Estimation of Ascites Volume in Post-hepatectomy Patients Using Flow in Porous Media Model

Abstract

Ascitic fluid formation is one of the most common complications in post-hepatectomy patients. The fluid is partially formed by hydrostatic pressure difference between liver and intra-abdominal cavity causing the leakage across Glisson's capsule. Moreover, the oncotic pressure difference can cause fluid shift between two spaces especially in in post-hepatectomy patients. Since the liver tissue is resected, the amount of albumin production from hepatocytes decreases, resulting in the reduction of the oncotic pressure within liver sinusoids. Insight of the ascites formation mechanism can lead to proper post-operative management which can reduce severity of the complication. In this study we present a mathematical model to predict the amount of ascites formation in several extents of hepatectomy. The fluid circulations within liver lobules are described as flow in porous media using Darcy's law. The roles of hydrostatic and oncotic pressures on ascites production were investigated by comparing amounts of the leaked fluid between the models with and without the effect of albumin. The ascites formation from the hydrostatic pressure after hepatic resection is decreased slightly due to smaller surface area of Glisson's capsule. In contrast, the fluid volume is escalated massively by the reduction of liver oncotic pressure. However, the results show that the major hepatic resections (≥ 3 lobes) does not always cause larger amount of the ascites compared to the minor resections (< 3 lobes). The operation involving posterior part of the liver (segment IV, VII, and VIII) tends to have higher risk of ascites collection. The administration of albumin or drugs such as diuretics in patients with post-operative serum albumin ≤ 3 g/dL may reduce the incidence of ascites.