Colonic transit time and pressure based on Bernoulli’s principle

Abstract

PurposeVariations in the caliber of human large intestinal tract causes changes in pressure and the velocity of its contents, depending on flow volume, gravity, and density, which are all variables of Bernoulli’s principle. Therefore, it was hypothesized that constipation and diarrhea can occur due to changes in the colonic transit time (CTT), according to Bernoulli’s principle. In addition, it was hypothesized that high amplitude peristaltic contractions (HAPC), which are considered to be involved in defecation in healthy subjects, occur because of cecum pressure based on Bernoulli’s principle.MethodsA virtual healthy model (VHM), a virtual constipation model and a virtual diarrhea model were set up. For each model, the CTT was decided according to the length of each part of the colon, and then calculating the velocity due to the cecum inflow volume. In the VHM, the pressure change was calculated, then its consistency with HAPC was verified.ResultsThe CTT changed according to the difference between the cecum inflow volume and the caliber of the intestinal tract, and was inversely proportional to the cecum inflow volume. Compared with VHM, the CTT was prolonged in the virtual constipation model, and shortened in the virtual diarrhea model. The calculated pressure of the VHM and the gradient of the interlocked graph were similar to that of HAPC.ConclusionThe CTT and HAPC can be explained by Bernoulli’s principle, and constipation and diarrhea may be fundamentally influenced by flow dynamics.

Evaluation of the Appropriate LigaSure™ Device to Transect the Appendix—A Comparison between 5 mm and 10 mm Laparoscopic Devices in an Ex Vivo Trial

“…Therefore, the use of a 10 mm instrument on the umbilical site does not negatively impact cosmetic outcomes. Furthermore, according to recent studies on the mechanism of bowel movement and its pathologies, it was shown that the normal pressure in the cecum is 60–80 mmHg, which decreases to 20–40 mmHg in the central part of the large bowel and then increases to 60–100 mmHg in the proximity of the rectum [ 44 , 45 , 46 , 47 , 48 ]. This finding supports our theory that a maximum burst resistance of 60.5 mmHg achieved with a 5 mm instrument is insufficient.…”