Rebecca Cardigan, BSc, PhD; Sheila Maclennan , MBBS, FRCP, FrCPath

Disclosures

Transfusion Alter Transfusion Med. 2008;10(3):92-101. 

In This Article

Preparation and Storage of Platelet Components

Platelets are transfused to patients who have an inherited or acquired deficiency of platelet number or platelet function.[8] There are two basic methods for producing platelets from whole-blood donations: the 'buffy-coat' method favored in Europe or the platelet-rich plasma (PRP) method favored in North America (Figure 2). Specifications for platelet components are given in Table 4 . In the PRP method, whole blood is separated into PRP and red cells following a 'soft spin'. The PRP is then subjected to a 'hard spin' to remove plasma and concentrate the platelets. In the buffy-coat method, whole blood is subjected to a 'hard spin' and separated into plasma, red cells and a buffy coat that contains most of the platelets but also some leukocytes and red cells. Buffy coats from four to six donations are then pooled with a unit of plasma from one of the donations (or PAS, platelet additive solution), subjected to a 'soft spin' and the PRP removed. The main difference between platelet concentrates collected by apheresis and PRP or buffy-coat platelets is that one or more adult therapeutic doses can be collected by apheresis from a single donor, which is not possible from one whole-blood donation.

For either buffy-coat-derived or apheresis platelets, the majority of plasma (70%) in the platelet concentrate can be replaced with an artificial PAS designed to maintain platelet function during storage. PAS differ in their composition; key elements are the use of acetate or glucose as a substrate for platelet metabolism, phosphate that buffers lactate production, citrate to prevent coagulation and lactate production and the inclusion of potassium and magnesium to improve platelet function during storage. Three different PAS are CE marked in Europe for platelet storage, and some European blood centers routinely produce and store platelets in PAS. Platelets are stored with agitation at 22 ± 2°C for up to 5 days, although in some countries this is extended to 7 days, provided platelets are screened for bacterial contamination. For some patients with severe anaphylactic reactions to platelets because of contaminating plasma proteins, platelets can be re-suspended in 100% additive solution. However, these 'washed' platelets have a reduced shelf life of 24 hours because of the rapid deterioration of platelet quality in the complete absence of plasma, and a proportion of the platelets may be lost during the process.

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