Conditions for studying the exact pressure changes in the alimentary tract

The following conditions must be observed if the actual pressure in the alimentary tract is measured and recorded with the aid of an open probe: 1. The probe must have a laterally placed opening, rather than a terminal one; 2. The opening must be as large as or larger than the internal diameter of the probe; 3. The internal diameter of the probe must be at least 1.2 mm or larger; 4. The pressure should not be measured with a nonperfusion technique if exact measurements of the intraluminal pressure are to obtained. One always has to use a perfusion, and the measured pressure depends on the speed of perfusion; 5. In order to be certain that the measured pressure corresponds to the actual pressure, one must ascertain whether the pressure will not change although the speed of perfusion is increased.