Hemospan® is a novel hemoglobin-based oxygen carrier developed to perfuse and oxygenate tissue at risk for ischemia and hypoxia. Because of its molecular size and oxygen binding characteristics, Hemospan selectively off-loads oxygen in tissues predisposed to low oxygen tension. Preclinical evidence suggests that Hemospan provides volume expansion and enhances tissue perfusion. Hemospan is therefore being developed as an oxygen-carrying plasma expander for patients where tissues are at risk of inadequate perfusion and oxygenation.~In patients with chronic critical lower limb ischemia (CCLI), the primary cause of ischemic symptoms in the leg is insufficient perfusion. As many of the patients suffering from CCLI are elderly and have concomitant disease, surgical procedures may not always be possible. The goal of all treatments is to improve the blood flow in the nutritional vessels of the ischemic areas; one such possibility may be to use an oxygen-carrying plasma expander.~Hemospan has been shown to improve the oxygenation of tissues by preserving functional capillary density. In addition, Hemospan has a high affinity for oxygen - a feature that is specifically designed to target the unloading of oxygen in the microcirculation where local PO2 levels are much lower (e.g., in ischemic regions). Since Hemospan is a cell-free oxygen carrier, it should be able to perfuse capillaries that are so constricted that red blood cells are unable to flow through them.
The purpose of this study is to evaluate the effects of Hemospan infusion on vascular reactivity, regional perfusion and oxygenation of ischemic tissue in patients with chronic critical lower limb ischemia.