Platelet Concentrates in an Additive Solution Prepared from Pooled Buffy Coats.

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Abstract
A new method for the preparation of platelet concentrates (PCs) is described. The source material is buffy coat (BC), prepared after keeping standard CPD whole-blood units at room temperature for 6–12 h, followed by centrifugation at 3,500 rpm for 10 min (first series) or 4,000 rpm for 12.5 min (second series). BC, separated from plasma and red cells, was kept at room temperature for a further 8–12 h without agitation. Pools of 6 (first series) and 4 (second series) BCs were prepared using a sterile docking device and suspended in a platelet-additive solution (PAS) containing sodium/potassium chloride, citrate, phosphate, and mannitol. After gentle centrifugation, the platelet-rich supernatant was expressed to and stored in one (first series) or two (second series) 1-liter polyolefine (PL-732) containers. In the first series, the total number of platelets was 316 ± 59 times 109 per PC (yield 65%). However, when the method was applied at a routine scale, the yield varied considerably and was shown to be strongly dependent on the hematocrit of the BCs. A number of steps were taken to standardize the technique which resulted in an improved yield (77.3 ± 8.7%) with 316 ± 52 times 109 platelets (mean ±SD, range 203–490, n = 134), obtained from 4 BC pools and lower leukocyte contamination than before, 18 ±17 times 106 per preparation (range 1–73, microscopic counting, n = 38). The storage medium consisted of a mixture of plasma and PAS. Standardization of the hematocrit and volume of the BCs is essential, both for improvement of the yield and for providing a sufficient amount of glucose and bicarbonate to the platelets throughout storage. The method is particularly suitable in combination with automated techniques for blood component preparation which include BC removal. Blood gases, pH and adenosine triphosphate were maintained at satisfactory levels; the release of platelet factor 4 and lactate dehydrogenase was not different from traditional PC preparation and storage. However, the content of glucose was exhausted in many PC units towards the end of a storage of 6 days. When whole blood and BC are stored for such a long period, and when the gas permeability of their containers is poor, it is important, in order to avoid early loss of swirling, that the surface-to-volume ratio and the gas permeability of the PC containers is sufficiently large to allow good gas exchange.