The Pyloric Sphincteric Cylinder in Health and Disease

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Chapter 13 (page 51)

Intraluminal Pressure Profiles

While investigating mucosal fold movements in the distal 3.0 to 4.0 cm of the stomach, i.e. within the confines of the anatomical pyloric sphincteric cylinder, as well as in the duodenum, intraluminal pressure studies were combined with radiological imaging procedures in 11 normal subjects (Keet et al l978) (Chap. 15). These investigations may, at the same time, be utilized to determine the relationship between intraluminal pressures and radiologically demonstrable, physiological movements of the circumference of the barium column in these regions. (In this context "movements" do not imply propulsion or retropulsion of contents).

Ethical Considerations. All subjects taking part were informed, volunteer, adult, male ambulatory outpatients who had been referred for an upper gastro-intestinal radiographic study because of vague abdominal symptoms. None had had any significant clinical signs at the preliminary clinical examination. Only patients in whom no organic lesion could be demonstrated in the oesophagus, stomach and duodenum at the radiological examination were admitted to the study; it was cleared by the Ethical Committee.

Patients, Materials and Methods

Pressure recordings were obtained by means of an air-filled system and a miniature balloon, placed on the immediate oral side of the pyloric aperture (i.e. in the lumen of the pyloric sphincteric cylinder) in 5 subjects, and in the second or third parts of the duodenum in 6 other subjects.

A pressure sensitive system usually used for cardiovascular physiology, with some modifications, was employed. It consisted of a monitor (Statham SP1400) (Statham Instruments Inc., Los Angeles), a miniature transducer (Statham P37B), a recorder (Statham SP2006) and a catheter, 125 cm in length, with an outside diameter of 2.0mm. A miniature balloon 38 mm in length and 8.0 mm in diameter, covered the 6 endholes of the catheter. The volume of air introduced into the balloon to achieve zero pressure was 0.8 ml. After an overnight fast the balloon was manipulated into position under TV screening, with the subject in the erect position. Four mouthfulls of a fluid barium suspension were swallowed to delineate the lumen and for purposes of localization. In the absence of visible motor activity the diameter of the pyloric sphincteric cylinder was approximately eight times the diameter of the balloon (visible because of its air content), and the diameter of the duodenum three times that of the balloon. Artifacts such as subject movement, coughing and pressure increases produced during compression procedures were identified and excluded. Pressure increases were correlated with motility of the barium column as viewed radiographically, and vice versa.

Results in Stomach

In the pyloric sphincteric cylinder the base line of the curve represented intraluminal pressure while the cylinder was distended, in the absence of radiologically visible motor activity (Fig. 15.1). The following two distinct waves of pressure increase were noted manometrically:

  1. Irregularly occurring, nonrhythmic contractions, causing intraluminal pressure increases varying from 9.0 to 34 mm Hg (the majority being in the range of 12 to 25 mm Hg). These waves lasted for 5 to 21 seconds (the majority being in the 6 to 10 second range) (Fig. 15.1), occurred repeatedly in all subjects and conform to Type II contractions (Code and Carlson l968; Shepard l97l).

  2. In two of the subjects compound waves, consisting of a rise in base line pressure of 3.0 to 5.0mm Hg and lasting for 10 to 40 seconds, on which were superimposed waves of shorter duration (3 to 5 seconds) and higher amplitude (up to 12 mm Hg), were recorded; these conform to Type III waves (Shepard l97l).

Simultaneous radiological TV monitoring showed that both waves of pressure increase were associated with a concentric narrowing of the barium column characteristically occurring in this situation (see below). The higher the amplitude of the pressure wave, the greater the luminal narrowing appeared to be radiologically.


It was concluded that the narrowing of the barium column was due to active contraction of the walls.

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