Hemoglobin-based oxygen carriers as resuscitative solutions for trauma and combat casualty care¹

The key beneficial mechanism by which hemoglobin-based oxygen carriers (HBOCs) may be uniquely effective as resuscitative solutions is their ability to enhance oxygen unloading. Animal studies often demonstrate reduced lactates and improved tissue oxygen. On the other hand, vasoconstriction and depressed cardiac output may limit the utility of HBOCs. Polymerization and new formulations may reduce the vasoconstrictive effects compared with tetramer HBOCs, but they do not appear to be eliminated by any formulation. Research in the past decade has indicated that the optimal resuscitation protocol may be the one in which the mean arterial pressure is not fully restored immediately. One problem has been that there is no good animal model for real trauma, which combines blood loss with often both penetrating and blunt injury. Intraoperative models or controlled hemorrhage are probably too simple to serve as useful models to evaluate efficacy and long-term survival after treatment. The clinical need and physical characteristics of HBOCs suggest two different roles for the solutions-correction of anemia, and resuscitation of hypovolemic blood loss. This chapter evaluates the potential role of HBOCs as resuscitative fluids; particularly focusing on the potential use of HBOCs as initial resuscitative solutions for combat casualty care. Specifically, the chapter discusses current strategies for combat casualty care using existing US Food and Drug Administration (FDA)- approved fluids; analyzes HBOC solutions currently under development; and presents some of the data from the HBOC clinical trauma trials and animal studies of hemorrhage.