Perfluorochemicals as oxygen transport vehicles.

Perfluorochemical liquids (PFC's) are good solvents for gases and as such, have significant relevance to the field of biology. Approximately 40 ml of oxygen will dissolve in 100 ml of most PFC's, and carbon dioxide is at least twice as soluble. This makes these compounds attractive as vehicles for these and other gases in-vivo and in-vitro. Although many have low viscosities and surface tensions, it is necessary to emulsify them for intravenous use and organ perfusion. The emulsion particles must be very fine, usually about 150 nanometers in diameter, and stable in the presence of blood and other biological fluids. Presently the two most used emulsifying agents are Pluronic F68 and phospholipids. Emulsions made with the former are now known to cause complement activation with accompanying transient decreases in circulating leukocytes and oxygen tension. This phenomenon is reversible and usually not severe. Phospholipid-stabilized PFC emulsions do not activate complement and should therefore, be advantageous. Areas of current research utilizing PFC emulsions are in tumor therapy, by increasing the oxygenation of otherwise hypoxic cells, in ischemic heart treatment, and in alleviating the effects of cerebral ischemia. Many other applications of PFC's are being pursued, and even more research activity in this field is likely.