Pressure characteristics of the human ileocecal region--a key to its function.

Manometric recordings of the ileocecal region were made in 7 patients with a diverting loop ileostomy. An increase in the mean amplitude of phasic waves (10 +/- 3.2 cmH2O, p less than 0.01) associated with a smaller elevation of baseline pressure (6.4 +/- 1.2 cmH2O, p less than 0.01) was observed at the ileocecal junction in 81.5% of pull-throughs. Phasic activity was present at 63% of stations in the terminal ileum, but a discrete zone of persistent tonic activity was not observed. After colonic distention there was an increase in the amplitude (10 +/- 3.4 cmH2O, p less than 0.05) and duration of phasic activity (38% +/- 7%, p less than 0.01) in the junctional zone, as well as an increase in baseline pressure (4.8 +/- 1.3 cmH2O, p less than 0.05). Ileal distention produced a fall in junctional pressure. This study shows that the motility of the terminal ileum is characterized by a high incidence of phasic activity, which may be modulated by intraluminal distention. The findings suggest that flow across the ileocecal junction is regulated by modulation of phasic activity in the terminal ileum and not by a discrete zone of persistent tonic activity.