Hyperthermia during Epidural Analgesia

Hyperthermia frequently complicates epidural analgesia in patients undergoing labor and delivery^{[202] [203] [204] [205]} and in nonpregnant postoperative patients.^[206] A clinical consequence of this hyperthermia is that women given epidural analgesia are more often administered antibiotics than those treated conventionally, and their offspring are more commonly treated for sepsis.^{[203] [207] [208]}

Because passive hyperthermia and excessive heat production are unlikely etiologies, elevated body temperature in laboring and postoperative patients is presumably true fever resulting from infection, tissue damage atelectasis, and other causes. This theory is consistent with reports demonstrating a correlation between hyperthermia during epidural analgesia and clinical signs of infection.^[209] Some evidence also indicates that hyperthermia during epidural analgesia is highly associated with placental inflammation.^[210] These authors concluded that "Epidural analgesia is associated with intrapartum fever, but only in the presence of placental inflammation. This suggests that the fever reported with epidural analgesia is due to infection rather than the analgesia itself."

The conventional assumption is that hyperthermia is caused by the technique, although no convincing mechanism has been proposed. However, it is worth remembering that pain in "control" patients is usually treated with opioids—which themselves attenuate fever. Fever associated with infection or tissue injury might then be suppressed by the low doses of opioids usually given to "control" patients while being expressed normally in patients given epidural analgesia. The extent to which this mechanism contributes remains to be determined, but no convincing alternative explanation has been advanced.