Page 1922 - Hematology_ Basic Principles and Practice ( PDFDrive )

C H A P T E R 111

PRINCIPLES OF RED BLOOD CELL TRANSFUSION

Yen-Michael S. Hsu, Paul M. Ness, and Melissa M. Cushing

The clinical practice of transfusion medicine has evolved substantially blood component therapy, but the use of fresh whole blood has
since the discovery of the ABO system around 1900. Two technologic persisted in military settings. In the civilian setting, the simultaneous
advances set the stage for clinical practice through blood component need for volume and oxygen-carrying capacity can usually be met by
therapy. First, the introduction of a safe and effective anticoagulant- combining red cells with crystalloid or colloid solutions. In massive
preservative solution (suggested by Loutit and Mollison) allowed for transfusions, however, this clinical axiom is being questioned, and
the preservation of blood products. Second, in the mid-1960s, the current approaches are designed to minimize crystalloid exposure. In
introduction of plastic blood bags by Walter and Murphy, combined some cases of trauma and cardiovascular surgery, platelet transfusion
with the ability to store blood for extended periods, created oppor- may be indicated to combat microvascular bleeding from dilutional
tunities to use transfusions in varied clinical settings. With these thrombocytopenia or bypass-associated platelet dysfunction. The
discoveries, the era of modern component therapy began. In 2011, transfusion of platelets usually supplies the equivalent of several units
approximately 13.8 million units of whole blood/red blood cells of relatively fresh plasma so that there is often no reason for further
(RBC) were transfused in the United States; whole blood transfusions donor exposure by the administration of thawed plasma.
accounted for only 0.15% of total transfusions. This chapter reviews There has been recent renewed interest in fresh whole blood for
appropriate RBC transfusion practice in a variety of clinical settings, patients with severe coagulopathy and shock. Few prospective trials
the clinical implications of RBC storage, the pathogenesis of red cell have compared fresh whole blood with component therapy. The
alloimmunization, and existing and emerging alternatives to alloge- potential advantages for fresh whole blood are a relative increase in
neic RBC transfusions. hemoglobin (Hb) concentration, coagulation factors, and platelets
compared with component therapy. In addition, fresh products avoid
some of the negative effects of storage and processing. A Food and
RED BLOOD CELL COMPONENTS Drug Administration (FDA) approved platelet-sparing leukocyte
reduction filter is available for fresh whole blood. However, the use
Modern transfusion medicine practice aims to provide the specific of fresh whole blood is limited due to the lack of published random-
component of the blood required, rather than whole blood: red cells ized controlled studies on specific indications and the demonstration
for oxygen-carrying capacity, plasma for coagulation proteins, and of significant clinical benefits. The methods to achieve adequate
platelets for microvascular bleeding. The component therapy pathogen removal and the determination of optimal storage condi-
approach allows for optimal use of a limited community resource tions for whole blood products are the subjects of active
(Table 111.1). Today, the clinician wishing to increase the patient’s investigations.
oxygen-carrying capacity is more likely to use an RBC concentrate Increasingly studies in trauma patients have demonstrated a
than whole blood, although there may still be situations in which benefit to the early use of increased ratios of plasma and platelets to
whole blood, if available, is appropriate. For particular clinical RBCs, including the PROPPR study that found there was a signifi-
applications, several modifications can be made to RBC products to cant reduction in the time to hemostasis and a reduction in death by
render them leukocyte or plasma depleted. RBCs can also be frozen exsanguination within 24 hours for patients receiving a 1 : 1 : 1 ratio
for long-term storage. of RBC : plasma : platelets versus a 2 : 1 : 1 ratio. Whole blood transfu-
sion is also being looked at as an alternate approach to provide trauma
patients with early plasma and platelets.
Whole Blood

A unit of whole blood is collected in citrate phosphate dextrose Red Blood Cells
adenine (CPDA)-1 anticoagulant, giving it a shelf-life of 35 days and
a volume of approximately 510 mL (450 mL of blood plus 63 mL RBCs (also referred to as packed RBCs or RBC concentrates) are
of CPDA-1). Within 24 hours of collection, the granulocytes are obtained from anticoagulated whole blood after removal of most of
dysfunctional, and several plasma coagulation factors including the platelet-rich plasma for the production of frozen plasma or
factors V and VIII have fallen. Although clinicians have been taught platelets, or both. At most blood centers, the RBCs are then mixed
that whole blood stored at 4°C has no functional platelets, evolving with 100 mL of an additive nutrient solution that extends the storage
studies have demonstrated in vitro that platelet quantities and func- period to 42 days and results in flow properties similar to those of
tion are maintained for 10–14 days after collection, leading to new whole blood.
interest in the use of whole blood for resuscitation. RBCs are the product of choice for the correction of an isolated
Whole blood has the advantage of correcting simultaneous deficits defect in oxygen-carrying capacity, as in cases of chronic anemia. In
in oxygen-carrying capacity and blood volume. Therefore, whole addition, RBCs rather than whole blood are used for the emergent
blood is useful in the management of trauma or in surgical cases transfusion of patients of unknown ABO type. The use of concen-
involving extensive blood loss. In this setting, whole blood has two trated group O RBCs without plasma containing anti-A and anti-B
distinct advantages: (a) it provides colloid osmotic pressure and can minimize potential hemolysis of the recipient’s red cells.
coagulation factors not supplied by crystalloid solutions and (b) it
does not expose the recipient to RBCs and plasma from different
donors. Leukocyte-Reduced Red Blood Cells
The goal of using whole blood for all cases of concomitant RBC
and volume deficit is difficult to achieve in practice. Most indications Leukocyte-reduced RBCs (LRRCs) can be prepared by a variety of
for whole blood transfusion are now well managed exclusively with methods, resulting in differing degrees of white blood cell (WBC)

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