What is a blood transfusion?
A blood transfusion is used to compensate for a lack of blood or blood components or to replace the blood in the body. For this purpose, blood from plastic bags (blood reserves) is introduced into the patient’s body via a venous access. If this blood comes from a foreign donor, the blood unit is called a foreign blood donation. If the patient receives his or her own blood, which has previously been drawn and stored, it is referred to as autologous blood donation or autotransfusion.
Whereas in the past whole blood transfusions were performed with all components, today blood units are separated into their individual components. This results in:
- red blood cell concentrate – consisting of red blood cells (erythrocytes)
- Granulocyte concentrate – consisting of certain white blood cells (granulocytes)
- Platelet concentrate – consisting of blood platelets (thrombocytes)
- Blood plasma (= non-cellular part of blood)
When do you perform a blood transfusion?
Red blood cell concentrates are mostly used in acute blood loss to replace the lost red blood cells.
Platelet concentrates are also given in cases of high blood loss. In addition, this type of blood transfusion is given for platelet formation disorders and as a bleeding prophylaxis before surgery.
Since blood plasma contains clotting factors that are important for blood clotting, it is also transfused as a preventive measure when bleeding tendencies are suspected.
Granulocyte concentrate can be given as part of a blood transfusion for cancer. The white blood cells (neutrophils, basophils and eosinophils) contained in it are supposed to strengthen the weakened immune system.
What do you do during a blood transfusion?
Before the actual blood transfusion, the doctor will discuss possible risks and side effects with you and determine your blood type. You will also be asked to sign a consent form.
AB0 Blood group system
On red blood cells (erythrocytes) there are protein structures called antigens. Antigens are proteins that trigger an immune response in the body. Carriers with type A antigens have blood type A, and those with type B have blood type B, accordingly. If a person possesses both antigen types, he or she has blood group AB. If there are no antigens on the erythrocytes, one speaks of blood group 0.
In the blood plasma there are antibodies against erythrocyte antigens. So that the immune system does not attack its own body, a person with blood group A, for example, has no antibodies against type A antigens.
Rhesus blood group system
The rhesus blood group system distinguishes whether the blood cells carry a certain protein – the rhesus factor – (rhesus-positive) or not (rhesus-negative). About 85 percent of people in Europe are rhesus-positive, the remaining 15 percent rhesus-negative.
Bedside test
The bedside test is performed on the recipient’s blood as well as on the blood unit intended for use.
Crossmatch
In the crossmatch test, the red blood cells of the blood unit are mixed with the plasma of the recipient (major test) and the red blood cells of the recipient are mixed with the plasma of the blood unit (minor test). Again, agglutination must not occur.
Further procedure
Before the blood transfusion, your patient data are checked again to avoid confusion. The physician will place an access line into the vein through which the blood transfusion is to enter your body. You will be monitored both during the blood transfusion and for at least half an hour afterwards. This includes regular monitoring of your blood pressure and heart rate. If you feel unwell, please tell your doctor immediately.
Further information: Blood Donation
Further information: Donate plasma
If you want to know what you have to consider when donating plasma and how the whole thing works, read the article Donating plasma.
What are the risks of a blood transfusion?
Risks associated with blood transfusions are rare, but usually serious. In a so-called transfusion reaction, the donor’s blood reacts with the recipient’s blood due to incompatibility of blood groups. This causes the immune system to destroy the donor blood, which can lead to fever, anemia, jaundice, circulatory problems and kidney failure. The transfusion reaction may occur directly during the transfusion itself or may be delayed.
Also possible are allergic reactions that manifest as fever, nausea, shortness of breath, drop in blood pressure, redness, itching and, in rare cases, shock.
If a patient receives many red blood cell concentrates, the iron in the red blood cells can be deposited in the organs and cause cell and organ damage. The liver, heart, bone marrow and hormone-producing organs are particularly affected.
What do I have to pay attention to after a blood transfusion?
After an outpatient blood transfusion, you may usually go home. If you notice any discomfort, such as nausea or circulatory problems, you should inform your doctor immediately.
With regular blood transfusions, the success of the therapy is monitored. It is particularly important to measure hemoglobin (red blood pigment) and iron with regard to iron overload caused by the blood transfusion. Side effects do not occur here until the organs are impaired in their function by the overload.
