Double-blind placebo-controlled ultrasonographic confirmation of constriction of the common bile duct by morphine.

Although the increase in the common bile duct pressure in response to morphine has been repeatedly reported in experimental animals and humans, this is the first double-blind non-invasive, ultrasonographic study designed to demonstrate constriction of the common bile duct caused by i.v. administration of morphine in surgical patients. In a double-blind, placebo-controlled, randomized study, 12 patients undergoing open cholecystectomy were enrolled. No opioids were allowed for 12 hours prior to the study. After premedication with midazolam and glycopyrrolate, anesthesia was induced by midazolam, 50 micrograms/kg-1 and thiopental, 3.0-5.0 mg/kg-1. Tracheal intubation was facilitated by succinylcholine, 1.0 mg/kg-1 and muscle relaxation was maintained with vecuronium. Anesthesia was maintained with enflurane and nitrous oxide in oxygen. After imaging the common bile duct by ultrasonography, placebo or morphine, 0.2 mg/kg-1 was injected intravenously. The diameter of the common bile duct was measured before and 4 and 8 minutes after the drug. Student t-test was utilized for statistical analysis. P < 0.05 was considered significant. No significant change in common bile duct diameter was observed after placebo administration. Morphine caused a significant reduction in the diameter of the common bile duct. Before morphine, the mean +/- SD diameter was 9.5 +/- 3.3 mm; after morphine at 4 and 8 minutes, 7.2 +/- 2.1 and 5.8 +/- 2.1 mm, respectively. It is concluded that ultrasonography in a double-blind placebo-controlled design has proven to be a valid method for the evaluation of the effect of drugs on the common bile duct.(ABSTRACT TRUNCATED AT 250 WORDS)