Body Temperature During Surgery and Anesthesia

The recognition of fulmin ant hyperthermia and accidental hypothermia during anesthesia and surgery has given a new impetus to clinical thermometry in the operating room. It is sugges ted that in order to recognize and avoid these conditions in the anesthetized patient, a routine of continuous monitoring of body temperature be added to our armamentarium fo r patient care. One of the problems that has to be solved is the standardization and selection of a physiologically meaningful site fo r the monitoring of body temperature. In order to select such a proper site. a brief discussion of functional anatomy and physiology of body temperatu re is here presented . together with a discussion of the advantages and disadvantages of the traditional sites, placing emphasis on a new sitenamely the tympanic membrane . The relative constancy of body temperature was recognized by O aude Bernard as a part of the regulation of the "milieu interieur" required fo r the health and proper functi oning of the cellular elements of warm-blooded anim als. The healthy man does not exist with internal body temperature much outside the normal range of 36°-38 °C , although during hard work and in febrile diseases he may tolerate fo r short periods of time temperature as high as 40°-41 °C. Denatu ration of vita l cellular proteins occur above 44 °C. Man may tolerate hypothermic states fo r short periods of time during which his body temperature is as low as 27 °-29 °C, but these temperatures are incompatible with life except under the most careful medical supervision and even then not for periods longer than a few days. The center for regulation of body temperature is in the hypothalamus ( fig. I ) . In this area two