Blood transfusion is the process of transferring blood products into a persons 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 they are part of the immune system, and also fight infections. Plasma is the "yellowish" liquid part of blood, which acts as a buffer, and contains proteins and important substances needed for the bodys overall health. Platelets are involved in blood clotting, preventing the body from bleeding. Before these components were known, doctors believed that blood was homogeneous. Because of this scientific misunderstanding, many patients died because of incompatible blood transferred to them. Medical uses
Red cell transfusion
Historically, red blood cell transfusion was considered when the hemoglobin level fell below 100g/L or hematocrit fell below 30%. Because each unit of blood given carries risks, a trigger level lower than that, at 70 to 80g/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 followed with re-assessment and consideration of symptoms and hemoglobin concentration. Patients with poor oxygen saturation may need more blood.
It was the most common procedure performed for patients 45 years of age and older in 2011, and among the top five most common for patients between the ages of 1 and 44 years.According to the New York Times: "Changes in medicine have eliminated the need for millions of blood transfusions, which is good news for patients getting procedures like coronary bypasses and other procedures that once required a lot of blood." And, "Blood bank revenue is falling, and the decline may reach $1.5 billion a year this year [2014] from a high of $5 billion in 2008." Job losses will reach as high as 12,000 within the next three to five years, roughly a quarter of the total in the industry, according to the Red Cross. History
Beginning with William Harveys experiments on the circulation of blood, recorded research into blood transfusion began in the 17th century, with successful experiments in transfusion between animals. However, successive attempts by physicians to transfuse animal blood into humans gave variable, often fatal, results.Pope Innocent VIII is sometimes said to have been given "the worlds first blood transfusion" by his physician Giacomo di San Genesio, who had him drink (by mouth) the blood of three 10-year-old boys. The boys subsequently died. The evidence for this story, however, is unreliable and considered a possible anti-Jewish blood libel. Early attempts
The Incas
The first reported successful blood transfusions were performed by the Incas as early as the 1500s. Spanish conquistadors witnessed blood transfusions when they arrived in the sixteenth century.