Abstract
Endoluminal vacuum-assisted closure (E-VAC) is a promising therapy to treat anastomotic leakages of the oesophagus and bowel which are associated with high morbidity and mortality rates. An open-pore polyurethane foam is introduced into the leakage cavity and connected to a device that applies a suction pressure to accelerate the closure of the defect. Computational analysis of this healing process can advance our understanding of the biomechanical mechanisms at play. To this aim, we use a dual-stage finite-element analysis in which (i) the structural problem addresses the cavity reduction caused by the suction and (ii) a new constitutive formulation models tissue healing via permanent deformations coupled to a stiffness increase. The numerical implementation in an in-house code is described and a qualitative example illustrates the basic characteristics of the model. The computational model successfully reproduces the generic closure of an anastomotic leakage cavity, supporting the hypothesis that suction pressure promotes healing by means of the aforementioned mechanisms. However, the current framework needs to be enriched with empirical data to help advance device designs and treatment guidelines. Nonetheless, this conceptual study confirms that computational analysis can reproduce E-VAC of anastomotic leakages and establishes the bases for better understanding the mechanobiology of anastomotic defect healing.
Highlights
Anastomotic leakages are associated with high morbidity and mortality rates in both oesophageal and colorectal anastomoses [1,2]
The aim of this study is to study the feasibility of numerically reproducing the Endoluminal vacuum-assisted closure (E-VAC) of an anastomotic leakage by means of the finite-element method (FEM)
A generic example of the E-VAC of an anastomotic cavity is presented with the purpose of exemplifying the main characteristics of the model
Summary
Anastomotic leakages are associated with high morbidity and mortality rates in both oesophageal and colorectal anastomoses [1,2]. Patients that develop leaks have a threefold death risk [2] than those who do not, with mortality reaching up to 60% in the former group [3, 4]. The prevalence of anastomotic leakages varies according to anatomical site, but values as high as 19% have been recorded in colorectal anastomoses [5]. Studies in the past years have identified the main factors associated with this detrimental post-surgical complication, contributing to improve the clinical outcome through advances in patient selection and adequate pre- and peri-operative procedures (see [5,6,7,8] and references therein). The incidence of anastomotic leaks has not decreased significantly [14], which confirms that the fundamental mechanisms at play in their formation remain unclear [15]
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