Possible Role of Artificial Oxygen Carriers in Transfusion Medicine: A Retrospective Analysis on the Current Transfusion Practice

Artificial oxygen carriers (AOC) are under development as a substitute for red blood cells (RBC) in homologous transfusion (Tx). The lack of surface antigen in AOC makes ABO-typing and antibody-screening (T/S) unnecessary. Pathogen elimination renders it much safer, and long-term stability allows ubiquitous storage for emergency use. To delineate the utility of AOC, we retrospectively examined current Tx practices in Tokai University and the Japanese Red Cross Society. The emergency department of Tokai University Hospital has been using O(+)Rh(+) RBC in patients with hemorrhagic shock before Tx becomes available. Those who received the RBCs within 60 min of injury had a significantly higher survival rate than those who received it later (>= 60 min). The Red Cross Blood Center provided 411 units of RBC for 138 urgent requests for rare blood types. Our analysis suggests that if an AOC were available for the initial six units, 96% of such requests could have been covered to avoid urgent donor allocation, preparation, and Tx. Among 2079 surgical cases who ordered T/S, only 29% actually required Tx, rendering > 70% of the T/S unnecessary. Because only 7.4% required nine units or more, more than 92% of T/S and Tx could have been avoided in retrospect if an AOC were available for the initial eight units. The results suggest that an AOC might be useful in various situations to alleviate problems, concerns, and technical burden in the current Tx practices. Because the expected utility is based mainly on physical characteristics, AOC may remain advantageous even when biogenetically derived RBC becomes available.