An exchange transfusion, also known as exsanguination transfusion, replacement transfusion or substitution transfusion, is a blood transfusion in which the patient's blood or components of it are exchanged with or replaced by other blood or blood products.
Most simple blood transfusions involve adding blood or blood products without removing any. A typical example of an exchange transfusion is when apheresis is used to remove the patient's red blood cells or platelets and replace them with cells from blood donors.
Exchange transfusion is used in the treatment of a number of diseases, including sickle-cell disease, thrombotic thrombocytopenic purpura, and hemolytic disease of the newborn. Partial exchange might be required for polycythemia.
Nearly all exchange transfusions are allogeneic (that is, the new blood or blood products come from another person or persons, via donated blood); autologous exchange transfusion is possible (using autologous blood banking), but there are not many situations in which a need for it arises, as most autologous transfusions involve no exchange.
An exchange transfusion requires that the patient's blood can be removed and replaced. In most cases, this involves placing one or more thin tubes, called catheters, into a blood vessel. The exchange transfusion is done in cycles: each one usually lasts a few minutes.
The patient’s blood is slowly withdrawn (usually about 5 to 20 mL at a time, depending on the patient’s size and the severity of illness) and a slightly larger amount of fresh, prewarmed blood or plasma flows into the patient's body. This cycle is repeated until the correct volume of blood has been replaced.
After the exchange transfusion, catheters may be left in place in case the procedure needs to be repeated.
In diseases such as sickle cell anemia, blood is removed and replaced with donor blood.
In conditions such as neonatal polycythemia, a specific amount of the child’s blood is removed and replaced with normal saline, plasma (the clear liquid portion of blood), or an albumin solution. This decreases the total number of red blood cells in the body and makes it easier for blood to flow through the body.
General risks are the same as with any transfusion. Other possible complications include:
- Blood clots
- Changes in blood chemistry (high or low potassium, low calcium, low glucose, change in acid-base balance in the blood )
- Heart and lung problems
- Infection (greatly decreased risk due to careful screening of blood)
- Shock due to inadequate replacement of blood
The patient may need to be monitored for several days in the hospital after the transfusion, but the length of stay generally depends on the condition for which the exchange transfusion was performed.