Compliance of the Extramural Portion of the Canine Common Bile Duct

The physiologic characteristics of the biliary tract cannot be adequately evaluated without analyzing both the resistive and compliant characteristics of the common bile duct. We studied the compliance of the common bile duct in six anesthetized dogs. Saline was infused continuously while pressure was monitored with the sphincter of Oddi intact and tied off. The mean opening pressure of the sphincter was 8.45 cm H₂O. In the obstructed duct, compliance was found to decrease with increasing pressure. The mean compliance for all five dogs at low pressures (below opening pressure) was 11.0× 10^-2μl/cm H₂O/mm², and at high pressures was 1.7 × 10^-2μl/cm H₂O/mm². Changes in flow rate did not affect the compliance of the duct. Although the compliance of the duct was found to be nonlinear overall, it was nearly linear in both the high- and low-pressure ranges.