DEVELOPMENT OF AN INNOVATIVE EX-VIVO MODEL FOR THE EVALUATION OF STABILITY AND PRESSURE RESISTANCE OF GASTROINTESTINAL ANASTOMOSES
Kamacay Cira*1, Carina Micheler2, Saskia N. Janett1, Helmut Friess1, Andreas Obermeier3, Rainer H. Burgkart3, Philipp-Alexander Neumann1
1Department of Surgery, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany; 2Institute for Machine Tools and Industrial Management, School of Engineering and Design, Technical University of Munich, Munich, Germany; 3Department of Orthopaedics and Sports Orthopaedics, School of Medicine, Klinikum rechts der Isar, Technical University of Munich, Munich, Germany
Background: Anastomotic leakage (AL) represents a frequently occurring postoperative complication in colorectal surgery. Scientific efforts have been taken to study the gastrointestinal (GI) anastomotic stability and pressure resistance using various ex-vivo models, however, these often reveal a lack of comparability and reproducibility of scientific data. We therefore aimed to develop an ex-vivo test-setup for quantitively precise determination of the GI-anastomotic quality in terms of stability and pressure resistance with high comparability, reproducibility, and user-independence and thus to increase the understanding of the biomechanics of anastomoses and AL.
Methods: An open fluid circulation system based on a modified perfusion bioreactor, using a human machine interface, was developed to transport colored phosphate-buffered saline (PBS) at constant flow rate (low flow-model (LF) or high flow-model (HF) simulating physiological and increased intraabdominal pressure (IAP)) intraluminal into a porcine small intestinal anastomosis after passing a pressure probe. While measuring the intraluminal pressure and temperature of the surrounding PBS, different cameras record each angle of the anastomosis. Overall, 32 end-to-end anastomoses (EEA) (16 single button suture (SBS) and 16 continuous suture (CS)) on native small intestinal tissue were tested using two different flow rates (LF and HF). Maximum pressure was recorded and defined as the bursting pressure (BP).
Results: The new developed ex-vivo test-setup for determination of the GI-anastomotic stability was identified as a precise technique to evaluate stability and pressure resistance of GI-anastomoses. The application of the test setup resulted in precise and highly reproducible data that allowed reliable comparison between different techniques of GI- anastomoses (e.g., HF CS-EEA: 95% confidence interval (CI), 144.74–193.76; HF SBS-EEA: 95% CI, 136.11–191.89). Analysis of LF and HF SBS-EEA as well as LF and HF CS-EEA showed a significant difference in BP between the groups LF vs. HF. HF SBS-EEA and HF CS-EEA revealed a higher BP compared to LF SBS-EEA and LF CS-EEA (LF and HF SBS-EEA: mean difference (MD), 74.25 mmHg; 95% CI, 20.49–118.01 mmHg; p=0.010; LF and HF CS-EEA: MD, 90.125 mmHg; 95% CI, 57.17 –123.04 mmHg; p <0.001).
Conclusions: The innovative ex-vivo model for quantitively precise determination of the GI-anastomotic quality in terms of stability and pressure resistance presented a high comparability, reproducibility, and user-independence. The significant difference observed between LF and HF anastomoses support the biomechanism of time-dependent response of intestinal tissue as the stress-strain response didn't occur instantly. The application of this innovative model may pave the way for the development of new anastomotic techniques possible reducing AL, without animal testing.
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