Mixing studies during hepatic artery infusion in an in vitro model

A glass model of the hepatic artery network was used to study the effect of infusion rate on the degree of mixing from an end hole catheter placed in the gastroduodenal artery. Red dye solutions were infused at rates ranging from 1 ml/hour to 20 ml/minute. Effluent samples from each of 16 branch arteries were collected and dye concentrations were analyzed by means of a spectrophotometer. Low infusion rates, e.g., up to 5 ml/minute, showed streaming of the dye solutions and a nonhomogeneous dye distribution in the distal branches. At 20 ml/minute, dye distribution was much more uniform. These experiments are designed to simulate intrahepatic infusion of chemotherapeutic drug solutions. Theoretical considerations suggesting a pharmacokinetic advantage of intraarterial delivery implicitly assume uniform distribution of drug solutions to all perfused tissue. The in vitro data in this study suggests that this assumption may not be operative under certain infusion conditions. Slow infusion can lead to streaming and nonuniform distribution of infused drug solutions, which may in part explain the variability in tumor response in different tissue regions and also some observed toxicities, such as bile duct stricturing and fibrosis after intrahepatic infusions.