of hemoglobin, and 2) standardized RBC dosing.
Dr. Popovsky summarized TACO as follows: 1) TACO is an important clinical diagnosis because it causes significant morbidity and increasing recognition of mortality, 2) It is a frequent complication of transfusion, 3) It is under-recognized and under-diagnosed, and 4) TACO is often confused with TRALI.
TRALI is a syndrome of acute respiratory distress, often associated with fever, non-cardiogenic pulmonary edema, and hypotension and hypertension. Symptoms can range from mild to life-threatening, but most patients recover fully within 96 hours, and the mortality rate is less than 10%.
TRALI is triggered by donor antibodies and biologically active mediators. Donor antibodies are directed toward Human Leukocyte Antigens (HLA) and Human Neutrophil Antigens (HNA). TRALI is associated with plasma products such as Fresh Frozen Plasma (FFP), but can also occur in recipients of Red Blood Cells components. The AABB recommended that blood banks use high plasma volume components from female donors for further manufacturing instead of transfusion due to the higher risk of TRALI.
Prevention (near term) of TRALI includes the following: 1) defer implicated blood donors, 2) avoid the use of plasma from female donors (or screen multiparous donors for anti-HLA), and 3) apply evidence-based use of blood components.
Dr. Popovsky summarized TRALI as follows: 1) TRALI is an important diagnosis, 2) it is frequently confused with TACO, 3) it is under-diagnosed, under-reported, and 4) TRALI represents a spectrum of lung injury (NCPE ® ARDS) and is reversible.