An improved technic for double contrast examination of the colon by the use of compressed carbon dioxide.

Abstract

Double contrast examination of the colon has proved itself an important roentgenologic procedure for the detection of early neoplasms and for the demonstration of gross structural changes of the mucosa occurring in other types of disease. Since the original description of this technic by Fischer (1) in Germany and its development and refinement by Weber (2), Stevenson (3, 4), and others, it has remained, essentially, a method whereby air is introduced to distend the barium-coated walls of the colon. In our attempts to produce uniformly satisfactory examinations with the least inconvenience to the patient and examiner, we have resorted to the use of compressed carbon dioxide instead of air. We believe this to be a refinement of technic which possesses several advantages. Method After a preliminary barium enema study and evacuation of the barium, the patient is again observed fluoroscopically. If there has been adequate emptying of the bowel, additional routine postero-anterior and lateral films are made. Spot-films and other views are taken as indicated. It must be emphasized that satisfactory double-contrast films cannot be obtained if too much barium remains in the colon. A catheter is inserted into the rectum and carbon dioxide is allowed to flow into the bowel. The carbon dioxide is supplied by a small tank of the compressed gas (Fig. 1) , which is equipped with two gauges—one, a flow meter on a reduction valve; the other, a tank pressure gauge. The flow of gas is regulated, by turning the regulator on the reduction valve, to a rate of 1.0 to 1.5 liters per minute. When the proper rate of flow is obtained, the gas supply is shut off by turning the main valve on the tank. The regulator on the reduction valve must not be disturbed. As a precautionary measure, the rate of flow must be regulated before the catheter is inserted into the rectum. Filling of the colon with gas is observed fluoroscopically, additional films are made, and the patient is then permitted to go to the toilet. In preparing barium suspension for an enema, we have found the optimum temperature of the water to be 41 °F. In our geographical area, water at this temperature is readily obtained from the cold water faucet in winter; at other times, the water is cooled to the proper temperature. The use of cool water has two advantages: First, the colon shows a greater tolerance for the enema, possibly because the mucosa is subjected to the slight anesthetizing effect of cold. Second, all gases are more soluble in cold liquids than in warm liquids, so that the tendency for bubble formation is reduced by the lower temperature in the colon. Advantages 1. The absorption rate of gas from the colon depends largely on the partial pressure gradient between the bowel lumen and the venous blood. The average partial pressure of carbon dioxide in venous blood, with the subject at rest, is 46 mm. Hg, while the average partial pressure of nitrogen in venous blood is 573 mm. Hg (5).