Use of Oxygen-15-Labeled Molecular Oxygen for Oxygen Delivery Studies of Blood and Blood Substitutes

Abstract

Blood substitutes are being developed as a temporary replacement fluid and oxygen carrier for patients with severe blood loss due to trauma, shock or combat casualty (1,2). These substitutes are not meant to replace blood for they do not have properties bestowed by white blood cells, platelets and other plasma factors. Within the field of blood substitute research, there is a great need for developing techniques to determine the effectiveness of various blood substitutes in relationship to their ability to pick up oxygen as it passes through the lungs or deliver oxygen when it reaches the tissues. These comparisons must be performed to monitor the effectiveness of the various substitutes between each other or as a group against the native oxygen carrier, red blood cells (RBC). For widespread use, these methods to determine effectiveness in relationship to oxygen transport properties must be relatively non-invasive and physiologic, as well as applicable to human patients by being easy to perform in a clinical setting and use non-toxic agents. Moreover, these techniques must be able to distinguish the tissue oxygenation by the blood substitute in the presence of other oxygen carriers, namely RBC. Many techniques including frozen myocardial spectroscopy, microelectrodes, phosphorescence quenching, magnetic resonance spectroscopy, near-infrared spectroscopy, NADH fluorescence and electron spin resonance have been summarized for their usefulness in assessing oxygenation either directly or indirectly by Wagner and Scheid (3).