ABSTRACT
PROPERTIES OF COLD Cold has interesting anesthetic properties1 that develop when the surface of the skin reaches 5°C. The temperature of the dermis and hypodermis is then 15°C. Even if the skin can withstand this temperature for a long time without any obvious damage, in practice it is unthinkable to use cryoanesthesia alone for a full-face phenol peel. Limited areas can, however, be cooled before applying the acids2 to make the application more bearable, when no other anesthetic is being used. To do this, the practitioner can use 3M cold packs (Figure 33.1) or surgical gloves filled with an aqueous solution mixed with antifreeze (75% water and 25% antifreeze). The skin must not be frozen, of course. Some doctors use a facial anesthetic technique that consists in injecting Klein solution3 cooled to just a few degrees Celsius under the skin of the face. This painful technique does not produce sufficient surface anesthesia, and changes all the parameters of how the phenol penetrates through the skin. The skin itself, as opposed to the subcutaneous tissue, is only partially anesthetized by this type of injection, and the peel is still very painful. It is also impossible to inject this solution in the lips, nose, eyelids, and so forth. Doctors who use lasers are familiar with the Dermacool device: it generates cooled air that can be directed locally using a handpiece. This cooling device is sometimes used for local applications of phenol.
