Summary
Transfusion of whole blood and fractionated blood components is a widespread method for managing numerous conditions. Packed RBCs are the most commonly transfused products and are primarily used for the treatment of acute or chronic blood loss. The rationale behind RBC transfusion is not simply to improve the Hb level, but rather to maintain organ perfusion and tissue oxygenation. The decision to transfuse RBCs therefore depends on the Hb level, the patient's hemodynamic status, and comorbidities (e.g., cardiovascular disease). Fresh frozen plasma (FFP) and cryoprecipitate, platelet transfusions, and clotting factor transfusions are also available.
Pretransfusion testing must be performed to prevent the transfusion of incompatible RBCs and subsequent immune hemolytic reactions. The testing involves blood typing of the recipient blood (ABO and Rhesus group), antibody screening of the recipient blood, and compatibility testing (crossmatching recipient plasma and donor RBCs). The most common transfusion reactions are minor allergic reactions (urticaria) and nonhemolytic febrile reactions. However, some transfusion reactions, such as the acute hemolytic transfusion reaction, may be life-threatening and require immediate supportive care. If transfusion reactions do occur, immediate cessation of the transfusion is essential.
Blood group systems
ABO blood type system and Rhesus blood group system
Incidence | ABO antigen on RBCs | Antibodies in plasma | Can receive RBCs from | Can donate RBCs to | Can receive FFP from | Can donate FFP to | |
---|---|---|---|---|---|---|---|
Blood type O | ∼ 45% | No antigens | A and B antibodies | O | O, A, B, AB | O, A, B, AB | O |
Blood type A | ∼ 40% | A antigen | B antibodies | A, O | A, AB | A, AB | A, O |
Blood type B | ∼ 10% | B antigen | A antibodies | B, O | B, AB | B, AB | B, O |
Blood type AB | ∼ 5% | A and B antigens | No A or B antibodies | AB, A, B, O | AB | AB | AB, A, B, O |
Rhesus negative | ∼ 15% | - | Rhesus (Rh) antibodies after previous sensitization | Rh negative | Rh negative, Rh positive | Rh negative, Rh positive | Rh negative, Rh positive |
Rhesus positive | ∼ 85% | - | No Rh antibodies | Rh positive, Rh negative | Rh positive | Rh negative, Rh positive | Rh negative, Rh positive |
Individuals with blood type O negative are “universal donors” of packed RBCs! Individuals with blood type AB positive are “universal recipients” for packed RBCs!
For fresh frozen plasma transfusions, individuals with blood type O are universal recipients (type O plasma contains A and B antibodies) and individuals with blood type AB are universal donors (AB plasma contains no A or B antibodies)!
The universal red cell donor has blood type O. The universal plasma donor has blood type AB.
References:[1]
Pretransfusion testing
Pretransfusion testing must be performed to prevent the transfusion of incompatible blood products and subsequent immune hemolytic transfusion reactions.
-
Procedure
-
Blood typing: ABO and Rh testing of recipient blood
- Hemagglutination: clumping of erythrocytes induced by specific antibodies for erythrocyte antigens
- RBC antibody screening: ABO, D (Rhesus factor), Duffy, Kidd
- Compatibility testing: cross-matching of recipient plasma with potential donor RBCs to test compatibility (indirect Coombs test)
-
Blood typing: ABO and Rh testing of recipient blood
Compatibility testing must be performed before an RBC unit can be released from the blood bank for transfusion!
-
Emergency transfusions
- Transfuse packed RBCs with blood type O
- If needed, fresh frozen plasma (FFP) extracted from blood type AB (Rh positive if possible)
References:[2][3][4]
Transfusion products
Whole blood transfusions
- Content: donor blood or recipient (autologous) blood
-
Indications
- Rarely used except for massive transfusions for significant blood loss
- Elective autologous blood transfusion for elective surgery
Fractionated blood components
Packed red blood cells (RBC)
-
Content: red blood cells
- Leukoreduction; : filtration of blood cells to remove leukocytes to reduce the risk of nonhemolytic febrile transfusion reactions and prevent transmission of CMV, HTLV-I/II, and EBV via leukocytes
- Irradiation: exposure to radiation to inactivate lymphocytes; leukodepleted RBC concentrates are used in immunosuppressed patients to prevent graft-versus-host disease
-
Indications
- Generally to maintain organ perfusion and tissue oxygenation
- Acute hemorrhage; and/or hypovolemic shock (e.g., gastrointestinal bleeding, trauma)
- Symptomatic anemia (e.g., G6PD deficiency, aplastic anemia, β-thalassemia, sickle cell disease, anemia of chronic kidney disease)
-
Situational factors must be evaluated to assess the need for transfusion.
- Extent and cause of anemia
- Clinical findings indicating hypoxia (tachycardia, hypotension, dyspnea)
-
Patient's ability to compensate anemia
- Pre-existing conditions (cardiovascular, pulmonary, malignant)
- Current condition (including prior or planned surgery)
- Age
- For compatibility of RBC transfusions see ABO blood type system and Rhesus blood group system.
The indication for transfusion is not solely dependent on the Hb value, but rather on a combination of clinical findings and pre-existing conditions!
Transfusion thresholds
Transfusion recommendation (American Association of Blood Banks) | ||
---|---|---|
Clinical situation | Hb threshold | Transfusion |
| ≤ 6 g/dL |
|
< 7–8 g/dL |
|
- Effect: 1 unit of packed RBCs increases Hb value approx. 1.0 g/dL
- Complications: Chronic transfusions can lead to hemochromatosis.
Jehovah's Witnesses who do not want to accept blood transfusions should be asked to provide documentary evidence (e.g., advance directive card refusing blood). However, in life-threatening situations in which the patient cannot be consulted, or there is uncertainty concerning the documentation, it is advisable not to withhold blood!
Fresh frozen plasma (FFP)
- Content: plasma; all cellular components have been removed from the transfusion product
-
Indications
- Warfarin overdose
- Clotting factor deficiency (e.g., liver cirrhosis, DIC)
- Substitution of plasma (in the case of massive transfusions)
-
ABO compatibility must be considered.
- According to current guidelines, the Rhesus factor does not have to be considered.
- Lowering the risk of transmitting infections
- Inactivation of viruses
- Quarantine: FFPs are cooled (-30°C) to minimize the risk of HIV and HCV transmission and only released if the donor repeatedly tests negative for HIV and HCV after a quarantine period of 4 months.
- For compatibility of FFP transfusions see ABO blood type system and Rhesus blood group system.
Platelet transfusion
-
Indications
- Thrombocytopenia to prevent spontaneous bleeding
- Massive blood loss
- Effect: One platelet transfusion increases the platelet count by approx. 20–40/nL.
Cryoprecipitate
- Content: clotting factors (fibrinogen, factor VIII, factor XIII), vWF, and fibronectin
- Indications: similar to FFP; preferable if large transfusion volumes are undesirable
Clotting factors
-
Content: specific clotting factors that have been pooled from multiple donors
- E.g., prothrombin complex concentrate
- Indications: specific clotting factor deficiencies, life-threatening bleeds, warfarin overdose
Antithrombin III (AT III)
- Indication:
- In hereditary AT III deficiency to optimize thrombosis prophylaxis with heparin
- In DIC if applicable
- Effect: increases the effects of heparin
- Inhibitor of coagulation, which is synthesized in the liver → inhibition of thrombin, Xa, IXa, XIa, and XIIa
References:[4][5][6][7][8][9][10][11][12]
Transfusion reactions
Clerical errors are the most common cause of transfusion reactions!
Immunologic reactions
Frequency | Pathomechanism | Clinical features | Treatment | |
---|---|---|---|---|
Acute hemolytic transfusion reaction |
|
|
| |
Nonhemolytic febrile transfusion reaction |
|
|
| |
Minor allergic reactions |
|
|
| |
Anaphylaxis |
|
|
| |
Transfusion-related acute lung injury (TRALI) |
|
|
|
|
Post-transfusion purpura |
|
|
| |
Delayed hemolytic transfusion reaction |
|
|
|
If fever develops in a patient receiving a transfusion, repeat donor and patient blood typing and crossmatching to rule out an incompatibility reaction!
Nonimmunologic reactions
-
Transfusion-associated circulatory overload (TACO):
- Definition: fluid overload that can occur with transfusion of blood products . Occurs during or within 6 hours of transfusion.
- Symptoms of hypervolemia: shortness of breath, S3 gallop, jugular venous distention, hypertension
- Chest x-ray shows diffuse bilateral infiltrates as a sign of pulmonary edema
- Treatment: diuretics to correct volume status, oxygen supplementation, assisted ventilation
- Hyperkalemia
- Hypocalcemia: Formation of complexes with the added citrate; occurs with whole blood transfusions, platelet transfusions, or FFP
- Hypothermia
- Sepsis if blood products are contaminated with bacteria
References:[4][6][13][14][15][16][17][18][19][20]