Influence of magnitude and endurance of local bile duct pressure on bile duct wall in dogs

Objective To investigate the influence of magnitude and endurance of local bile duct pressure on bile duct wall in dogs. Methods An inlaid bile duct dilator (IBDD) was designed and made by us, and the relation of pressure to fusion volume and diameter of its expanded balloon was de termined in vitro. Twenty-five mongrel dogs were randomized into 5 groups. Group A was the sham operated and IBDD was placed for biliary drainage in common bile duet. In group B and C, IBDD was placed in the common bile duct for biliary drainage to dilate it through adding 0.1ml and 0.2ml water (the pressure of expanded balloon was 0.24 kPa and 0.58 kPa, respectively) for 10 min before evacua ting the expanded balloon. In group D and E, IBDD was placed likewise except for not evacuating the balloon. The dogs in each group underwent laparotomy again 7 d after the first operation. The serum total bilirubin (TB), ALT, AST, diameter of bile duct (BD), histological changes of biliary tract wall and hepatic tissue were determined during biliary predilation and postdilation in all the 5 groups. Re sults As compared with group A, the BD of postdilation was expanded in group C (P0.05) and group D (P0.01), TB, ALT and AST in the serum were highly increased in group E (P0.01). There was no significant difference in histological changes of biliary tract wall between group A and group B. There was mucous hyperemia and hydropsy of biliary tract accompanied with partial mucous exfoliation in group C, increase of biliary tract diameter and thickening of biliary tract wall in group D and partial necrosis of hiliary tract wail and adhesion to epiploon and duodenum in group E. Conclusion There is a two-way interconversion relationship between the influence of magnitude and endurance of biliary tract pressure and bile duct wall in dogs. Normal biliary tract wall can bear the pressure to some extent and no pathological change can be caused. Suitable pressure of hiliary tract causes dilation of local bile duct and its upstream and downstream segments. On the contrary, unsuitable pressure will result in destructive changes in biliary tract.