Hemoglobin-based oxygen carriers.

Transfusable fluids that may be used as alternatives to red blood cell transfusion offer the promise of preserving tissue perfusion and minimizing hypoxic cellular damage, and this promise may soon be fulfilled. Clinical testing of hemoglobin-based oxygen carriers has faced and met challenges involving molecular design, safety, efficacy, and regulatory requirements. Three leading candidates have emerged: two human (PolyHeme and HemoLink) and one bovine-based hemoglobin solution (Hemopure). Because a survival benefit has been difficult to demonstrate, avoidance of allogeneic transfusion has been adopted as the standard efficacy end-point for these agents. An update on clinical trial status is provided, and the potential utility of hemoglobin-based oxygen carriers in surgery combined with intraoperative autologous donation is discussed.