Concentrated perfluorooctylbromide emulsion infusion increases tissue PO₂ in normovolemic cats breathing 100% oxygen

Perfluorocarbon liquids have been proposed for decades as artificial blood substitutes because of their ability to dissolve large amounts of oxygen. Until very recently, perfluorocarbon emulsions such as Fluosol-DA (Green Cross, Japan) contained only ten volume percent perfluorocarbon, which only approximately doubles the oxygen solubility compared to plasma. A new emulsion, Oxygent, (Alliance Pharmaceutical, San Diego), with a perfluorooctylbromide (C₈F₁₇Br, PFOB) concentration of about 50 volume percent, is now available. With this increased oxygen solubility, one might expect that this new generation of perfluorocarbon emulsions would be able to supply more oxygen to tissues. It is somewhat surprising that although perfluorocarbon emulsions have been studied as artificial oxygen carriers for almost 25 years, relatively few measurements of tissue oxygen tension (PO₂) have been made. We attempted to discover the experimental conditions under which a variant of Oxygent containing 52 volume percent emulsion (Alliance Pharmaceutical) enhances tissue oxygen delivery. Retinal tissue PO₂ was measured polarographically in the preretinal vitreous humor in anesthetized, artificially respirated, dark-adapted, normovolemic cats, before, during and after the infusion of 1 ml/kg doses of PFOB emulsion. The emusion was always infused while the cats were breathing room air. There was little immediate effect of the infusion on the tissue PO₂ during air breathing, but the change in tissue PO₂ during 100% oxygen breathing episodes increased 60 ± 30% (mean ± SD, n = 8, p = 0.001) with 1 ml/kg and approximately doubled following 3 ml/kg PFOB emulsion. Infusion of the emulsifying medium alone, without the PFOB particles, had negligible effect. These results suggest that PFOB emulsion may be clinically useful in treating tissue hypoxia in normovolemic patients breathing oxygen-enriched air.