Hyperthermia related to epidural analgesia during labor

Although hypothermia has been reported during epidural anesthesia performed for nonobstetrical surgery or cesarean section, epidural analgesia for labor may lead to hyperthermia. Its incidence, time-course and intensity are influenced by multiple factors including site of measurement, duration of labor preceding epidural analgesia and perhaps ambient temperature and occurrence of shivering. During the first 2-5 h of epidural analgesia, a significant increase in temperature is not usually observed. Then, if labor is prolonged (mostly in primiparas), temperature may increase at a rate of 0.07-0.15 degrees C per hour. Imbalance between reduced heat loss during epidural analgesia and labor-induced heat production has been implicated but impairment of central temperature regulation cannot be excluded. This hyperthermia is usually of mild intensity (< 38 degrees C) and occurs in the absence of any infectious process; maternal and fetal consequences are also usually absent and treatment is probably unnecessary. However, fetal tachycardia may occur and the potential for a deleterious effect on the fetus remains controversial. Various measures for cooling the mother have been proposed but their efficacy has not been evaluated. The recognition that epidural analgesia may provoke hyperthermia may help to avoid inappropriate use of antibiotics or fetal extraction.