Jeffrey McCullough - Transfusion Medicine

During leukapheresis with these instruments, the donor would undergo venipuncture in each arm. Blood was pumped out of one vein and through the blood cell separator, where the granulocytes were removed, and the remaining blood was returned to the other arm. Blood flowed to the bottom of the centrifuge bowl by a central channel, flowed outward along the bottom, and up the sides, where the red cells were packed against the walls. Blood separation occurred in a polycarbonate bowl with a clear plastic cover through which the operator could view the separation of plasma, buffy coat, and platelets. Each of these components was drawn off by a separate peristaltic flow pump adjusted by the operator to maintain optimum cell separation. Although the instrument was designed for granulocyte collection, it was also suitable for platelet collection [16].

Table 6.1 Instruments available in the United States for collection of blood components by apheresis.

Source : Data are from information provided by the manufacturers and Burgstaler EA. Blood component collection by apheresis. J Clin Apher 2006; 21:142–151. © 2006, John Wiley & Sons. Reproduced with permission of John Wiley & Sons.

MNC, mononuclear cell; PBSC, peripheral blood stem cell; RBC, red blood cell.

The key to the instrument was the rotating seal, one section of which was attached to the rotating centrifuge bowl and the other fixed to the blood inflow and outflow lines [17]. The NCI‐IBM Blood Cell Separator contained a blood reservoir so that the donor could be bled intermittently but blood flow into the centrifuge was continuous. The Aminco Celltrifuge was a simpler instrument without the reservoir system, but this necessitated continuous bleeding of the donor. These systems, like the original Latham bowl for plateletpheresis, were very cumbersome because they were made of multiple reusable parts that had to be cleaned, sterilized, and reassembled between procedures. To simplify the procedure and to use more disposable equipment, IBM developed the Model 2997 blood cell separator. In this instrument, the centrifuge bowl was replaced with a disposable hollow plastic blood separation channel attached at both ends to the input and output blood flow ports to form a closed loop [18]. This instrument then formed the basis for the IBM, and later COBE (now Terumo), plateletpheresis instruments.

As the Latham bowl and the Haemonetics system were being developed for plateletpheresis, attempts were made to also use this for granulocyte collection. The intermittent‐flow centrifuge was operated in much the same way as for plateletpheresis, but the operator adjusted the blood flow rates and time of component collection to remove the buffy coat rather than the platelet layer [19–21].

Subsequently a new generation of apheresis instrument technology was developed [22, 23], including a microprocessor to control the operation of the instrument combined with a system that lacked the rotating seal present on the IBM, Celltrifuge, and Haemonetics devices. This system, the Baxter CS‐3000, made possible different types of blood separation because different unique separation chambers were developed for the particular component desired [22, 23]. This system had the additional advantage of being completely closed and enabling sterile collection, and thus storage of products for longer than the 24‐hour limitation.

These three basic instruments—the Haemonetics models, the Gambro (COBE/Terumo) blood cell separator models, and the Baxter CS‐3000—were the mainstay of apheresis for blood component production in the United States for many years, each with certain strengths [24, 25]. Recently, newer apheresis instruments have been developed that allow more 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.

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 × 10 11platelets in 43 minutes [31]. For collection of PBSCs from patient‐donors stimulated by chemotherapy and granulocyte colony‐stimulating factor (G‐CSF), approximately 1.3 × 10 10mononuclear cells (MNCs) and 1.4 × 10 8CD34+ 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 × 10 11platelets, 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.)

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.