BACKGROUND

Frozen red blood cells are important in the military trauma system to maintain blood reserves in challenging operational environments. There are many clinical and operational limitations to using frozen red cells, but they remain an essential capability. However, whole blood is always preferable to using deglycerolized Red Blood Cells (DRBC). The idea behind a frozen blood (DRBC) reserve is twofold in the civilian system: 1.) to freeze units of rare blood types for later use by patients with special transfusion needs and 2.) managing special transfusion circumstances. For the military, the Navy is the primary user of DRBC to meet the needs of isolated maritime operational units with a Food and Drug Administration (FDA) licensed product, provide a licensed product when no other option exists, and for contingency reserves. Glycerol is the additive that is used to protect the RBCs from the effects of freezing. When the blood is thawed, the glycerol is removed, and the product is referred to as DRBC. The introduction of an automated, functionally closed system for glycerolization and deglycerolization of RBCs improved the operational practice and decreases the risk of bacterial contamination of the blood. The first operational frozen blood bank was established in 1956 at Chelsea Naval Hospital (Boston), in part to determine the practicality of frozen blood usage aboard Navy ships. In 1966, under Department of Defense (DoD) direction, the Navy Bureau of Medicine and Surgery established the first frozen blood bank in a combat zone at Naval Station Hospital, DaNang, Republic of South Vietnam. Over a 7-month period, 465 DRBC units were transfused to severely injured casualties. In the 1980s, the DoD froze 68,000 RBC units. Those units were pre-positioned throughout several geographic Combatant Commands in direct support of current and future military medical contingency operations. As of October 2023, just under 950 units of DRBC have been transfused to under 400 casualties. This compares to over 360,000 units of other blood products. (Table 1.) While DRBC have a role in transfusion therapy, they are less commonly used than other blood products and from an operational standpoint, have more of a use on hospital ships and amphibious warships in denied maritime environments. Navy hospital ships (USNS Comfort and USNS Mercy) and amphibious war ships routinely deploy with a standard amount frozen blood reserves roughly proportional to casualty holding capacity (Table 2). Aircraft carriers do not have DRBCs, although some have up to 5 units of stored whole blood generated from the ship’s crew. All the ships in table 2 have a routine walking blood bank (WBB) capability, but no stored platelets.