Abstract
The metabolic and respiratory components of the hydrogen ion content of A.C.D. blood was directly measured by in vitro titration at controlled partial pressures of carbon dioxide. Blood stored for periods of up to 20 days had a mean pH of 6·53. The mean metabolic hydrogen ion excess was 37 mEq/litre and the mean respiratory hydrogen ion excess (carbonic acid) was 98 mEq/litre. The pH and hydrogen ion excess were not significantly related to duration of storage. Both metabolic and respiratory acidosis may occur in recipients of these hydrogen ion loads. In addition, sodium citrate in A.C.D. solution is metabolized in vivo to sodium bicarbonate. Clinically, a variable state of acid-base imbalance may result from the transfusion of A.C.D. blood until homeostasis is restored by renal and respiratory excretion of the acid and base loads.