Mechanism of Staple Line Leak After Sleeve Gastrectomy via Isobaric Pressurisation Concentrating Stress Forces at the Proximal Staple Line

PURPOSE: Staple line leak following sleeve gastrectomy is a significant problem and has been hypothesised to be related to hyperpressurisation in the proximal stomach. There is, however, little objective evidence demonstrating how these forces could be transmitted to the luminal wall. We aimed to define conditions in the proximal stomach and simulate the transmission of stress forces in the post-operative stomach using a finite element analysis (FEA). MATERIALS AND METHODS: The manometry of fourteen patients post sleeve gastrectomy was compared to ten controls. Manometry, boundary conditions, and volumetric CT were integrated to develop six models. These models delineated luminal wall stress in the proximal stomach. Key features were then varied to establish the influence of each factor. RESULTS: The sleeve gastrectomy cohort had a significantly higher peak intragastric isobaric pressures 31.58 ± 2.1 vs. 13.49 ± 1.3 mmHg (p = 0.0002). Regions of stress were clustered at the staple line near the GOJ, and peak stress was observed there in 67% of models. A uniform greater curvature did not fail or concentrate stress under maximal pressurisation. Geometric variation demonstrated that a larger triangulated apex increased stress by 17% (255 kPa versus 218 kPa), with a 37% increase at the GOJ (203kPA versus 148kPA). A wider incisura reduced stress at the GOJ by 9.9% (128 kPa versus 142 kPa). CONCLUSION: High pressure events can occur in the proximal stomach after sleeve gastrectomy. Simulations suggest that these events preferentially concentrate stress forces near the GOJ. This study simulates how high-pressure events could translate stress to the luminal wall and precipitate leak. GRAPHICAL ABSTRACT: [Image: see text]