Post-cholecystectomy pulmonary function following interpleural bupivacaine and intramuscular pethidine

Twenty-four patients who were to undergo cholecystectomy were randomised into two groups, one to receive postoperative analgesia with interpleural bupivacaine, 20 ml of a 0.5% solution with adrenaline 5 micrograms/ml, and the other to receive intramuscular pethidine, 1 mg/kg. Preoperative and postoperative pulmonary function, postoperative pain scores, and days from operation to hospital discharge were recorded and statistically compared. There was no significant difference in pain scores, nor in days to discharge; however, postoperative pulmonary mechanics were significantly poorer in the interpleural group. A hypothesis to explain the differences is offered.