Blood donation

For quite a long time, preserved donor blood was considered the most effective and universal treatment for hemorrhagic anemia, hypovolemic conditions, protein metabolism disorders of various etiologies, etc. Donor blood was widely used during the Great Patriotic War as the only effective treatment for military trauma at that time - acute blood loss. Over time, as highly effective drugs with hemodynamic, rheological, antianemic and hemostatic action were created and introduced into clinical practice, as well as agents that effectively correct protein and water-salt metabolism, the areas of application of donor blood were significantly limited. At present, blood transfusions must be carried out in accordance with the general principles of component hemotherapy: blood transfusions are performed strictly according to indications and with those blood components that the patient's body lacks.

Donor blood: place in therapy

Despite the justified promotion of component hemotherapy, the use of whole blood has its own, albeit limited, indications: in massive blood loss with pronounced hypovolemic shock and anemic hypoxia, decreased BCC (erythrocytes and plasma), massive exchange transfusions (hemolytic disease of the newborn, acute hemolysis, toxicosis, chronic renal failure), especially in military field conditions, disasters, when there is no possibility to immediately obtain a sufficient amount of blood components. In peacetime, especially in planned surgery, when there are indications for hemotransfusion, it is necessary to strictly adhere to the concept of component hemotherapy - to transfuse only the necessary components of donor blood.

The duration of the replacement effect of blood transfusion depends largely on the initial state of the body. It is reduced in feverish conditions, high levels of catabolism in burns, extensive surgical interventions, sepsis, hemolysis and blood coagulation disorders. During transfusion and the next 2-3 days after it, donor blood causes a volemic effect only if the volume of transfused blood does not exceed 20-30% of the BCC and there are no microcirculatory shifts. Blood transfusion exceeding 30-50% of the BCC leads to deterioration of blood circulation, disruption of hemodynamic stability, and pathological deposition of blood.

The autotransfusion method is advisable to use in all cases where transfusion of blood components is indicated to compensate for blood loss and there are no contraindications to blood exfusion in a given patient.

The more pronounced effect of autotransfusions compared to the use of homologous blood can be reduced to the following points:

• higher replacement (antianemic) effect;
• faster postoperative blood recovery due to stimulation of hematopoiesis by repeated preoperative blood donation;
• absence of immunosuppressive effect of transfusion;
• economic effect - reserves of donor homologous blood are preserved.

It is recommended to adhere to two basic rules when deciding on blood transfusion for patients who have received autologous blood:

• It is better not to use preoperative autologous blood (or its components) than to transfuse it to a patient without indications;
• If it is necessary to transfuse large doses of blood components, autologous blood must be transfused first.

The last blood donation should be performed at least 3-4 days before surgery.

A patient can be recommended for autologous donation if two main conditions are met: compensated organ functions (cardiovascular, pulmonary, metabolic, hematopoietic) and exclusion of acute generalized infection, in particular bacteremia/sepsis.

Autoblood is preserved and filtered. If blood or autoerythrocyte mass transfusion is required within 2-3 days after collection, it is recommended to filter the blood through leukocyte filters. Removal of leukocytes is a preventive measure against isosensitization to leukocyte antigens, hemotransmissive viral infections (cytomegaloviruses - CMV), anaphylactic, allergic reactions caused by leukoreagins. For leukofiltration, the most optimal method is to use donor blood collection systems consisting of several interconnected containers with a built-in filter (closed systems).

Preoperative hemodilution - part of the BCC after exfusion of the patient's blood is replaced with blood substitutes to a hematocrit level of 32-35%. The collected donor blood is used to compensate for perioperative bleeding.

Intraoperative hemodilution is the exfusion of blood directly in the operating room after induction of anesthesia with replacement with plasma substitutes to a hematocrit level of at least 30% (in exceptional cases up to 21-22%).

Autoblood, cavity, preserved, filtered for reinfusion (intraoperative autotransfusion, autoblood reinfusion) is most effective where the predicted blood loss may be more than 20% of the BCC. If the blood loss exceeds 25-30% of the BCC, reinfusion should be combined with other methods of autohemotransfusion.

Postoperative autotransfusion is the return of blood to the patient, released through the drains in the immediate postoperative period. Hemolysis not exceeding 2.5 g/l (250 mg/%) of free hemoglobin is safe for blood reinfusion (without washing off the red blood cells). Based on the level of free hemoglobin (should not exceed 2.5 g/l), the number of washing procedures is determined - 1, 2 or 3 times, until a colorless supernatant is obtained. In Cell Saver devices, washing is performed in a bell-shaped rotor automatically with a physiological solution.

At the same time, it is worth keeping in mind that in hospital conditions, with the correct organization of transfusion care in all the listed indications for the use of donor blood and autologous blood, it is more appropriate and justified from a medical and rational from an economic point of view to use blood components. Transfusions of whole preserved blood in a multidisciplinary hospital, especially for patients undergoing elective surgery, must be considered as a result of unsatisfactory work of the transfusion department and blood service.

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Physiological properties of donor blood

Whole preserved donor blood is a heterogeneous polydisperse fluid with suspended formed elements. One unit of preserved donor blood (total volume 510 ml) usually contains 63 ml of preservative and about 450 ml of donor blood. Blood density is 1.056-1.064 for men and 1.051-1.060 for women. Hematocrit of whole preserved blood should be 0.36-0.44 l/l (36-44%). To stabilize blood, a hemopreservative used in the preparation of donor blood or heparin in a physiological solution at a rate of 5 ml per 1 l is most often used.

In adult patients, one volume of 450-500 ml of whole blood increases hemoglobin to approximately 10 g/l or hematocrit to approximately 0.03-0.04 l/l (3-4%).

Unfortunately, none of the known hemopreservatives allows to fully preserve all the properties and functions of blood: oxygen transport, hemostatic, protective-immunological, delivery of nutrients, participation in water-electrolyte and acid-base exchange, elimination of metabolic products, etc. For example, red blood cells can retain the ability to transport oxygen for 5-35 days (depending on the preservative used). During blood transfusions of up to 24 hours of storage, almost all red blood cells immediately start working, providing the body's tissues with oxygen, and when transfusing preserved blood with long storage periods (10 days or more), this function of red blood cells in vivo is restored only after 16-18 hours. In preserved blood, 70-80% of red blood cells remain viable by the last day of storage. As a result of the combined changes, up to 25% of the cellular elements of preserved blood after transfusion are deposited and sequestered in the microcirculatory bed, which makes its use in acute blood loss and anemia inappropriate. A number of the most important biologically active factors of blood plasma that ensure the regulation of hemostasis: VII, VIII, IX, etc., lose their activity in preserved blood after several hours. Some platelets and leukocytes die and disintegrate. At present, donor blood is processed into components within 6 hours - erythrocytes, plasma, platelets and leukocytes and stored under conditions strictly defined for each component: plasma - at -30 ° C, erythrocytes - at 4-8 ° C, platelets - at 22 ° C with constant stirring, leukocytes are recommended to be used immediately (for more details, see the corresponding section of the chapter).

Pharmacokinetics

Single-group donor erythrocytes function in the recipient's body from several days to several weeks after blood transfusion, which is largely determined by the terms and conditions of storage of erythrocytes and the corresponding preservative. Autoerythrocytes are not deposited and circulate in the vascular bed 1.5-2 times longer than donor blood cells.

Contraindications

The main contraindication to transfusion of donor blood and its components (except for special situations, such as for vital indications) is the presence of decompensated pathology of the main organs and systems of the body in the patient:

• acute and subacute infective endocarditis with circulatory decompensation;
• heart defects, myocarditis in the stage of circulatory decompensation;
• pulmonary edema;
• stage III hypertension with severe atherosclerosis of the cerebral vessels;
• miliary and disseminated tuberculosis;
• pulmonary embolism;
• severe liver dysfunction;
• hepatargia;
• progressive diffuse glomerulonephritis;
• renal amyloidosis;
• nephrosclerosis;
• cerebral hemorrhage;
• severe cerebral circulatory disorders.

When determining contraindications to transfusion of preserved blood, it is necessary to proceed from the fact that the patient should not die from unreplaced blood loss, regardless of the pathology he has.

Absolute contraindications to reinfusion of autologous blood are:

• contact of spilled blood with the contents of purulent cavities;
• damage to the hollow organs of the abdominal cavity with contamination of the blood with intestinal or gastric contents, cyst contents, etc.;
• autologous blood remains outside the vascular bed for more than 6-12 hours.

Contraindications to preoperative collection of autologous blood from patients:

• anemia (hemoglobin below 100 g/l, hematocrit <0.3-0.34 l/l);
• leukopenia and thrombocytopenia (leukocytes < 4 x 109/l, platelets < 150 x 109/l);
• hypoproteinemia (total protein below 60 g/l, albumin below 35 g/l);
• hypotension (blood pressure below 100/60 mm Hg);
• cardiovascular decompensation, unstable angina, recent myocardial infarction, ventricular arrhythmia, AV block;
• sepsis, bacteremia, viral diseases, acute inflammatory diseases;
• severe exhaustion and weakness of the patient, adynamia;
• hemolysis of any genesis;
• pregnancy;
• menstruation and the first 5 days after it;
• severe renal impairment with azotemia;
• liver damage with hyperbilirubinemia;
• severe atherosclerosis of the coronary and cerebral vessels;
• patients are under 8 and over 75 years old;
• hemophilia;
• epilepsy;
• hereditary blood diseases (hemoglobinopathies and enzymopathies);
• metastatic cancer;
• thrombosis, thrombophlebitis disease;
• anticoagulant therapy;
• severe form of bronchial asthma;
• severe impairment of liver and kidney function;
• pronounced manifestations (symptoms) or complications of the disease on the day of blood donation.

Contraindications for intraoperative hemodilution generally correspond to contraindications for preoperative autoblood collection.

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Tolerability and side effects

The disadvantages of blood transfusions include, first of all, the real danger of viral, bacterial and parasitic infections, the possibility of infection with serum hepatitis, syphilis, AIDS and other blood-borne infections.

During long-term storage, preserved donor blood loses a number of valuable properties and acquires new qualities that are undesirable for the patient: the potassium content increases, acidosis increases, pH decreases, and the formation and number of microclots increases. One of the severe and dangerous complications of massive transfusions of donor blood is a complex of pathological disorders called homologous blood syndrome. Complications can also occur in the postoperative period. These include delayed anaphylactic reactions, pulmonary distress syndrome, renal and hepatic failure, etc.

Blood transfusion should be treated as a transplant operation with all the consequences that follow from it - possible rejection of cellular and plasma elements of the donor's blood. In patients with immunosuppression, whole blood transfusion is fraught with the development of a dangerous "graft versus host" reaction.

In autodonation, it is necessary to weigh the risk of blood donation each time, even in seriously ill patients, against the risks of allogeneic transfusion. Autodonation may be accompanied by a mild headache, a short-term decrease in blood pressure that does not require treatment; 0.3% of donors experience fainting with a short-term loss of consciousness, and 0.03% experience convulsions, bradycardia, and even cardiac arrest (such as syncope).

Interaction

Autologous blood or donor blood is compatible with other blood components and other medications.

Cautions

Unjustified transfusions of whole blood are not only ineffective, but also often pose a certain danger. In the process of storage, complex biochemical metabolic processes occur in the cells and plasma of preserved blood, which ultimately reduce the quality of the blood and the viability of individual cells. In erythrocytes, the pH decreases, the content of 2,3-DPG, ATP, the affinity of hemoglobin to oxygen increases, platelets and leukocytes are destroyed, hemolysis increases, the concentration of potassium and ammonia ions increases, microaggregates of cellular elements are formed, active thromboplastin and serotonin are released. Changes in the enzyme systems in the cells and plasma lead to the inactivation or distortion of some coagulation factors. Ultimately, the therapeutic effectiveness of preserved blood decreases.

Since over time, stored blood accumulates waste products and cellular decay, donor blood with long shelf lives (< 7-14) is not recommended for use in children, in artificial blood circulation machines, or in vascular surgery.

The storage periods are determined by preservative solutions and the conditions of preparation. Donor blood prepared in plastic bags using a sterile closed system and the preservative CPD (citrate-phoshate-dextrose) is stored at a temperature of +2-6° C for 21 days, when using the preservative CPDA-1 (citrate-phosphate-dextrose-adenine) - 35 days. Violation of the closed circuit of the system or assembly of the system before preparation of blood and its components limits the storage periods of blood to 24 hours at a temperature of +2-6° C. The use of leukofilters built into the closed system of containers does not change the established storage periods of donor blood and its components. The use of leukofilters not built into the system with containers leads to a violation of the integrity of the closed circuit, and in accordance with the instructions, the shelf life of such a medium is reduced to 24 hours.

Transfusion of large volumes of whole blood to achieve a therapeutic effect may result in hypervolemia, cardiovascular overload, isosensitization, and possible changes in the immune system.

Preserved donor blood must meet the following requirements: integrity and tightness of the packaging; presence of a designed label indicating the expiration date and blood group and Rh factor; when left to stand, have a clearly defined boundary separating plasma and cellular mass; plasma must be transparent, without turbidity, flakes, fibrin threads, or pronounced hemolysis; the globular (cellular) layer of blood must be uniform, without irregularities on the surface or visible clots.