Amanda Farah Khan, Matthew Kenneth MacDonald, Catherine Streutker, Corwyn Rowsell, James Drake, Teodor Grantcharov
Inappropriate force in laparoscopic surgery can lead to inadvertent tissue injury. It is currently unknown however at what magnitude of compressive stress trauma occurs in gastrointestinal tissues.
This study included 10 small bowel and 10 colon samples. Each was compressed with pressures ranging from 100 kPa to 600 kPa by a novel device to induce compressive “grasps” to simulate those of a laparoscopic grasper. Experimentation was performed ex-vivo, in-vitro. Grasp conditions of 0 to 600 kPa for a duration of 10 seconds were utilized. Two pathologists who were blinded to all study conditions, performed a histological analysis of the tissues. Patients were eligible if their surgery procured healthy tissue margins for experimentation (a convenience sample). 26 patient samples were procured; six samples were unusable. 10 colon and 10 small bowel samples were tested for a total of 120 experimental cases. No patients withdrew their consent. Two metrics of damage were quantified: an intestinal layer thickness calculation where the serosa layer was measured in the area of compression and compared to a local control and a histological scoring scale for tissue trauma.
Small bowel (10), M:F was 7:3, average age was 54.3 years. Colon (10), M:F was 1:1, average age was 65.2 years. All 20 patients experienced a significant difference (p<0.05) in serosal thickness post-compression at both 500 and 600 kPa for both tissue types. A logistic regression analysis with a sensitivity of 100% and a specificity of 84.6% on a test set of data predicts a safety threshold of 329-330 kPa.
A threshold was discovered that corresponded to both significant serosal thickness change and a positive histological trauma score rating. This “force limit” could be used in novel sensorized laparoscopic tools to avoid intraoperative tissue injury.