Next generation of atraumatic laparoscopic instruments through analysis of the instrument-tissue interface

Mechanically induced (or iatrogenic) bowel injury from the use of laparoscopic instruments can result in devastating effects on patient outcomes both during and after surgery. The aim of this work was to investigate exactly how colonic tissue behaves both mechanically and structurally when it is subjected to a mechanical load. Analysis of force application in laparoscopic surgery is critical to understanding the nature of the instrument-tissue interaction. The development of a novel method of both histological analysis and mechanical analysis (by which the tool-tissue interaction can be characterised) has evolved through this thesis. Mechanical and histological analysis was undertaken to quantify the instrument-tissue interaction in laparoscopic surgery. This was done in both ex vivo and in vivo experiments, using an indentation method and laparoscopic instrument respectively, in porcine tissue. Mechanical stress was applied to the colon by indentation applied using the Modular Universal Surface Tester (MUST) (FalexTM Tribology USA) in ex vivo experiments to mechanically characterise the response of tissue to mechanical loading. Histological analysis was performed to examine the architecture of the tissue after loading. In vivo analysis of colon grasping was then performed to characterise grasper damage both mechanically and histologically. A mechanical measure of energy input into the tissue has been linked to consistent histological damage, above a 50 N grasping force and a loading input of 300 N.s This work has successfully identified specific loading conditions that result in tissue injury and is the first to make a link between the mechanical analyses of tissue manipulation with change to the architecture of the tissue.