Hemospan is a novel polyethylene-modified hemoglobin solution specifically developed to perfuse and oxygenate tissue at risk for ischemia and hypoxia. As a result of the molecular size and oxygen dissociation characteristics, Hemospan selectively off-loads oxygen in tissues predisposed to low oxygen tension. In preclinical studies Hemospan has been found to be free of significant toxicity in a variety of animal species in doses exceeding those that will be used in this study.