Blood Transfusion Therapy

Objectives

This chapter will:

1.
Review the transfusion indications for red blood cells, platelets, plasma, and cryoprecipitate in critically ill patients.
2.
Outline the principles of massive transfusion.
3.
Discuss common transfusion reactions and their management.

Over the last two decades, multiple randomized controlled trials (RCTs) have been conducted to evaluate clinical effects of transfusion in various patient populations. Information gleaned from these clinical trials formed current guidelines for administration of blood components. This chapter will provide a brief update on the evidence-based indications for blood product transfusions as well as its attendant risks.

Blood Components

Whole blood usually is processed into blood components (red blood cells [RBCs], platelets, and plasma) so that each component can be stored at its optimal condition and patients receive only the specific blood components they need. Automatic cell separation (apheresis) technology can also be used to collect RBCs, platelets, and/or plasma. A single apheresis platelets (single-donor platelets) collection or 4 to 5 units of pooled platelets contain sufficient numbers of platelets for a therapeutic dose in an adult patient.

The shelf life of RBC component is determined by the anticoagulant and preservative used; the most commonly used additive solution (ADSOL) allows for up to 42 days of storage at 4°C (1°–6°C) for RBCs. The volume is approximately 350 mL, of which 200 mL is red cells (hematocrit around 60%). In a 70-kg adult, transfusion of one unit RBCs is expected to increase the hemoglobin by 10 g/L or hematocrit by 3%. Platelets are stored at 20° to 24°C with constant agitation for maximum of 5 days. Four to five units of whole blood–derived platelets or one unit of apheresis platelets can increase platelet count by 20 to 40 × 10 ⁹ /L in a 70-kg patient. Fresh frozen plasma (FFP) is frozen and stored at −18°C within 8 hours of collection. It is thawed at 37°C and then stored at 4°C for 24 hours. FFP has a volume of 200 to 250 mL and contains “normal” level of all coagulation factors. Thawed plasma is similar to FFP but can be stored up to 5 days at 1° to 6°C and is clinically interchangeable with FFP. Cryoprecipitate is made from thawing FFP in cold temperature (between 1° and 6°C) and recovering the precipitate. Cryoprecipitate contains fibrinogen (≥150 mg), Factor VIII (≥80 IU), Factor XIII, Von Willebrand factor (vWF), and fibronectin in approximately 5 to 20 mL of plasma; therefore it is a more concentrated source of these coagulation factors than plasma.

Leukocyte-Reduced Blood Components

White blood cells (WBCs) in the blood components can mediate adverse effects. White cells are removed primarily by filtration or apheresis processing. Leukocyte-reduction filters remove 3 to 5 logs (99.9% to 99.999%) of WBCs from whole blood–derived RBCs and platelet components. Leukoreduction can be performed before the component is stored (prestorage leukoreduction) or at the time blood is issued for transfusion (poststorage leukoreduction). Components collected by apheresis technology usually are leukoreduced as part of the collection. The benefits of leukocyte-reduced blood components include: prevention or decrease the incidence of HLA allo-immunization (and platelet refractoriness), reduction of the incidence of febrile nonhemolytic transfusion reactions, and reduction of transfusion-transmitted WBC-associated viruses such as cytomegalovirus (CMV) and Epstein-Barr virus (EBV). Other potential benefits, such as avoiding immunomodulatory effects of transfusion, remain controversial.

Evidence-Based Blood Component Therapy

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