An earlier class of candidate blood substitutes tried to replace hemoglobin with oxygen-bearing chemicals called perfluorocarbons, widely used in refrigerants a

An earlier class of candidate blood substitutes tried to replace hemoglobin with oxygen-bearing chemicals called perfluorocarbons, widely used in refrigerants and fire extinguishers. One was even approved by the U.S. Food and Drug Administration (FDA) in 1989 for use in surgeries. But the complexities of making and administering it, along with various side effects, undermined that product, which was ultimately withdrawn. I was old enough to remember reading about this in the news when it was still news: https://en.wikipedia.org/wiki/Blood_substitute#Perfluorocarbon_based https://en.wikipedia.org/wiki/Blood_substitute#Perfluorocarb...