An organic refrigerant for cryosurgery: fact or fiction?

Dimethylether/propane is an organic substance used as a refrigerant in a new cryodelivery system marketed for the treatment of warts. The objective was first to determine the temperatures achieved by this delivery system, both at the end of the applicator and in the tissues and, second, to compare with liquid nitrogen delivered via standard cryospray equipment (CryAC). Temperature probes were used to measure temperature 1 mm below the epidermis of pig trotters after freezing with the two delivery systems for 20 and 40 s. After freezing with dimethylether/propane, results showed tissue temperatures were 3 degrees C at 20 s and 0 degree C at 40 s. Freezing with liquid nitrogen achieved -20 degrees C at 20 s and -57 degrees C at 40 s. It was concluded that dimethylether/propane does not achieve tissue temperatures below 0 degree C and is not recommended in the use of malignant or premalignant lesions.