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2386 Part XIII: Transfusion Medicine Chapter 139: Preservation and Clinical Use of Platelets 2387

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PLATELET PRODUCTS AVAILABLE the infectious risk/donor exposure to very low levels. The bacte-
rial risk associated with platelet transfusions is high because plate-
FOR TRANSFUSION lets are stored at 22°C. Some studies suggest a reduction in bacterial
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transmission by transfusion with the use of single-donor platelets.
Platelets are obtained by two different methods: platelet concentrates However, both the American College of Pathologists and the AABB
from whole blood or apheresis platelets. The FDA requires at least 5.5 mandate testing of all platelet products for bacteria, which should
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× 10 platelets/concentrate and 3.0 × 10 platelets/apheresis collection.
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reduce this potential advantage of single-donor platelets. Currently,
the requirement for bacterial testing has increased the use of APs
PLATELET CONCENTRATES FROM because the costs for culture-based testing of an apheresis unit ver-
WHOLE BLOOD sus testing each platelet concentrate that would be used in a pool has
Platelet concentrates can be prepared from units of whole blood using provided a significant cost advantage for APs. As platelet concentrates
are less expensive to produce, this current cost advantage of APs will
two different methods as outlined in Fig. 139–3. These are referred to as likely shift to pooled random donor platelets with more widespread
the platelet-rich plasma (PRP) method, which is used exclusively in the use of prestorage pooling of platelet concentrates allowing bacterial
United States, and the buffy coat (BC) method, which is predomi- testing of the pool. Certainly, there were no differences in post-
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nantly used in Europe and Canada. Comparative studies show no differ- transfusion platelet responses between patients given either pre- or
ence in the quality of these platelet concentrates when they are stored for poststorage pooled platelet concentrates. Although transfusion reac-
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up to 7 days. 56,57 That there are no differences in these products was con- tions may occur less frequently with APs, leukoreduction appears to
firmed in a controlled trial in which the same normal subjects donated mitigate this advantage over pooled platelets. In addition, the use
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whole blood on two occasions. A buffy-coat platelet concentrate or a of leukoreduced pooled random donor platelets does not appear to
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PRP platelet concentrate was randomly assigned to be prepared from lead to increased alloimmunization rates or broaden the specificity of
either the first or second whole-blood donation. After storage for 7 days, any preexisting or developing antibodies compared to leukoreduced
the platelets were radiolabeled and transfused back into their normal single-donor platelets. 42
donor. Recovery differences averaged 3.7 ± 2.4 percent (± SE, p = 0.15)
and survival differences 0.48 ± 0.56 days (p = 0.41).
COMPARATIVE EFFECTIVENESS OF PLATELET-
APHERESIS PLATELETS RICH PLASMA PLATELET CONCENTRATES
The major advantage of AP platelets is that enough platelets can be col- VERSUS APHERESIS PLATELETS, ABO
lected from a single donor to constitute a transfusion dose. In contrast, MATCHING, STORAGE DURATION, AND
to obtain an equivalent number of platelets requires pooling four or five
whole-blood–derived platelet concentrates. ADVERSE EVENTS
The reduction in donor exposures by using AP platelets has the Transfusion Responses
potential advantages of reducing transfusion-transmitted infections Many clinicians consider that platelets obtained by AP give
and the incidence of platelet alloimmunization. However, the current superior posttransfusion platelet responses compared to PRP
tests for detecting viral transmission by transfusion have reduced pooled random-donor whole-blood platelets (rdWBPs). The large

Methods of preparing platelet concentrates Figure 139–3. Preparation of platelet concentrates
from units of whole blood from whole blood. Two methods of preparing platelet
PRP Platelet Concentrate BC platelet concentrate concentrates from whole blood have been developed.
(U.S. system) (European and Canadian systems) The main differences are related to the centrifugation
steps that are used when proceeding from whole blood
to a platelet concentrate. Specific details of the methods
Whole blood Whole blood are described in Slichter and Harker for platelet-rich
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plasma (PRP) method platelet concentrates and Pietersz,
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Soft spin Hard spin Loos, and Reesink for buffy coat (BC) method platelet
concentrates. PPP, platelet-poor plasma.
Remove supernatant PRP to a storage Remove supernatant PPP
bag
Remove BC
Hard spin PRP
Pool 4-6 BC
Remove most of the supernatant PPP
Soft spin
Resuspend packed platelets in residual
plasma
Remove and store supernatant pooled BC
platelet concentrates
Retain and store individual platelet
concentrates or store pre-storage pooled
platelet concentrates

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