Influence of epidural analgesia upon postoperative fatigue.

This study examined the effect of epidural analgesia on the development of postoperative fatigue and the ability to ambulate after surgery. Seventeen patients admitted for elective abdominal surgery were randomized to receive postoperative analgesia with a continuous infusion of epidural fentanyl (epidural group) or intermittent intramuscular morphine (non-epidural group). Fatigue was assessed on an analogue scale of 1 (fit) to 10 (fatigued). Steady state measurements of respiratory gas exchange, respiratory rate, tidal volume and heart rate were made before operation and repeated on the third postoperative day. Energy expenditure was calculated from Weir's formula. Ambulatory measurements were made during treadmill walking at a work rate of 20 kpm min-1 (3.3 W). At rest, patients in both groups had a similar cardiorespiratory response to surgery irrespective of the method of analgesia. Subjective feelings of fatigue were significantly greater in those patients who had received epidural analgesia (P less than 0.01) and patients in this group expended significantly more energy in performing the postoperative exercise test than did those in the non-epidural group (P less than 0.05). The use of epidural opiate analgesia does not limit postoperative fatigue in patients undergoing upper abdominal surgery.