Effect of epidural morphine on post-operative pulmonary dysfunction

Abstract

The effect of post-operative epidural morphine analgesia on pulmonary function was assessed after abdominal surgery and compared to conventional analgesia. In a control group, ten patients received a parenteral analgesic, non-narcotic drug. In a second group of 11 patients, epidural morphine was injected after the operation and continuous analgesia was prolonged until the 3rd post-operative day by means of repeated injections through an epidural catheter. Analgesia was tested on a visual pain scale. Pulmonary function was evaluated by measurements of blood gases, pulmonary volumes (vital capacity, by spirometry, and functional residual capacity by helium dilution technique) and forced expiratory volume in one second. Measurements were performed on the day before the operation and on the first, third and sixth post-operative days. Pain scoring documented a better analgesia in the epidural group during the post-operative period. By contrast, epidural morphine was unable significantly to improve VC, FEV1 and FRC during the post-operative course. The results suggest that pain is not an important factor of decreased post-operative pulmonary function.