Oxygen dissociation after transfusion of blood stored in ACD or CPD solution

In 20 patients undergoing open-heart surgery, 2,3-diphosphoglycerate (2,3-DPG) concentrations, oxygen affinity of hemoglobin (Po2 at half saturation of hemoglobin with oxygen [P50]), hemoglobin concentration, and pH were measured repeatedly. Measurements were made before and at various times after open-heart surgery and replacement of blood loss with blood stored in acid-citrate-dextrose (ACD) or citrate-phosphate-dextrose (CPD) solutions for less than 72 hours (10 cases per group). Infusion of ACD blood caused P50 and 2,3-DPG concentration to decrease significantly after the operation. The infusion of blood stored in CPD did not significantly increase the oxygen affinity. No significant changes in hemoglobin concentration or pH were observed immediately after the operation in either group. To compensate for the increased oxygen affinity, there must be a rise in cardiac output or more likely a decrease in venous Po2. The transfusion of CPD blood, therefore, is more favorable in terms of oxygen supply, particularly in patients who have had cardiac surgery.