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Citrate is an anticoagulant added to blood products to maintain stability for storage. With the administration of large volumes of blood products, citrate binds to ionized calcium, which can cause hypocalcemia. Evidence for specific calcium administration during massive transfusion protocols is limited; however, a proposed strategy has been to administer calcium gluconate 2 grams for every 2-4 units of red blood cells.
Robinson, et al. performed a retrospective analysis attempting to determine the optimal Citrate:Ca ratio (a novel ratio created for this study) to reduce 30-day mortality. They did not find any differences in mortality; however, they found a Citrate:Ca ratio of 2-3 produced a normalized ionized calcium level with 24 hours of a massive transfusion protocol.
Based on their calculations, this would equate to supplementing 1 g of calcium gluconate for every 3 units of red blood cells given.
***Reminder: Based on the amount of elemental calcium in each gram of calcium gluconate (4.7 mEq) and calcium chloride (13.6 mEq); 3 g calcium gluconate=1 g calcium chloride.***
Bottom Line: Supplementing with calcium gluconate 1 g for every 3 units of red blood cells should be sufficient to maintain normal ionized calcium levels after a massive transfusion protocol.
References
Robinson A, Rech MA, DeChristopher PJ, Vaughn A, Rubino J, Bannister E, Moore ME, Chang K. Defining the optimal calcium repletion dosing in patients requiring activation of massive transfusion protocol. Am J Emerg Med. 2023 May 13;70:96-100.