Jeffrey McCullough - Transfusion Medicine

Table 5.3 Some of the products manufactured from whole blood subject to licensure by the US Food and Drug Administration.

AHF, antihemophilic factor; CPD, citrate–phosphate–dextrose.

The beginning of red cell preservation can be traced to Peyton Rous, who was later awarded the Nobel Prize for his work with viruses. Rous [14] and Turner showed that glucose delayed in vitro hemolysis. During the period between World Wars I and II, Mollison [15] in England developed an acidified citrate and glucose solution for red cell preservation, variants of which are the mainstay of present‐day preservatives. These solutions are composed of citrate for anticoagulation, dextrose for cell maintenance, and phosphate buffers ( Table 5.4). WB or RBCs can be stored in these solutions for periods ranging from 21 to 35 days.

During red cell preservation, adenosine triphosphate (ATP) loss generally correlates with poor red cell viability, and addition of adenine at the beginning of preservation increases ATP and improves red cell viability [16]. 2,3‐Diphosphoglycerate (2,3‐DPG) also declines in stored red cells, and this is associated with increased affinity of hemoglobin for oxygen [17–19]. Thus, there was considerable interest in developing solutions that would maintain both ATP and 2,3‐DPG while allowing removal of the maximum volume of plasma for production of derivatives. It is possible to extend the duration of red cell storage by placing the red cells in special “additive” solutions containing various combinations of saline, adenine, phosphate, bicarbonate, glucose, and mannitol [20–23] ( Table 5.5). These solutions provide better nutrients that maintain red cell viability, red cell enzymes, and red cell function, allowing red cell preservation for 42 days ( Table 5.6).

Because most blood is separated into its components, the WB is collected into sets that involve multiple connected bags. The blood first enters the primary bag, where it is mixed with anticoagulant–preservative solution. After collection, the WB is kept at a temperature either between 1°C and 6°C or between 20°C and 24°C depending on the intended use of the unit ( Figure 5.1). If RBCs and plasma are to be produced, the blood is kept between 1°C and 6°C. The blood can be placed in a regular blood storage refrigerator or special insulated containers that contain ice to maintain the 1–6°C temperature. If platelets are to be prepared from the WB, the blood must be maintained at room temperature (20–24°C) because exposure to cold alters the platelets. Maintenance of the blood at room temperature is done by placing the units in containers specially designed to maintain that temperature. It is recognized that the blood will not attain the temperatures of the storage containers (1–6°C or 20–24°C) for several hours, but the blood must be placed in the environment that will begin to bring the temperature of the blood to the desired storage temperature.

Table 5.4 Content of anticoagulant–preservative solutions (mg in 63 mL).

Source : Fung MK, Eder A, Spitalnik SL, Westhoff CM, eds. Technical Manual , 19th edn. Bethesda, MD: American Association of Blood Banks, 2017, p. 132. © 2017 AABB. Reproduced with permission from AABB.

CPD, citrate–phosphate–dextrose; CP2D, citrate–phosphate–double dextrose; CPDA‐1, citrate–phosphate–dextrose adenin‐1.

Figure 5.1 Diagram showing unit of whole blood and integral plastic bag system used for preparing blood components.

High‐speed centrifuges that accommodate four or six units of WB are used to prepare the components. Important factors in the centrifuge techniques include the rotor size, centrifuge speed, time at maximum speed, and braking mechanism or deceleration phase. The WB is manipulated differently depending on the components desired (see later). After removal of the platelet‐rich plasma, the additive solution is added to the concentrated red cells for optimum red cell preservation ( Figure 5.2). Several devices are now available that provide semiautomatic separation of WB. These are in limited use, but the concept has great potential.

Figure 5.2 Diagrammatic illustration of the separation of whole blood into red cells, plasma, and platelet concentrate.

Table 5.5 Content of additive solutions.

Source : Fung MK, Eder A, Spitalnik SL, Westhoff CM, ed. Technical Manual , 19th edn. Bethesda, MD: American Association of Blood Banks, 2017, p. 135. © 2017 AABB. Reproduced with permission from AABB.

NaH 2PO 4, monobasic sodium phosphate; NaCl, sodium chloride; Na 3‐citrate, trisodium citrate.