A new method for estimating intestinal capillary pressure.

The purpose of this study was to compare the venous occlusion method for measuring capillary pressure with the stop-flow isovolumetric method in the cat small intestine. Venous occlusion pressures were determined from the inflection point of the venous pressure tracing after sudden occlusion of the venous outflow cannula. Venous occlusion pressure was highly correlated (r = 0.98, P less than 0.01) with stop-flow capillary pressure. This finding indicates that the major sites of fluid filtration and vascular capacitance reside at the same segment of the intestinal microcirculation. The venous occlusion method is a relatively simple technique for measuring whole-organ capillary pressure that is not constrained by the technical difficulties associated with volumetric/gravimetric techniques.