t was not until 1957 that Gibson introduced a new anticoagulant, citrate phosphate dextrose (CPD). He concluded that by being less acidic than ACD, it reduced the storage lesion of the red cells and prolonged the expiration date to 28 days.7,8 While this was accepted, a more conservative 21-day expiration date was assigned. Further studies demonstrated that the addition of adenine to the CPD could extend the shelf life of a unit of blood even longer by preventing the fall of ATP levels. The expiration of a unit collected in CPDA-1 is 35 days. Both of these anticoagulants, CPD and CPDA-1, are the standard of today's blood collections throughout the world.
By the 1980s, the introduction of additives extended the length of storage even longer. Currently, three additive solutions are being used: AS-1 (Adsol), AS-3 (Nutricel) and AS-5 (Optisol). The expiration date of the all-additive systems is 42 days. All three contain sodium, dextrose, adenine and mannitol suspended in saline in different concentrations, which add to the survival of the red cells and, at the same time, allow for more plasma to be harvested from a unit of whole blood.