Concept of component therapy
Modern transfusiology has almost completely abandoned the use of whole donor blood in favor of component therapy. This approach involves transfusing the patient only with those blood elements they actually need.
There are three main reasons for abandoning whole blood:
- High risk of complications. Whole blood contains a massive array of antigenic factors, provoking severe post-transfusion reactions.
- Lack of target specificity. In specific pathologies (e.g., anemia or thrombocytopenia), a strictly defined pool of cells is required, while ballast components merely overload the bloodstream.
- Economic inefficiency. Splitting a single unit of blood into fractions allows for the rational use of resources and helps multiple patients with different diagnoses simultaneously.
Each component has strict indications. For example, in leukopenia and immunodeficiencies, leukocyte mass is used; in thrombocytopenia, platelet mass; in coagulation disorders or circulating blood volume (CBV) deficits, plasma, protein, or albumin. To correct blood loss and treat anemia, red blood cell mass is indispensable.
Characteristics of red blood cell mass
To obtain red blood cell mass, whole blood undergoes centrifugation or prolonged sedimentation. As a result, 60–65% of the original plasma volume is removed.
The finished medium is characterized by:
- Minimal residual plasma volume.
- Very high red blood cell concentration.
- A hematocrit level within 0.65–0.80.
The product is packaged in glass bottles or special plastic bags. Red blood cell mass must be stored under strict temperature conditions: 4 to 6 °C.
Red blood cell suspension
To improve rheological properties and prolong cell viability, a red blood cell suspension is used. It is a mixture of classic red blood cell mass and a special preservative solution in a strict 1:1 proportion. Sodium citrate acts as the stabilizer in the solution.
Storage conditions for the suspension are identical to the mass (4–6 °C), but the shelf life varies from 8 to 15 days.
Indications for transfusion of mass and suspension:
- Acute blood loss and ongoing bleeding.
- Shock of various origins.
- Severe anemias.
- Blood system disorders.
Frozen red blood cells
This is a special component obtained through complex preliminary processing. Blood undergoes 3–5-fold washing with special solutions followed by centrifugation. The main goal of this stage is the complete removal of leukocytes, platelets, and plasma proteins from the medium.
There are two methods of cryopreservation:
- Slow freezing (in powerful electric freezers at temperatures from -70 to -80 °C).
- Rapid freezing (using liquid nitrogen at a temperature of -196 °C).
In this form, cells can be stored phenomenally long — 8 to 10 years.
The preparation process for transfusion requires care. Thawing is carried out exclusively in a water bath at a temperature of 45 °C, after which the cells are washed free of the protective cryoprotective solution. It is important to remember: after thawing, red blood cells are suitable for use for no more than 1 day (24 hours) when stored at 4 °C.
Advantages and indications for frozen cells
The washing and freezing technology makes this component maximally safe. It is virtually free of sensitizing factors (proteins, leukocytes), coagulation factors, free hemoglobin, serotonin, and potassium.
Who is indicated for native washed or thawed red blood cells:
- Patients with allergic diseases and a history of post-transfusion reactions.
- Patients with confirmed sensitization (especially to plasma proteins or with HLA leukocyte antigen incompatibility).
- In renal and cardiac failure.
- With a high risk of thrombosis and embolism.
- As prevention of massive transfusion syndrome.
- When forced to use blood from a universal donor.
To avoid confusing temperature regimes, remember the "rule of fours": regular mass is stored at 4 °C (up to 6 °C), thawed mass at 4 °C (no more than 24 hours), and it thaws in a bath at a temperature containing the "neighbor" of four — 45 °C.
Class and exam questions
Can red blood cells be frozen at home or in a regular freezer?
No, cryopreservation requires specialized solutions (cryoprotectants) and ultra-low temperatures: from -70 °C in electric freezers to -196 °C in liquid nitrogen.
What is the difference between red blood cell mass and suspension?
Mass is simply condensed red blood cells after removing 60-65% of the plasma. Suspension is the same mass, but diluted with a preservative solution containing a stabilizer (sodium citrate) in a 1:1 ratio.
Why are frozen/washed red blood cells transfused in cardiac or renal failure?
They are purified of free potassium, serotonin, plasma proteins, and coagulation factors, which eliminates toxic load on the myocardium and kidneys, and also reduces the risk of thrombosis.
How long can red blood cells be stored after thawing?
After warming in a water bath (45 °C) and washing, the cells must be used within 24 hours (1 day). Until transfusion, they are kept in a refrigerator at 4 °C.
What else to study on this topic
- Technique of 3–5-fold red blood cell washing
- Mechanisms of HLA antigen system sensitization
- Pathogenesis of massive transfusion syndrome
- Post-transfusion reactions during whole blood transfusion
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Other topics in the section "CHAPTER 6. BLOOD TRANSFUSION"
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