Delayed postoperative gastric emptying following intrathecal morphine and intrathecal bupivacaine

Purpose: A decrease in the rate of gastric emptying can delay resumption of enteral feeding, alter bioavailability of orally administered drugs, and r esult in larger residual gastric volumes, increasing the risk of nausea and vomiting. We compared the effects of 1) intrathecal bupivacaine (17.5 mg) and 2) the combination of intrathecal morphine (0.6 mg) and intrathecal bup ivacaine (17.5 mg) on the rate of gastric emptying in patients undergoing e lective hip arthroplasty. Methods: Twenty four fasting ASA 1-3 patients wer e randomly assigned, in a double blind manner, to receive intrathecal hyper baric bupivacaine (17.5 mg) either alone (group 1), or followed by intrathe cal morphine (0.6 mg) (group 2). Gastric emptying was measured (using an ac etaminophen absorption technique), twice in each patient preoperatively, an d approximately one hour postoperatively. Gastric emptying parameters are: AUC (area under the plasma acetaminophen concentration time curve), maximum plasma acetaminophen concentration (Cmax), and time to Cmax (tCmax), analy zed using paired Student's t tests. Results: Gastric emptying rates were re duced in both group 1 (AUC = 14.98(3.8) and 11.05(4.6) pre-and postoperativ ely, respectively) and group 2 (AUC = 13.93(3.59) and 6.4 (3.42) pre- and p ostoperatively, respectively); the magnitude of the reduction was greater i n group 2 {AUC (P = 0.04), Cmax (P = 0.05), tCmax (P = 0.13)}. Conclusion: The combination of intrathecal morphine (0.6 mg) and intrathecal bupivacain e (17.5 mg) delays gastric emptying postoperatively.