Combination of thoracic epidural anesthesia does not always induce hypothermia during general anesthesia

Abstract

The combination of general anesthesia and epidural anesthesia has been considered to worsen the degree of hypothermia. However, epidural anesthesia reduces cardiac output, which may prevent redistribution hypothermia. Twenty-four patients undergoing gynecologic surgery were randomly assigned to one of two groups: recipients of epidural injection of 1% ropivacaine and general anesthesia (epidural and general group, n=12) and recipients of epidural injection of saline and general anesthesia (general group, n=12). Fifteen minutes after epidural injection of 12 mL of 1% ropivacaine (epidural and general group) or saline (general group), general anesthesia was induced with propofol, and tracheal intubation was facilitated with vecuronium. Anesthesia was maintained with 35% oxygen and 0.4% to 2% isoflurane with a nitrous oxide mixture. Tympanic (core), forearm, and fingertip temperatures were recorded before the epidural injection, just before induction of general anesthesia, just after tracheal intubation, and every 15 minutes up to 90 minutes after tracheal intubation. The core temperature was significantly higher in the epidural and general group than in the general group from 30 to 90 minutes after tracheal intubation. Epidural anesthesia with 1% ropivacaine may prevent redistribution hypothermia during general anesthesia for gynecologic surgery.