1-18. ANTICOAGULANT PRESERVATIVES
a. CPD and CPDA-1.
(1) Citrate phosphate dextrose (CPD) is an anticoagulant-preservative
approved by the FDA for 21-day storage of red blood cells maintained at 1C to 6C.
Blood collected in CPDA-1 may be stored for up to 35 days at 1C to 6C. Maintenance
of ATP levels correlates with viability during storage. The low storage temperature, 1C
to 6C, slows glycolytic activity enough that the dextrose substrate is not rapidly
consumed, and intermediary metabolites that may inhibit glycolysis are not generated
excessively. CPD contains enough dextrose to support continuing ATP generation by
glycolytic pathways. The added adenine in CPDA-1 provides a substrate from which
red cells can synthesize ATP during storage, resulting in improved viability when
compared with CPD without adenine.
(2) The quantity of citrate in CPD and CPDA-1 solutions is more than
sufficient to bind the ionized calcium present in the volume of whole blood for which the
bag is designed. Citrate prevents coagulation by inhibiting the several calcium-
dependent steps of the coagulation cascade. Additionally, it retards glycolysis. The
amount of anticoagulant-preservative in commercially available containers is suitable for
450 ml plus or minus 10 percent of blood that is, 405 to 495 ml).
(3) Currently approved by the FDA for extended storage of red blood cells
are two systems in which a second preservative solution is added for red cell storage in
addition to the anticoagulant solution used for whole blood collection. Both require that
the plasma be separated from the red cells before additional preservative solution is
combined with the red cells. This combination should take place as soon as possible but
no later than 72 hours after phlebotomy.
(a) One system consists of a primary collection bag containing CPD.
To this bag are attached satellite bags, one of which contains 100 ml of additive solution
consisting of saline, dextrose, mannitol, and adenine.
(b) The second system consists of a primary collection bag containing
citrate phosphate double dextrose (CP2D), a CPD solution with additional dextrose. A
satellite bag contains 100 ml of additive solution consisting of saline, dextrose, and
(4) Maximum allowable storage time, referred to as shelf-life, is defined by
the requirement for 70 percent recovery at 24 hours, for example, at least 70 percent of the
transfused cells remain in the recipient's circulation 24 hours after transfusion. Transfused
red blood cells that circulate after 24 hours will have a normal survival curve in the recipient.
Blood collected in CPD may be stored for 21 days. Blood collected in CPDA-1 may be
stored up to 35 days. The additive solution systems, approved only for red cell storage
and not whole blood, permit a 35-day and a 49-day dating period respectively.