Colonic motility: electric and manometric description of mass movement.

"Mass movement" was described at the beginning of the century by radiologists who occasionally observed how, during their explorations, barium was transported suddenly from one section of the colon to another. In the present study we wanted to center our attention on electromechanical activities accompanying large evacuations via the colostomy, as we believe that they are an expression in myoelectric and pressure terms of the "mass phenomenon" described by radiologists. To do this, we designed an electromyographic recording probe to which we attached a conventional microtransducer probe, joining them by suction. With this method we made 24-hour recordings in eight patients with sigmoid colostomy. We witnessed five large evacuations. When the electric and pressure activities that occurred a few minutes before the evacuation were analyzed, we observed that there were two clearly different phases. The first, which we call "Preliminary Phenomenon," consists of a series of contractions and spiking potentials averaging 5.6 minutes (SD 2.22); after this the "Big Contraction" appears, with mean pressure values of 127 mm Hg (SD 38.77) and mean electric values of 10.6 mV. The duration of this phenomenon averaged 24.93 seconds (SD 6.19), recorded almost simultaneously at the three recording sites studied. There is no doubt that these electro-pressure phenomena resulted in a mass transport, as we observed an intense evacuation via the colostomy in the five patients.