Buffy‐Coat‐Derived Platelet Concentrates Prepared from Half‐Strength Citrate CPD and CPD Whole‐Blood Units: Comparison between Three Additive Solutions: In vitro Studies

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Abstract
The in vitro effects of storage of platelets prepared from 4 or 6 pooled buffy coat (BC) units and stored in a platelet storage medium consisting of 30–40% of CPD plasma or alternatively half-strength citrate CPD (0.5 CPD) plasma and 60–70% of different alternative platelet additive solutions (PASs) were evaluated. Measurements of mean platelet volume, pH, pO2, pCO2, bicarbonate, glucose, lactate, ATP, total adenine nucleotide content, extracellular lactate dehydrogenase or adenylate kinase activity, as markers for disintegration of platelets, and extracellular β-thromboglobulin, as a marker for activation of platelets, were included in the in vitro studies. Previous studies indicated that a reduction of the citrate concentration from the standard 21 to 8 mmol/l is associated with a significant reduction of the consumption of glucose and production of lactate. Alternatively, similar effects can be obtained by the addition of acetate. In a preliminary paired study, the effects of different concentrations of acetate were tested. In an additional paired study, the effects of CPD plasma in combination with either saline or a PAS containing NaCl (115.5 mmol/l), citrate (10 mmol/l), and acetate (30 mmol/l), pH 7.2 (PAS-2) were evaluated. 0.5CPD plasma in combination with either PAS-2 or a nonacetate PAS (PAS-1) were also tested. The storage of platelets in 0.5CPD plasma was used as a reference. The conclusions are: (1) A minimum acetate concentration of 30 mmol/l is needed to counteract the effects of citrate on the production of lactate. (2) pH and the bicarbonate buffering capacity are significantly better maintained in PAS-2 than in PAS-1. With PAS-2, a significantly lower consumption of glucose and a significantly lower production of lactate are also observed. (3) When the storage period exceeds 5 days, PAS-2 is superior to saline as plasma diluent with regard to the maintenance of pH. (4) A significantly lower consumption of glucose was noted in 0.5CPD plasma diluted with PAS-2 as compared to undiluted 0.5CPD plasma. A significantly better maintenance of bicarbonate buffering capacity was also seen. (5) By comparing PAS-2 in combination with either CPD or 0.5CPD, significantly lower values for pCO2 and consumption of glucose were observed with 0.5CPD. The levels of pH and pO2 are significantly higher with 0.5CPD. We conclude that PAS-2 during 9-day storage is associated with the most stable storage conditions with regard to the in vitro variables used in this study. The results suggest that at least 7 days storage of PCs in a medium consisting of 30% of either standard CPD or 0.5CPD plasma and 70% PAS-2 is possible.