Transfusion-related acute lung injury (TRALI) is a syndrome that is similar to acute respiratory distress syndrome (ARDS), which develops during or within 6 hours of transfusion of a plasma-containing blood product. Fever, hypotension, shortness of breath, and tachycardia often occurs in this type of reaction. For a definitive diagnosis to be made, symptoms must occur within 6 hours of transfusion, hypoxemia must be present, there must be radiographic evidence of bilateral infiltrates and there must be no evidence of left atrial hypertension (fluid overload). It occurs in 15% of the transfused patient with mortality rate of 5 to 10%. Recipient risk factors includes: end-stage liver disease, sepsis, haematological malignancies, sepsis, and ventilated patients. Antibodies to human neutrophil antigens (HNA)  and human leukocyte antigens (HLA) have been associated with this type of transfusion reaction. Donors antibodies interacting with antigen positive recipient tissue result in release of inflammatory cytokines, resulting in pulmonary capillary leakage. The treatment is supportive. Transfusion associated circulatory overload (TACO) is a common, yet underdiagnosed, reaction to blood product transfusion consisting of the new onset or exacerbation of three of the following within 6 hours of cessation of transfusion: acute respiratory distress, elevated brain natriuretic peptide (BNP), elevated central venous pressure (CVP), evidence of left heart failure, evidence of positive fluid balance, and/or radiographic evidence of pulmonary edema. Transfusion-associated graft versus host disease frequently occurs in immunodeficient patients where recipients body failed to eliminate donors T cells. Instead, donors T cells attack the recipients cells. It occurs one week after transfusion.
The advisory caution to use blood transfusion only with more severe anemia is in part due to evidence that outcomes are worsened if larger amounts are given. One may consider transfusion for people with symptoms of cardiovascular disease such as chest pain or shortness of breath. In cases where patients have low levels of hemoglobin due to iron deficiency, but are cardiovascularly stable, parenteral iron is a preferred option based on both efficacy and safety. Other blood products are given where appropriate, e.g., to treat clotting deficiencies. Procedure
Before a blood transfusion is given, there are many steps taken to ensure quality of the blood products, compatibility, and safety to the recipient. In 2012, a national blood policy was in place in 70% of countries and 69% of countries had specific legislation that covers the safety and quality of blood transfusion. Blood donation
Blood transfusions use as sources of blood either ones own (autologous transfusion), or someone elses (allogeneic or homologous transfusion). The latter is much more common than the former. Using anothers blood must first start with donation of blood. Blood is most commonly donated as whole blood obtained intravenously and mixed with an anticoagulant. In developed countries, donations are usually anonymous to the recipient, but products in a blood bank are always individually traceable through the whole cycle of donation, testing, separation into components, storage, and administration to the recipient. This enables management and investigation of any suspected transfusion related disease transmission or transfusion reaction.