convenient collection of different combinations of red cells, plasma, or platelets. The principle of each instrument will be described briefly.
Pertinent comments about collection of each component are given next. For details of the operation of the instrument and collection procedure, the manufacturer’s instructions and the references should be consulted.
6.1 Apheresis instruments
Fresenius Kabi Amicus Separator
The Amicus Separator operates using a separation chamber and a separate component collection chamber (Figure 6.1). The centrifuge chamber design contributes to the fluid dynamics and component separation efficiency. Platelet‐rich plasma is continuously elutriated from the separation chamber, followed by further separation into plasma and platelets in the collection chamber. The Amicus Separator can be used to collect platelets [26–28], PBSCs [29], or a combination of red cells, platelets, and plasma [30]. It can also be used to perform therapeutic apheresis procedures, such as therapeutic plasma exchange, RBC exchange, and photopheresis. In plateletpheresis, the Amicus Separator produces about 3.5 × 1011 platelets in 43 minutes [31]. For collection of PBSCs from patient‐donors stimulated by chemotherapy and granulocyte colony‐stimulating factor (G‐CSF), approximately 1.3 × 1010 mononuclear cells (MNCs) and 1.4 × 108 CD34+ cells can be obtained from an 8‐L blood processing procedure [32]. When concurrent red cells, platelets, and plasma are collected, the procedure produces 198 mL of red cells, 3.9 × 1011 platelets, and 198 mL of plasma in 74 minutes [30]. The red cells can be stored the usual 42 days when they are resuspended in the additive solution AS‐1 (Adsol).
Figure 6.1 Flow pathway and blood separation of the Fresenius Kabi Amicus Separator. Recirculation of plasma within the chamber increases the efficiency of separation. White circles represent red blood cells; dark circles represent platelets. PRBC, packed red blood cells.
(Source: Courtesy of Fresenius Kabi, Inc.)
Fresenius Kabi Alyx
This multiple‐component collection system uses continuous separation with fluid flows controlled by a pneumatic pump system and internal sensors to monitor the weight of blood, fluids, and collection components [31, 33, 34]. The plastic, disposable, rigid‐wall separation chamber and cassette interfaces with the pneumatic pump to control fluid flows. A leukodepletion filter is part of the system, and the instrument automatically adds the red cell preservative. Although separation is continuous, blood flow from the donor is intermittent, with plasma being returned after withdrawal of about 300 mL of whole blood. The Alyx can produce two units of red cells in about 35 minutes [31] or up to four units of plasma in less than 45 minutes. The Alyx can also produce combinations of components, for example, one unit of red cells with up to three units of plasma.
Terumo Trima Accel
The Trima Accel can be used for collection of platelets, plasma, or red cells in various combinations [27, 35–39] with a single‐needle technique. The Trima Accel takes about 51 minutes to produce 3.5 × 1011 platelets [27]. Platelets are leukoreduced using an in‐line chamber during the collection procedure. Red cells, platelets, and plasma collected using the Trima Accel have satisfactory in vitro characteristics, in vivo survivals, and in vivo clinical effectiveness [35–40].
Haemonetics Instruments
The Haemonetics system uses a disposable, transparent Lucite centrifuge bowl for blood separation [9]. After venipuncture is performed and the donor is connected to the instrument, the operator activates the instrument and blood is pumped from the donor into the centrifuge bowl (Figure 6.2). Anticoagulant–citrate–dextrose anticoagulant is added to the blood as it leaves the donor. The centrifuge bowl spins at approximately 4,800 rpm and continuously separates the blood as it enters the bowl. When the volume of blood removed from the donor exceeds the capacity of the bowl, plasma begins to exit the bowl and is collected in a bag. The platelet/buffy coat layer accumulates at the top of the red cells, and as the bowl continues to fill, this layer moves toward the exit port. When the platelets—visible as a white band between the red cells and plasma—reach the exit port, a valve is activated, diverting the flow pathway into a separate bag, where the platelets are collected. When the platelets have been collected, the blood flow is stopped, the pumps reversed, and the plasma and red cells recombined and returned to the donor. This cycle of filling the centrifuge bowl is repeated several times to obtain the desired platelet yield.
Figure 6.2 Flow pathway and blood separation in the Haemonetics Latham bowl system.
(Source:Courtesy of Haemonetics Corporation)
The Haemonetics Multiple Component Systems (MCS and MCS+) have the flexibility to collect various combinations of platelets, plasma, and red cells [41, 42] (Table 6.1). The MCS and MCS+ can collect approximately 4 × 1011 platelets in 90 minutes [41, 42]. A combination of platelets and plasma can also be collected [43]. This exciting approach was finally the first step to provide flexibility to the donor center to determine on a daily basis or for individual donors the particular mix of components to collect.
6.2 Plateletpheresis
Single‐donor platelet concentrates
The official US Food and Drug Administration name of this component is platelets, pheresis. In daily practice, this component is usually called single‐donor platelets or plateletpheresis concentrates, a suspension of platelets in plasma or additive solution prepared by cytapheresis.
The use of apheresis, particularly for platelet production, is increasing substantially in many countries [44]. In 1982, about 80,000 plateletpheresis procedures were performed [45] in the United States, and by 2013, this had increased to 2,000,000 [46]. This accounted for about 90% of all platelets produced [46].
Platelets obtained by plateletpheresis are processed, tested, and labeled in a similar manner to whole blood (see Chapters 5 and 7). This includes ABO and Rh typing and testing for all required transfusion‐transmitted diseases. The number of platelets contained in each concentrate is determined, although this information may not necessarily be recorded on the label. Each platelet concentrate has a volume of approximately 200 mL and contains very few red cells (<0.5 mL), and so red cell crossmatching is not necessary. Quality‐control tests must show that at least 90% of the apheresis platelet concentrates produced by each facility contain 3 × 1011 platelets or more [47]. The white blood cell (WBC) content varies depending on the instrument and technique used for collection, but presently all plateletpheresis procedures produce leukodepleted platelets (<1 × 106 WBCs).
Function and storage of platelets obtained by apheresis
Platelets collected using these plateletpheresis systems have in vitro function and in vivo survival characteristics equal to platelets prepared from whole blood [10, 23, 36, 39, 48–52]. The platelets survived normally when autologous transfusions of radiolabeled platelets were given to normal research donors, and platelets collected by apheresis