Blood transfusion is the process of transferring 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.
Red blood cells (RBC) contain hemoglobin, and supply the cells of the body with oxygen. White blood cells are not commonly used during transfusion, but are part of the immune system, and fight infections. Plasma is the "yellowish" liquid part of blood, which acts as a buffer, and contains proteins and important substances needed for the body's overall health. Platelets are involved in blood clotting, preventing the body from bleeding. Before these components were known, doctors believed that blood was homogenous. Because of this, many patients died because incompatible blood was transferred to them.
Gordon R. Ward, writing in the correspondence columns of the British Medical Journal, proposed the use of blood plasma as a substitute for whole blood and for transfusion purposes as early as 1918. At the onset of World War II, liquid plasma was used in Britain. A large project, known as "Blood for Britain" began in August 1940 to collect blood in New York City hospitals for the export of plasma to Britain. A dried plasma package was developed,[by whom?] which reduced breakage and made transportation, packaging, and storage much simpler.
The resulting dried plasma package came in two tin cans containing 400 mL bottles. One bottle contained enough distilled water to reconstitute the dried plasma contained within the other bottle. In about three minutes, the plasma would be ready to use and could stay fresh for around four hours. Dr. Charles R. Drew was appointed medical supervisor, and he was able to transform the test-tube methods into the first successful technique for mass production.
Another important breakthrough came in 1937–40 when Karl Landsteiner (1868-1943), Alex Wiener, Philip Levine, and R.E. Stetson discovered the Rhesus blood group system, which was found to be the cause of the majority of transfusion reactions up to that time. Three years later, the introduction by J.F. Loutit and Patrick L. Mollison of acid–citrate–dextrose (ACD) solution, which reduced the volume of anticoagulant, permitted transfusions of greater volumes of blood and allowed longer-term
Another important breakthrough came in 1937–40 when Karl Landsteiner (1868-1943), Alex Wiener, Philip Levine, and R.E. Stetson discovered the Rhesus blood group system, which was found to be the cause of the majority of transfusion reactions up to that time. Three years later, the introduction by J.F. Loutit and Patrick L. Mollison of acid–citrate–dextrose (ACD) solution, which reduced the volume of anticoagulant, permitted transfusions of greater volumes of blood and allowed longer-term storage.
Carl Walter and W.P. Murphy Jr. introduced the plastic bag for blood collection in 1950. Replacing breakable glass bottles with durable plastic bags made from PVC allowed for the evolution of a collection system capable of safe and easy preparation of multiple blood components from a single unit of whole blood.
In the field of cancer surgery, the replacement of massive blood-loss became a major problem. The cardiac-arrest rate was high. In 1963 C. Paul Boyan and William S. Howland discovered that the temperature of the blood and the rate of infusion greatly affected survival rates, and introduced blood warming to surgery.
Further extending the shelf-life of stored blood up to 42 days was an anticoagulant preservative, CPDA-1, introduced in 1979, which increased the blood supply and facilitated resource-sharing among blood banks.
As of 2006[update] about 15 million units of blood products were transfused per year in the United States. By 2013 the number had declined to about 11 million units, because of the shift towards laparoscopic surgery and other surgical advances and studies that have shown that many transfusions were unnecessary. For example, the standard of care reduced the amount of blood transfused in one case from 750 to 200 ml.
To ensure the safety of blood transfusion to pediatric patients, hospitals are taking additional precautions to avoid infection and prefer to use specially tested pediatric blood units that are guaranteed negative for Cytomegalovirus. Most guidelines recommend the provision of CMV-negative blood components and not simply leukoreduced components for newborns or low birthweight infants in whom the immune system is not fully developed. These specific requirements place additional restrictions on blood donors who can donate for neonatal use. vnv Neonatal transfusions typically fall into one of two categories:
A massive transfusion protocol is used when significant blood loss is present such as in major trauma, when more than ten units of blood are needed. Packed red blood cells, fresh frozen plasma, and platelets are generally administered. Typically higher ratios of fresh frozen plasma and platelets are given relative to packed red blood cells.
Because blood type O negative is compatible with anyone, it is often overused and in short supply. According to the American Association of Blood Banks, the use of this blood should be restricted to persons with O negative blood, as nothing else is compatible with them, and women who might be pregnant and for whom it would be impossibl
Because blood type O negative is compatible with anyone, it is often overused and in short supply. According to the American Association of Blood Banks, the use of this blood should be restricted to persons with O negative blood, as nothing else is compatible with them, and women who might be pregnant and for whom it would be impossible to do blood group testing before giving them emergency treatment. Whenever possible, the AABB recommends that O negative blood be conserved by using blood type testing to identify a less scarce alternative.
Jehovah's Witnesses object to blood transfusions because of their belief that blood is sacred.
Veterinarians also administer transfusions to other animals. Various species require different levels of testing to ensure a compatible match. For example, cats have 3 known blood types, cattle have 11, dogs have 13, pigs have 16, and horses have 34. However, in many species (especially horses and dogs), cross matching is not required before the first transfusion, as antibodies against non-self cell surface antigens are not expressed constitutively – i.e. the animal has to be sensitized before it will mount an immune response against the transfused blood.
The rare and experimental practice of inter-species blood transfusions is a form of xenograft.