Anesthetists Issue Temperature Guidelines

The society also recommended that forced-air warming be used to warm patients and prevent hypothermia.

The recommendations resulted from a Consensus Conference held for the purpose of issuing guidelines for preventing and/or treating inadvertent perioperative hypothermia in adults and children. Mild hypothermia, a core temperature of 36-33o C, is common during anesthesia, whether general, regional, or combined. Studies have found that inadvertent hypothermia, even if mild, induces significant cardiovascular, endocrine, metabolic, and blood composition changes, which may explain the higher mortality and morbidity rates observed in hypothermic patients.

The conferees noted that body temperature monitoring was not a standard practice in anesthesia until the mid 1960s, when the first cases of malignant hyperthermia were observed. Early diagnosis of malignant hyperthermia decreased the mortality associated with this syndrome. Monitoring patients for hypothermia could be similarly productive.

The conferees recommended that the temperature of patients under general anesthesia for more than 30 minutes and the temperature of all children under anesthesia should be monitored. Infusion fluids for children should be warmed to 38o C. Ambient temperature should be kept between 21-24o C. for adults and 21-26o C for children. After examining various forms of warming systems, including circulating water mattresses, metallic blankets, and forced-air warming, the conferees concluded that forced-air warming was the most efficient. The American Society of Anesthesiologists recommends body temperature monitoring in all patients but has issued no guidelines on actual temperatures.