Diethylene Glycol as a Medium for Heat Sterilization of Surgical Instruments *

Since the beginning of aseptic surgery there has been a constant search for a quick and economical means of sterilizing surgical instruments without dulling effect. Heat sterilization in oil, as introduced by Lyman5 in 1917, has proved to be the most satisfactory method thus far, and is widely used in hospitals. There is a definite disadvantage to this procedure, due to the fact that hot oil acts only as dry heat and consequently a high temperature (i.e., 1500 C.) is required for adequate sterilization. This temperature is above the flash-point of most oils, and as a result it is necessary to obtain specially distilled oil with a high flash-point. This is expensive. Recently Gurchot and Mellars3 recommended diethylene glycol as a medium for heat sterilization of instruments. They stated that besides obtaining adequate sterilization in an electric sterilizer, no dulling effect was noticed. Tuckerman' pointed out, however, that there is a constant danger of the temperature rising above the flashpoint of 1300 C., making the apparatus a fire hazard. This difficulty would be eliminated if the heating were to be done in an autoclave where, under steam pressure, a temperature of 120 to 1300 C. can be maintained. Since the work of Koch and Wolffhugel,4 it is well known that moist heat is effective at lower temperatures and in shorter time than is dry heat. The common practice in hospitals of autoclaving with steam under pressure of 18 to 20 pounds for 30 minutes is adequate to kill the most resistant spores, if the moist heat is kept in contact with the organism."0 With this fact in mind, plus the fact that diethylene glycol is completely soluble in water, it seemed likely that diethylene glycol used as a medium in the autoclave would furnish "moist heat" and at the same time protect the sharp instruments from the dulling effect of the steam autoclave. Diethylene glycol is a colorless, odorless, slightly viscid fluid with a sweetish taste which has a freezing-point of 10.45° C., a boiling-point of 244.50 C., heat of vaporization 150 calories per gram, and is freely soluble in water and alcohol. It is insoluble in