Definition
A blood transfusion is the administration of blood or blood components through a vein. The blood used for this purpose is taken from a donor at the time of donation. Whereas in the past blood was given without being separated into its components, nowadays this so-called “whole blood” is separated first.
This produces 3 parts: red blood cells, platelets and the remaining liquid, the blood plasma. This separation makes it possible to give a patient only the blood component he or she needs. Among other things, this reduces the risk of side effects.
What are reasons for a blood transfusion?
The administration of a blood transfusion is indicated at: Blood loss (acute or chronic) e.g. due to surgery or trauma Anaemia (anemia) Blood coagulation disorders Thrombocytopenia (platelet deficiency) In the case of blood coagulation disorders, in contrast to anaemia, no erythrocyte concentrates are administered, but instead the coagulation factors are substituted. Thrombocytopenia is a deficiency of blood platelets. In this case, thrombocyte concentrates are administered. In any case, care must be taken to ensure that the blood groups of the donor and the recipient are compatible. – Blood loss (acute or chronic) e.g. due to surgery or trauma
- Anaemia (lack of blood)
- Blood coagulation disorders
- Thrombocytopenia (blood platelet deficiency)
Reasons for a blood transfusion
The human body basically needs a certain amount of blood to function. Without enough blood, our cells cannot be supplied with enough oxygen and toxic decomposition products accumulate – this ultimately leads to death. If we lose a large amount of blood or if certain blood components are used up too much, part of it has to be replaced by a blood transfusion.
There are many reasons for blood transfusions. Red blood cells, for example, are given in cases of anaemia. This often occurs after major operations (postoperative anaemia) or serious accidents.
Diseases of the gastrointestinal tract, such as ulcerative colitis or various cancers, such as leukaemia, can also lead to anaemia. Malnutrition, kidney diseases, coagulation disorders and diseases of the haematopoietic system in the bone marrow also frequently lead to anaemia. Blood platelet concentrates are usually administered to a patient when the platelets, also called thrombocytes, in the blood drop so much that heavy bleeding can occur.
This is often the case with severe blood loss after an accident, with disorders of blood formation in the context of leukaemia, with side effects of medication, after radiation or with kidney diseases. The reason for the administration of blood plasma is usually a disturbance in blood coagulation. This can occur in liver diseases, congenital diseases or autoimmune diseases.
In the case of anaemia, also called anaemia, the value of haemoglobin in the blood is reduced. Haemoglobin is found in the red blood cells and is necessary to ensure the supply of oxygen to the cells. If the concentration is too low, symptoms such as reduced performance, pale skin, dizziness or shortness of breath occur.
Depending on the cause and extent of the anaemia, it may be necessary to treat it with a blood transfusion. Erythrocyte concentrates are then administered, i.e. a blood product which consists mainly of red blood cells, because they contain hemoglobin. If the anaemia must be treated regularly with transfusions, there is a risk of iron overload.
Red blood cells contain iron and release it when they break down. When transfusions are given, the body therefore also receives a large amount of it, but can only store a small amount. The iron is deposited in organs where it can cause damage.
This should be prevented in frequent blood transfusions, e.g. with iron chelators. Iron deficiency anaemia is one of the most common deficiency diseases in the world. A deficit of iron in the body leads to lowered hemoglobin levels and thus to anaemia.
The most common cause of iron loss is chronic bleeding, e.g. after surgery, trauma, bleeding from the gastrointestinal tract or menstrual bleeding. Usually, therapy is carried out by the oral administration of iron preparations and stopping the source of bleeding. Blood transfusions do not normally need to be given.
However, it may be necessary in cases of severe bleeding. Leukaemia is the cancer of the precursor cells of our blood. No matter what form of leukaemia a person has, the disease often limits blood production to such an extent that a blood transfusion must be given.
The reason for this is usually the migration of cancer cells into the bone marrow, where our blood is produced. If the cancer grows uncontrollably here, it displaces and destroys the healthy, haematopoietic cells and thus causes anaemia. With some forms of leukaemia, such as “chronic lymphatic leukaemia”, it usually takes months or years before a deficiency of red blood cells, platelets or blood plasma develops.
In other forms, however, it can happen very quickly: acute forms of leukaemia can require a blood transfusion within days or weeks. In addition, leukaemias often require chemotherapy. The drugs used for this purpose destroy fast-growing cells – these include cancer cells as well as the healthy cells of the bone marrow that form the blood.
For this reason, a blood transfusion may also be necessary as part of the treatment. The hospital decides when a transfusion has to be carried out and which blood components are required based on the values obtained from a blood sample. Anemia is not a rare side effect in cancer patients.
Especially tumors that affect the blood and hematopoietic system, such as leukemia, are the main causes. However, other types of tumours can also contribute to anaemia by infesting the bone marrow, increasing the decay of red blood cells or even by releasing pro-inflammatory substances. The therapy of a tumour disease can also lead to anaemia.
Chemotherapy or radiation are aggressive procedures that do not leave the body without leaving traces. Blood transfusions cannot cure the cancer, but they can help the affected patients with the symptoms of anaemia and thus restore quality of life. However, there are also risks here.
A blood transfusion is an additional burden on the immune system and in cancer patients who are already immunocompromised anyway, the susceptibility to infection can increase. It must therefore be decided in each individual case whether a blood transfusion is useful for the patient or not. Chemotherapy is an aggressive therapeutic procedure that kills not only the cells of a tumour but also healthy cells.
It therefore also represents an enormous burden for the body. Since both the tumor disease and the chemotherapy can impair blood formation and thus also reduce the hemoglobin, it can make sense to administer a blood transfusion both during and after the chemotherapy. The transfusion does not heal, but merely relieves the symptoms of anaemia.
Especially after chemotherapy, however, the aim should be to restore the body’s own functions, such as blood formation, to a normal level. It must therefore be decided individually how useful a blood transfusion is. Anemia in the newborn is called fetal anemia.
In this case, the children often come into the world very pale. Here too, the cause is a lack of haemoglobin or red blood cells. This deficiency is often triggered by different rhesus factors in mother and child, which causes the mother’s immune system to produce antibodies against the child’s blood cells.
Rhesus prophylaxis can prevent this. In severe cases a blood transfusion is also necessary. This can also be carried out in the womb by means of a cord blood transfusion.
A fatal course of fetal anaemia is rare nowadays. Blood transfusions are relatively often necessary during or after major surgery. The reason for this is usually the loss of blood during the operation or post-operative bleeding in the operated body part.
As it is mainly red blood cells that are lost during a bleeding, so-called “red blood cell concentrates” – concentrates of donated red blood cells – are usually used during the transfusion. Before major operations, during which major blood losses are to be expected, blood preserves are usually prepared in advance for safety reasons. However, due to the risks associated with a blood transfusion, the first step is to replace the lost blood with saline fluids (called infusions).
Only when the blood loss is very high, the blood reserves are used. An important decision factor here is the haemoglobin value, which indicates how much haemoglobin is still in the blood: if it falls below a certain limit, the patient must be given concentrated red cells. After operations, a blood transfusion is usually necessary if there is bleeding within the operation wound. This is often noticed by a lot of blood in the dressing or drains, and sometimes only when symptoms of anaemia, such as paleness or a rapid heartbeat, occur.
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