A comparison of low-dose epidural morphine-bupivacaine infusion with low-dose morphine infusion

Abstract

This study has been carried out on ASA I and II patients who were all having major abdominal surgery. The first group included the patients having general anaesthesia together with epidural morphine infusion; the second group included the patients having general anaesthesia together with epidural morphine and bupivacaine infusion and the third group being the control group was composed of the patients having general anaesthesia alone. The epidural infusion started with the operation and lasted for 12 hours. The catheter was withdrawn at 24 h. Pre-operative and post-operative measurements of arterial blood gases, blood pressure, blood glucose and cortisol levels were all made. Morphine-related minor respiratory depression, in groups I and II lead to a significant decrease in pH and postoperative increase in CO2 level. The increase in blood glucose and cortisol levels was significantly lower in group II, but in the control group this increase was significant. Sensation was completely lost for 24 h in those patients having a morphine and bupivacaine infusion whereas in most of the patients having a morphine infusion alone, sensation returned after 8 h. In the post-operative period, the pain felt during sitting and coughing was measured using the Visual Analog Scale. Although scores in group I and II were found to be lower compared with the control group, this reduction was most significant in group II. Motor block did not develop in either of the groups having the epidural infusion. As a result, it was concluded that low-dose epidural morphine and bupivacaine infusion combined with general anaesthesia leads to a more comfortable postoperative period with a significant decrease in the neuroendocrine response to stress when compared to general anaesthesia alone.