Blood products

Whole blood transfusion improves the oxygen capacity of the blood, restores volume, coagulation factors and was previously recommended for massive blood loss. However, since component therapy is more effective, whole blood is not currently used for transfusion therapy.

Red blood cell-containing media are the component of choice when it is necessary to increase the hemoglobin level. Indications for transfusion depend on the patient's condition. The oxygen-transport function of blood may be adequate even with a hemoglobin content of 70 g/L in healthy individuals, but transfusions may be necessary at higher hemoglobin levels in patients with pulmonary heart failure or ongoing bleeding. One dose of red blood cell mass increases the hemoglobin level in an adult patient by an average of 10 g/L and the hematocrit level by 3% of the pretransfusion level. When it is necessary to replenish only the blood volume, blood substitutes or blood substitutes in combination with red blood cell mass are usually used. In patients with multiple group antibodies or antibodies to common red blood cell antigens, rarely encountered frozen red blood cell mass is used.

Washed red cells are free of almost all traces of plasma, most white blood cells, and platelets. They are usually given to patients who have had severe reactions to plasma transfusions (e.g., severe allergy, paroxysmal nocturnal hemoglobinuria, or IgA immunization).

In IgA-immunized patients, blood procurement from IgA-deficient donors may be the preferred option.

Leukocyte-depleted red blood cell mass is prepared using special filters that remove £99.99% of leukocytes. It is prescribed to patients with hemolytic febrile transfusion reactions, during exchange transfusions, to patients requiring cytomegalovirus-negative blood when it is not available, and to prevent platelet alloimmunization.

Fresh frozen plasma (FFP) is a non-concentrated source of all coagulation factors except platelets. Indications for its transfusion include correction of bleeding due to plasma factor deficiency when specific factor replacement is unavailable, multifactor deficiency states [eg, massive transfusion, disseminated intravascular coagulation (DIC), liver disease], and warfarin overdose. FFP may be used in addition to packed red blood cells when exchange transfusion is required. FFP transfusions should not be used for simple volume replacement.

Cryoprecipitate is a concentrate prepared from FFP. Each dose of cryoprecipitate typically contains about 80 U of factor VIII, von Willebrand factor, about 250 mg of fibrinogen, and also contains fibronectin and factor XIII. Although cryoprecipitate was originally used to treat hemophilia and von Willebrand disease, it is also used as a source of fibrinogen in acute DIC with bleeding, in the treatment of uremic bleeding, in cardiac surgery (fibrin glue), in obstetric complications such as placental abruption and HELLP syndrome (hemolysis, elevated liver enzymes, and low platelet count), and in factor XIII deficiency. In general, cryoprecipitate should not be used for other indications.

Granulocytes may be transfused in sepsis in patients with severe persistent neutropenia (leukocytes < 500/μl) who have not responded to antibiotic therapy. Granulocytes are used within 24 hours of collection, but the necessary tests (HIV, hepatitis, human T-cell lymphotropic virus, syphilis) may not be completed by this time. Granulocyte transfusions are rarely used because modern antibiotics and drugs that stimulate granulocyte production are used.

Rh immunoglobulin (Rhlg), administered intramuscularly or intravenously, prevents the development of maternal Rh antibodies that may develop during fetomaternal hemorrhage. The standard dose of intramuscular Rhlg (300 mcg) should be given to an Rh-negative mother immediately after abortion or delivery (live or stillborn), unless the child is Rh (D) and D ^u negative or the mother's serum already contains anti-Rh (D). Larger doses of the drug are required if the volume of fetomaternal hemorrhage exceeds 30 ml. If significant hemorrhage is suspected, a rosette test is performed simultaneously with determination of the hemorrhage volume; if it is positive, a quantitative test (e.g., Kleihauer-Bitke) is performed. Rhlg is administered intravenously only if there are contraindications to intramuscular administration (e.g., in patients with coagulopathy).

Platelet concentrate is used to prevent bleeding in asymptomatic thrombocytopenia (platelet level < 10,000/μl); in bleeding with severe thrombocytopenia (platelet level < 50,000/μl); in bleeding in patients with platelet dysfunction caused by antiplatelet agents with a normal platelet level in the blood; in patients receiving massive transfusions causing dilutional thrombocytopenia, and sometimes before surgery, especially with extracorporeal circulation for more than 2 hours (which often leads to platelet dysfunction). One dose of platelet concentrate increases the platelet level by about 10,000/μl. Adequate hemostasis is achieved at a platelet level of about 50,000/μl. Therefore, 4-6 doses of platelet concentrate are usually sufficient for an adult patient.

Platelet concentrate is prepared using automated equipment that collects platelets (or other cells) and returns the unwanted components (e.g., red blood cells, plasma) to the donor. This procedure, called cytapheresis, provides enough platelets from a single donor (equivalent to 6 individual platelet units) to transfuse into an adult patient, thereby minimizing the risk of infectious and immune complications, and is preferable to transfusions from multiple donors.

Some patients may not respond to platelet transfusions, possibly because of splenic sequestration or consumption caused by alloimmunization to HLA or specific platelet antigens. Such patients may respond to transfusions of multiple units of platelet concentrate from different donors (since there is a possibility that some units will be HLA-compatible), to platelet concentrate from a relative, or to ABO- or HLA-compatible platelets. Alloimmunization may be mitigated by transfusion of platelet concentrate or packed red cells after leukocyte depletion.

Irradiation of blood components is used to prevent the risk of graft-versus-host disease.

The use of blood substitutes begins with the use of inert chemical or hemoglobin solutions capable of transporting and delivering O2 to tissues. Perfluorocarbons are chemically and biologically inactive and are capable of dissolving O2 and CO2 under pressure. Since perfluorocarbons are insoluble in water, they are prepared as emulsions. Phase II and III clinical trials are currently underway. Solutions based on the hemoglobin oxygen carrier are in phase III clinical trials in the United States. Chemically modified molecules of human or bovine hemoglobin with the ability to transport O2 are used. These solutions can be stored at room temperature for up to 2 years, making them necessary for use in disaster areas or military operations. However, both drugs (perfluorocarbons and hemoglobin O2 carriers) are eliminated from plasma within 24 hours.

[ 1 ], [ 2 ], [ 3 ], [ 4 ], [ 5 ], [ 6 ]