Correlation between pressure changes and solid transport in the human left colon.

A study was made to correlate colonic pressure changes and solid transport in six volunteers with a left terminal colostomy. A minimally deformable solid (sham fecaloma) 2 cm in diameter was placed in the colonic lumen together with three perfusion catheters connected to the exterior via a semi-rigid rod to record movement and pressure changes. The results obtained indicate the presence of two types of segmentary motor phenomena: those that cause displacement and those that do not. Both reflect synchronous pressure increments, although the Displacing Motor Phenomena exhibit an aborally-directed pressure gradient in contrast to the orally orientated gradient in Non-displacing Motor Phenomena (P = 0.003). The Displacing Motor Phenomena cause rapid exit of the solid from the colostomy, but with a short mean trajectory (4.2 cm). Thus, segmentary contractions may generate forward propulsion provided that aborally-directed pressure gradients occur. A slow aboral displacement also occurs during periods of motor quiescence. This may be explained by tonic contractions undetected by conventional manometry.