Relationships between spatial patterns of colonic pressure and individual movements of content

The aim of this study was to examine the relationship between colonic pressure waves and movement of content. In 11 healthy subjects, pressures were recorded at 10-cm intervals from cecum to rectum for 32 h. In six subjects, transit was simultaneously measured for 8 h after direct cecal instillation of 1.5 mCi of Tc-99m sulfur colloid. Thirty-two percent of isotope movements were related to nonpropagating activity and twenty-eight percent to propagating sequences. The extent of isotope movement related to propagating sequences (25.1 +/- 2.1 cm) was greater than that due to nonpropagating activity (12.8 +/- 0.7 cm; P = 0.0001). Propagating sequences originated significantly more frequently (P = 0.004) and propagated further (P = 0.0006) in the proximal compared with the distal colon. Only 36% of propagating sequences were propulsive of content, and compared with nonpropulsive sequences, these propagated further (41 +/- 6 vs. 27 +/- 2 cm; P < 0.05) and had a higher probability of originating proximally (P = 0.0003), a higher pressure wave amplitude (50 +/- 5 vs. 34 +/- 4 mmHg; P = 0.0001), and slower velocity (2.2 +/- 0.3 vs. 3.6 +/- 0.47 cm/s; P = 0.02). We conclude that most movements of colonic content are related to pressure waves. There is marked regional variation in the prevalence, velocity, and extent of propagation of propagating pressure wave sequences, which are an important mechanism for transporting content over long distances. The effectiveness of transport by a propagating sequence is influenced by its site of origin, amplitude, and velocity.