THE EFFECT OF FLUID ABSORPTION ON THE DILUTION INDICATOR TECHNIQUE OF GASTRIC ANALYSIS

Abstract

In gastric analyses employing the dilution indicator technique on humans (with phenol red as the dilution indicator), many of the corrected conc. values for total acid and total chloride were greater than 165 mN and therefore hypertonic. Repetition of these analyses in dogs shows that these abnormally high values occur with considerable frequency when the test meals employed are salt free or contain salt in less than isosmotic conc. (i.e., when the test meals are hypotonic), but not when the test meals are isotonic or hypertonic. The occurrence of these abnormally high values is ascribed in small part to the analytical errors of the dilution indicator technique, but chiefly to the absorption of fluid by the gastric mucosa. Hence, hypertonic corrected conc. values do not reflect the true composition of the gastric secretion. In any expt. in which these values occur it must be presumed that fluid absorption has taken place (if this occurrence is not explainable by analytical errors), and all the corrected conc. values of that expt. must be considered spurious. To minimize errors due to fluid absorption, the dilution indicator technique should be used only with iso-tonic test-meals. All previous work by this method of gastric analysis, designed to yield vol. or conc. data concerning the various constituents of the gastric secretion, is open to question if hypotonic test meals were used and should be repeated with isotonic test meals before their conclusions can be accepted. Conclusions concerning amts. of the various components, however, are not subject to this error unless the individual components undergo absorption.