"In addition to the hemoglobin substitutes discussed so far, there is another type of blood substitutes based on perfluorochemicals, synthetic fluids in which oxygen can dissolve. Perfluorochemicals are made into fine emulsions for use as oxygen carriers. Their biggest advantage is that they are synthetic materials and so can be produced in large amounts; also, their purity can be more easily controlled. On the other hand, perfluorochemicals have a much lower capacity for carrying oxygen than does hemoglobin, so the patient must breathe an oxygen-rich air mixture.
"Improved fluorochemicals have recently made it possible to use a higher concentration of perfluorochemicals without causing medical complications. Alliance has developed a blood substitute based on perfluoroctylbromide (C8F17Br) with egg yolk lecithin as the surfactant. The company is now carrying out Phase II clinical trials to delay the need for blood transfusion in surgery, especially when used with autologous blood transfusions (restoring blood previously taken from the patient). At present, the safe volume of blood substitute is limited to 500 to 1,000 milliliters. A group at HemoGen has developed perfluoro-dichoroctane (C8F16Cl2) with triglyceride and egg yolk lecithin as surfactant. One of the potential uses of perfluorochemicals is for those patients whose religious beliefsreligion does not allow them to use donor blood or product prepared from donor blood.
"Further information about blood substitutes is available on the Web from Artificial Cells & Organs Research Centre."