Ileus and Mechanical Bowel Obstruction

Published on 26/03/2015 by admin

Filed under Critical Care Medicine

Last modified 26/03/2015

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106 Ileus and Mechanical Bowel Obstruction

image Pathophysiology

Normal Gastrointestinal Motility

Coordinated contraction of the GI tract can be measured by evaluating its electrical and motor activity. During fasting states, the coordinated contractions are called migrating motor complexes (MMC) and are divided into three phases: resting phase, intermittent contractions of moderate amplitude, and high-pressure waves.1 When a food bolus is introduced into the intestine, the organized MMC disappear, and digested food (chyme) is propelled through the GI tract by spikes in the contraction of smooth muscle in the wall of the gut. Longitudinal progression of intestinal contents (made up by food and secretions) occurs through the coordinated response of several systems. These are:

Integration of the aforementioned processes results in coordinated muscular contractions in the wall of the stomach and intestine that move fluids in the GI tract in an aboral direction. Additionally, this activity helps to ensure that food is adequately mixed with GI secretions and digested. When motility is normal, there is adequate contact time between the absorptive surfaces of the bowel and chyme to permit absorption. Normal motility ultimately leads to the evacuation of undigested food as fecal matter.