Defining the Relationship Between Mechanical Stress and Inadvertent Intestinal Tissue Injury In Laparoscopic Surgery

The potential to use an inappropriate amount of force when handling tissue is much higher in laparoscopic surgery than in open surgical approaches because surgeons lose the ability to directly touch and feel delicate tissue. The two most commonly injured tissues in laparoscopic surgery are the small bowel (55.8%) followed by the large bowel (38.6%) with an overall incidence of laparoscopy-induced gastrointestinal tissue injury of 0.13% but high mortality rate of 3.6%. There are currently no papers in the human literature that delineates what range of compressive stress would allow a surgeon to both operate effectively and limit the potential for tissue trauma to occur. To ameliorate this, two novel compression devices were created to produce discrete and even amounts of pressure on ex-vivo human gastrointestinal tract tissue in order to quantify the relationship between tissue stress-strain and histological measures of cellular trauma. The simple crush apparatus for tissue (SimpleCAT) consists of a weight platform and a U-shaped frame with rails. Using the SimpleCAT, significant serosal tissue deformation occurred between 350 and 450 kPa for large intestine in a pilot study of five patients. A more sophisticated compression device, the PrecisionCAT was created to investigate stress-strain and trauma in human intestinal tissue. In this study, significant tissue deformation started to occur at 300 kPa for both small and large bowel, which was also correlated to increasing pathologist trauma rating scores. Using our logistic regression analysis, the data points in the direction of establishing a maximum force threshold of 275-330 kPa on average for human intestinal tissues using a 50% threshold, however very large safety margins should be considered and used due to the high level of inter-person variation in bowel thickness and strength.Ph.D