A model of the mechanics of smooth muscle reservoirs applied to the intestinal bladder

Abstract

A model of the mechanics of smooth muscle reservoirs was derived from the stress-strain relation in smooth muscle strips. The model was applied to the intestinal bladder reservoir but may also be applied to natural reservoirs such as the bladder. The relation between reservoir volume and pressure was calculated at different values of smooth muscle tone and was found to accord with clinical results. The muscle tone of the bowel when measuring off the bowel to construct the reservoir was found to have a profound influence on its ultimate volume. Stiffening of a part of the reservoir wall as a result of edema or fibrosis will cause a substantial decrease in functional capacity, both directly as a result of a reduced expansion of the diseased part and indirectly by enhancing the stretching of the adjacent normal wall. The pressure rise produced by a slow peristaltic contraction was calculated to depend both upon the strength of contraction and on the degree of reservoir filling: Almost no pressure rise will occur in the near empty reservoir, while the highest pressure rise was calculated to occur at a volume of about 300 ml. If only a part of the reservoir contracts, more filling is needed before the pressure increases and the maximum pressure will be reached at a substantially higher volume. Localized contractions will stretch the resting reservoir wall and so activate stretch receptors, which may cause a desire to void, resulting in reduced functional capacity.

Detubularized right colonic reservoir with intussuscepted ileal nipple valve or stapled ileal (?Lundiana?) outlet

“…The present study and an earlier report [11] confirm that the first pressure wave occurs at low volume in a colonic pouch ( Table 1). The finding of an ileum-favoring difference in this parameter fits with theoretical calculations [5].…”

Kock Urinary Reservoir Maturation in Children and Adolescents: Consequences for Kidney and Upper Urinary Tract

“…The maturation of the pouch in terms of its gradual increase in capacity within 6 months along with the change to a spherical shape has been attributed to disappearance of the wall fibrosis and edema [16]. Instead, we suggest that the increase in capacity is mainly a function of the vesicoelastic properties of the bowel wall.…”

Histological Adaptation of Orthotopic Ileal Neobladder Mucosa: 4-Year Follow-Up of 30 Patients

“…By definition, detubularization provides low-pressure reservoirs as compared to tubularized types of implant [26]. However, the pressure load and the filling modalities remarkably differ in comparison with the natural condition of the terminal ileum which is not a reservoir and where the highest pressure peaks occur intermittantly during peristalsis.…”