RESPONSE OF THE HUMAN INTESTINE TO HIGH-VOLUME INFUSION

The motor patterns and luminal capacity of the human intestine should affect symptoms and resorption during pathological, massive small intestinal flow. Little is known of human intestinal motility in this situation. This study aimed at mimicking secretory diarrhoea (experimentally) in healthy volunteers by intrajejunal infusion of a non-absorbable iso-osmotic solution at 20 ml/min. During the infusion intraluminal jejunal pressures and small intestinal transit times were measured. The infusion initially caused jejunal contractile activity similar to that of the fed state but this was replaced by discrete clusters of contractions (DCCs) after 29.1 ((SEM) 8.2) minutes. DCCs each lasted 38 ((SEM) 0.8 seconds) and were associated with colicky abdominal discomfort. Later, after 1400-1800 ml had been infused, distal jejunal pressure waves fell to 10 mm Hg or less. Frequent fasting DCCs predicted earlier onset and more frequent DCCs during the infusion. Thus, the rate and volume of flow during simulated secretory diarrhoea determine the pattern of the small bowel pressure profile; eventually, a volume load is reached in which the small bowel acts as a poorly segmenting conduit resulting in very fast transit rates.