Further studies on the perfusion method for measuring intestinal absorption in man: the effects of a proximal occlusive balloon and a mixing segment.

The reliability and accuracy of the two-lumen tube perfusion method for measuring intestinal absorption in man has been assessed by the use of a proximal occlusive balloon in nine normal volunteers. Luminal occlusion significantly reduced the variability of individual glucose and water absorption rates, and reduced the variability of triplicate marker concentrations within individual studies. Mean absorption rates of glucose, water, sodium, and chloride were not significantly affected by luminal occlusion. Absorption rates obtained with the triple-lumen tube method were rather more variable both within and between individuals, but a statistical comparison of the accuracy of the two methods could not be made. These results are discussed in relation to the contribution of endogenous gut secretion and proximal reflux of infused fluid to the variability of absorption rates obtained by the perfusion technique.