Component Preparation and Manufacturing

Whole Blood

WB is the most common starting product for component preparation and manufacturing. WB is generally not found in most transfusion services today because component therapy is more appropriate to target patient’s specific indications for transfusion (e.g., RBC products for symptomatic anemia, plasma products for multiple coagulation factor deficiencies, and platelet products for thrombocytopenia). Additionally, in WB, platelet survival is lost due to refrigerator storage, and coagulation factor activity, especially for labile factors (Factors V and VIII), deteriorates over time. Usually 500 mL of WB is collected into bag with 70 mL of anticoagulant-preservative solution (see below), creating a product with final hematocrit of ∼38%. WB is stored at 1–6°C. Depending on the manufacturer’s system and a country’s regulations, different hold times are allowed before preparation of components from WB. If platelet products are to be manufactured, WB product must be stored at room temperature until the platelets are removed.

Fresh WB is occasionally being used by the US military via “walking blood donors” (donors who are ABO/D typed, infectious disease tested and available to donate in times of need). This product is transfused as soon as possible and has a shelf life of 24 hours when stored at room temperature, allowing maintenance of platelet function, while still minimizing the risk of bacterial overgrowth. Primary use of this product is to infuse viable platelets when other platelet products are not available.

This practice has led to recent use of refrigerated stored WB for civilian trauma and other massive transfusion clinical indications. This product may be leukoreduced using platelet-sparing filter. Additionally, low-titer group O products are being used emergently in trauma patients for initial resuscitation until laboratory-guided (such as Thromboelastography) component therapy can be implemented.

Component Manufacturing

When WB is manufactured into components, it is collected into a primary bag containing an anticoagulant-preservative solution. Primary bag has up to three attached satellite bags for RBC, platelet, and plasma or cryoprecipitate component manufacturing. Because of the different specific gravities of RBCs (1.08–1.09), plasma (1.03–1.04), and platelets (1.023), differential centrifugation of WB unit is used to prepare components. Optimal component separation requires specific centrifugation variables, such as rotor size, speed, and duration of spin ( Fig. 9.1 ). Automated laboratory-based component manufacturing systems are available but not in widespread use in the United States, as they are better suited for buffy coat platelet production.

RBC Components

RBC products are used primarily for the treatment of symptomatic anemia or hemorrhage to increase tissue oxygenation. Anticoagulant-preservative solutions allow RBC components to be stored for extended periods of time at 1–6°C without a significant detrimental effect on RBC quality. Shelf life of given product is determined by solution used and based on criterion that <1% hemolysis in product at the end of storage and 75% of RBCs transfused remain viable 24 hours posttransfusion. RBCs stored in CPD or CP2D have shelf life of 21 days and CPDA-1 of 35 days. RBCs stored in CPD, CP2D, or CPDA-1 have hematocrit of ∼80% with final volume of 225–350 mL and ≤110 mL of plasma. Majority of RBC products are stored in additive solutions.