Transfusion reactions

Blood transfusion
Plastic bag with 0.5–0.7 liters containing packed red blood cells in citrate, phosphate, dextrose, and adenine (CPDA) solution
ICD-9-CM	99.0
MeSH	D001803
OPS-301 code	8-80
MedlinePlus	000431
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Blood transfusion is generally the process of receiving blood or blood products into one's circulation intravenously. Transfusions are used for various medical conditions to replace lost components of the blood. Early transfusions used whole blood, but modern medical practice commonly uses only components of the blood, such as red blood cells, white blood cells, plasma, clotting factors, and platelets.

Historically, red blood cell transfusion was considered when the hemoglobin level fell below 100 g/L or falls below 30%. Because each unit of blood given carries risks, a trigger level lower than that at 70 to 80 g/L is now usually used as it has been shown to have better patient outcomes. The administration of a single unit of blood is the standard for hospitalized people who are not bleeding, with this treatment then followed with re-assessment and consideration of symptoms and hemoglobin concentration. Patients with poor oxygen saturation may need more blood. 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 but are cardiovascularly stable, parenteral iron is a preferred option based on both efficacy and safety. Other blood products are given where appropriate, such as clotting deficiencies.

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 62% of countries had specific legislation that covers the safety and quality of blood transfusion.