Emulsions of perfluorinated solvents for intravascular gas transport

During the past several years we have progressed from the use of perfluorinated substances, which were good gas solvents but often produced unexpected physiological reactions, to a point where emulsions of pure perfluorinated substances can be made in a reproducible way. A standardized method of making emulsions has now been developed. The physical properties of the perfluorinated substances needed to make useful emulsions have been defined. Specifically, perfluorinated substances having vapor pressures above about 40 torr must be avoided as they produce pulmonary gas embolism; also lower boiling components having vapor pressures above about 40 torr must be excluded. The relationship between chemical structure and several physiological and pharmacological effects has been delineated. Perfluorinated substances containing only carbon and fluorine, or those containing carbon, fluorine, and either bromine or iodine have reasonably short dwell times in the liver. Perfluorinated iodo- and bromo-compounds dissolve oxygen and are radiopaque. Present iodo-perfluorinates are unstable in the presence of light. Perfluorodecalin can enter and leave the liver without changing the liver's ultrastructure. Both egg phospholipid and Pluronic F68 are useful in making perfluorodecalin emulsions. Perfluorodimethyladamantane makes a fine-particle stable emulsion. There is a bright future for perfluorinated substances in a number of areas of research in biology and medicine.