Platelet concentrates prepared in acidified plasma (pH 6.5-6.7) are superior to concentrates prepared by standard methods, and are 80-90 per cent as effective as platelet rich plasma (PRP). The use of excess citric acid to acidify plasma promotes resuspension of the concentrate by eliminating clumping, which is a major factor in the decreased effectiveness of standard concentrates. Analysis of posttransfusion recovery and survival of platelets reveals no evidence of platelet injury in an acid medium.
Acidification of PRP inhibits the aggregation of platelets by adenosine diphosphate (ADP). The presence of endogenous ADP may be an important factor in clumping during standard concentrate preparation.
A method of acidification of PRP using citric acid is described which allows preparation of an effective concentrate from fresh whole blood without subjecting the red cells to acid pH. Reconstitution of the acidified platelet poor plasma and its native red cells increases the citrate molarity by less than 6 per cent and results in minimal decrease in pH of the whole blood.