Blood transfusion is a therapeutic procedure that can be performed either as an intravenous injection of red blood cells (red blood cell concentrate: direct administration of red blood cells into a vein) or as a whole blood donation (all types of blood cells are included). However, whole blood donation is almost no longer used in medicine today.
Indications (areas of application)
- Acute blood loss with hemorrhagic shock – in this condition, if necessary, a so-called massive transfusion is performed, in which a “whole blood volume” of the patient is transfused within 24 hours.Blood transfusions can also be used for less massive bleeding. Whether the transfusion is necessary can be determined by the hemoglobin level. It should be noted here, however, that the lead value differs in men and women.
- Blood formation disorders – in the case of anemia or agranulocytosis (reduction in the number of granulocytes; typical symptoms: Fever, sore throat, inflammatory mucosal changes), the administration of blood transfusions is indicated depending on the clinical picture and hemoglobin level.
Contraindications
If the criteria for transfusion are met, there are no known contraindications to blood transfusion to date.
Before blood transfusion
Compatibility (compatibility).
- In any blood transfusion, it is essential to ensure that the donor and recipient blood are compatible before proceeding. Only blood compatible with the blood group may be transfused, otherwise massive and life-threatening immunologic reactions against the donor blood will occur. On the basis of this, a precise examination of various factors is carried out. Of paramount importance are the AB0 system and the rhesus factor.
- The AB0 system describes the blood group antigens, which are located on the erythrocytes as well as on the leukocytes (white blood cells) and platelets (blood platelets). The blood group antigens A, B and 0 can be distinguished. The blood groups can be derived from these. Whereas in most other blood group systems antibodies against foreign characteristics are formed only after a transfusion and would therefore interfere at the earliest a few days later, when a new transfusion is performed, in the AB0 system such antibodies are present in principle against all AB0 characteristics which the recipient himself does not have. From this it can be deduced that a patient who has blood group “A” and receives a donation of type “B” is at massive risk for a hemolytic reaction. This reaction could theoretically destroy all blood cells.
- If an Rh-negative person is exposed to blood from an Rh-positive donor, he or she may develop Rh antibodies that cause Rh-positive erythrocytes (red blood cells) to be destroyed. This is most common in RH-negative pregnant women who have already given birth to an Rh-positive child and may have developed Rh antibodies. In the subsequent pregnancy with another Rh-positive child, the antibodies can now be transferred to the newborn, if necessary, and lead to severe damage to the child.
Compatibility testing
- To prevent these complications already described, tests are performed in the hospital and other medical facilities to minimize the risk of immunological reaction.
- Bedside test – this test is performed directly at the patient’s bedside to eliminate the possibility of recipient mix-up. Bedside test is performed on a small card on which there are three types of test fields with anti-A, anti-B and anti-D serum. Thus, the blood group can be tested in the AB0 system as well as the rhesus factor. A drop of blood is placed on each of the above mentioned fields and mixed. If the applied blood contains the matching antigen to the serum, the blood agglutinates (clumps). Through this reaction it is possible to visually conclude the blood group. However, it must be understood that the bedside test cannot replace either the blood grouping of the patient or the crossmatch, but only checks the compatibility of the patient’s AB antigens with the blood group of the red cell concentrate.Furthermore, it is of great importance that this test procedure is to be performed exclusively by the transfusing physician himself. Due to this, transfer of this task to others is not possible.The only exception to this rule is when the transfusing physician wishes to teach the bedside test to a colleague. Moreover, it should be noted that the bedside test should only be performed directly at the patient’s bedside.Please note: Crossmatching is more difficult in the presence of heat and cold antibodies due to interference with autoantibodies.
The procedure
In blood transfusion, the primary distinction is whether it is an autotransfusion (autologous blood donation) or a foreign blood donation. However, the patient’s own blood or the patient’s own blood components cannot be obtained by a direct autologous blood donation. It is possible to obtain patient blood via machine autotransfusion (MAT, autologous blood recovery from surgical blood). The combination of different procedures such as MAT, but also acute normovolemic hemodilution (blood collection and replacement by infusion with subsequent re-transfusion into the patient’s bloodstream) can, perioperatively (during the surgical procedure), increase the probability of being able to dispense with foreign blood donations. A prerequisite for a complication-free transfusion is that the injected blood components are compatible (compatible) with the recipient’s blood group. For this reason, the exact verification of compatibility is indispensable and is explicitly regulated. It should also be noted that blood transfusions as a medical measure require the patient’s consent after adequate information. Only in acute justified emergencies is the attending physician permitted to perform a blood transfusion even in the absence of consent. Although artificial blood substitutes and hemoglobin preparations are currently being researched, they have not yet been used in medical therapy. Blood component transfusion
As already described, blood transfusions are no longer performed by administering whole blood, but by administering individual separated blood components. On the one hand, this separation of the individual components ensures that the patient receives only those blood components for which there is a deficiency. On the other hand, component administration is far more economical, as the blood components can be stored for longer. Another problem with whole blood storage is that a constant temperature of +4 ˚C must be maintained for optimal preservation of the blood in order to preserve the integrity of the platelets (thrombocytes) and erythrocytes (red blood cells). However, at this temperature, other components can be damaged, massively reducing the quality of the blood product. The following blood components are transferred:
- Red blood cells (erythrocytes) – the administration of red blood cell concentrates is primarily done in cases of anemia (anemia). The condition of anemia describes a reduction in the oxygen-carrying capacity of the blood due to a reduced red cell count or a reduced hemoglobin concentration.To explain, hemoglobin (blood pigment) is an oxygen-carrying protein in the erythrocyte. In principle, anemia is not a diagnosis, but a finding with multiple causes that must be investigated diagnostically. Different types of anemia can be distinguished, but all of them can subsequently lead to tachycardia (heartbeat too fast: > 100 beats per minute), increased blood pressure amplitude (the margin between the maximum and minimum blood pressure increases) and, if necessary, a feeling of weakness.
- Platelets (blood platelets) – injection of platelet concentrates is performed in patients suffering from thrombocytopenia (platelet deficiency) and thus from an increased tendency to bleed. Possible triggering factors for thrombocytopenia may include hematological diseases such as leukemia (blood cancer) or thrombotic thrombocytopenic purpura (a disease in which a defect in blood flow can cause blood vessels to become blocked). A deficiency condition can also occur during pregnancy, but very rarely leads to the administration of platelets.
- Granulocytes (part of the leukocyte group – white blood cells) – in granulocytopenia (granulocyte deficiency), the defense system is weakened, so infections can occur more easily. Granulocytes are part of the non-specific defense system.
- Blood plasma (liquid component of blood) – in the case of a deficiency of plasma proteins, for example, after large blood losses or bleeding tendency, the administration of plasma is often indicated.
- Blood stem cell preparations – the transfer of blood stem cell preparations usually occurs when a stem cell transplant is performed. However, it is important to distinguish whether the transplant is autologous (donor and recipient are the same person) or allogeneic (donor and recipient are two different people).
- Clotting factors – administration of clotting factor concentrates is performed, for example, in patients with a deficiency of factors VIII and IX. This deficiency leads to marked coagulation disorders known as hemophilia A (VIII deficiency) and B (IX deficiency).