Replacement and transport effects
The first thing that happens during a blood transfusion is substitution (replacement) action. The transfused fluid rapidly replenishes the lost circulating blood volume, which is critical for stabilizing and restoring normal hemodynamics after blood loss. Along with plasma, vital components enter the recipient's body: nutrients, enzymes, and hormones.
Immediately following volume replenishment, the transport mechanism comes into play. Donor erythrocytes take over the function of carrying oxygen to tissues, eliminating hypoxia. It is important to note that transfused red blood cells remain functionally active and are capable of binding $O_2$ for a long time (up to one month). In addition, adequate transport of various tissue metabolites is restored.
Hemostatic and stimulating action
Donor blood can significantly increase the clotting capacity of the recipient's blood. This hemostatic effect is indispensable for pronounced coagulation disorders and is used in the following conditions:
- Acute bleeding of various origins.
- Hemophilia.
- Cholemia.
- Hemorrhagic diathesis.
The mechanism of bleeding arrest is based on the direct administration of ready-made clotting factors. However, the effectiveness of this process directly depends on the "age" of the preparation: the strongest hemostatic effect is exerted exclusively by fresh blood or material whose storage period does not exceed a few days. Simultaneously with stopping the bleeding, the stimulating effect manifests—general metabolic processes are activated in the patient's body.
Combating intoxication (detoxification)
In severe conditions, transfused blood helps the body cleanse itself. This effect is not uniform, but consists of a whole complex of mechanisms:
- Hemodilution (dilution): by increasing the total fluid volume in the bloodstream, the concentration of circulating toxins is physically reduced.
- Absorption: formed elements and specific proteins of donor blood are capable of absorbing and binding toxic substances on their surface.
- Oxygenation: improved oxygen transport stimulates the oxidation processes of toxic products, converting them into less dangerous forms.
- Transport elimination: the bound poison is transported to the main excretory and detoxification organs (primarily the liver and kidneys) for final destruction and elimination from the body.
Immunobiological and immunocorrective influence
Since blood is living tissue, its administration provides powerful support to the immune system. Donor leukocytes retain their phagocytic activity for a long time after the procedure.
Immunocorrection affects both arms of defense:
- Cellular immunity: provided through the administration of functional neutrophils (capable of bacterial phagocytosis) and lymphocytes (T and B cells).
- Humoral immunity: stimulated by infusing protective factors dissolved in plasma, such as immunoglobulins and interferons.
Due to such a diverse and complex mechanism of action, blood transfusion finds wide application not only in surgical practice, but also in the treatment of infectious and therapeutic diseases.
Briefly: answers to topical questions
Which blood clotting factors are rapidly destroyed during storage of donor blood and require the transfusion of fresh blood?
During the storage of donor blood, hemostasis factors in general are the least stable, although specific destroyed factors are not detailed in the sources. To achieve a hemostatic effect and full administration of clotting factors, the transfusion of fresh blood or blood with a short storage period is required. The storage period of preserved blood for stopping bleeding should be no more than 2–3 days.
What are the absolute contraindications to blood transfusion?
Contraindications to blood transfusion include:
- cardiac decompensation in valvular heart disease, myocarditis, myocardiosclerosis;
- septic endocarditis;
- stage III hypertension;
- cerebrovascular accident;
- thromboembolic disease;
- pulmonary edema;
- acute glomerulonephritis;
- severe hepatic impairment;
- generalized amyloidosis;
- allergic state;
- bronchial asthma.
In the presence of absolute vital indications—shock, acute blood loss, severe anemia, ongoing bleeding, or severe traumatic surgery—blood transfusion is performed despite contraindications.
What post-transfusion complications can occur when incompatible blood is transfused?
When incompatible blood is transfused, an alloimmune hemolytic disease develops, accompanied by massive lysis and agglutination of erythrocytes.
Possible post-transfusion complications include:
- Transfusion reaction—a severe condition up to the development of shock;
- Acute tubular necrosis—pigmentary necrosis due to hemolysis and hemoglobinuria;
- Jaundice—a consequence of erythrocyte destruction;
- Tissue damage—occurs as a result of immune complex deposition;
- General symptoms—fever, malaise, weakness, chills, headache, pruritus, and angioedema.
To memorize the main effects, use the phrase: "Replaced volume, delivered oxygen (transport), clotted the wound (hemostasis), killed toxins (detoxification), and protected immunity."
Class and exam questions
Why is blood transfusion called transplantation?
Because donor blood is a living tissue containing active cells (erythrocytes, leukocytes, lymphocytes). During transfusion, they continue to function in the recipient's body.
Which blood is best suited for stopping bleeding?
To achieve the maximum hemostatic effect, fresh blood or preparations stored for no more than a few days are required, since clotting factors are fully preserved in them.
How does transfused blood fight toxins?
It dilutes their concentration, binds toxins with its proteins, oxidizes them due to the influx of oxygen, and delivers them to the liver and kidneys for excretion.
What else to study on this topic
- Features of replacement therapy in massive blood loss
- Specifics of the use of clotting factors in hemophilia and cholemia
- Mechanisms of toxin binding by plasma proteins (absorption)
- Life cycle and activity of T and B lymphocytes after blood transfusion
- The role of donor interferons and immunoglobulins in humoral immunity
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Other topics in the section "CHAPTER 6. BLOOD TRANSFUSION"
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