Alternate cryogens for cryosurgery

There is need for a storable cryogen suitable for use in dermatological cryosurgery as an alternate for the standard nonstorable cryogen now used (liquid nitrogen). Argon gas was tested and found satisfactory, but has not proved to be commercially feasible. Nitrous oxide apparatus is now available but is of limited usefulness. Various freons (fluorinated hydrocarbons) present possibilities for our use. Although they are incapable of producing the degree of cold and depth of penetration attainable with liquid nitrogen apparatus, they can be used to treat the vast majority of lesions now treated by cryosurgery in an office-based dermatological practice. Freons 12, 22 and 13, alone or mixed with other gases, have been tested. Freon 22 seems the most practical for general dermatologic cryosurgery. Although these gases are considered relatively non-toxic, at this time we really do not know their total noxious capabilities.