MEASUREMENT OF THE VOLUME OF GAS IN THE GASTROINTESTINAL TRACT. VALUES IN NORMAL SUBJECTS AND AMBULATORY PATIENTS 1

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Abstract
A physical method for determination of the volume of abdominal gas based on voluntary compression of the abdomen is described. Change of abdominal pressure was measured by a gastric balloon. Change of abdominal gas volume was measured by a body plethysmograph. Abdominal gas volume was calculated by Boyle''s law: V = (B-47) dV/dP. The average volume of gas in the abdomen in 13 normal subjects was 115 ml. In 47 patients with lung disease the average was 116 ml. Accuracy of the method was tested by adding known volumes of air to the stomach or to the colon. For comparison, X-rays of the abdomen are shown before, during and after addition of volumes of gas up to 1200 ml.