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The use of gastric function tests by American and British gastroenterologic surgeons in different clinical situations has been studied by questionnaire. Clinical practice on both sides of the Atlantic is generally similar. The major difference in thetype of test employed is that pentagastrin cannot be used in clinical practice in the United States. Surgeons in the USA were much more liberal in their indications for gastric secretory tests than were their British counterparts. Significantly more tests were used by American surgeons, if x-ray evidence of duodenal or gastric ulcer existed, and to evaluate, a postgastrectomy patient, whether symptomatic or not. The British surgeons were much less likely to allow the results of secretory tests to influence their surgical approach. The authors discuss indications for and the clinical value of gastric secretion tests and conclude that in most instances far too many tests are being employed.

In 3 dogs with gastric fistulae, partial denervation of the acid secreting area of the stomach halved the insulin-stimulated acid secretion. Completion of a “highly selective” (proximal gastric) vagotomy resulted in a further fall of the peak acid output after insulin to 4% of control values, and there was no further change when selective and truncal vagotomy were performed. The pentagastrin dose-response curve was shifted to the right after partial denervation and remained so shifted after subsequent operations. At low doses there was a considerable decrease in acid output, and the maximal acid output was unchanged but achieved only with a higher dose of pentagastrin. These results suggest that the gastric secretory response after vagotomy is not an all-or-none phenomenon and that the fall in peak acid output after insulin is related to the extent of the acid-secreting mucosa denervated. Tailored vagotomy operations might lower the acid secretion sufficiently to heal an ulcer without interfering with other aspects of gastrointestinal function.

The intravenous infusion of insulin 0.04 U/kg-hr for 2-1/2 hours was performed in 26 patients with chronic duodenal ulcer. In 15 patients this infusion test was compared with the standard test of a single intravenous injection of insulin 0.2 U/kg. The mean lowest blood glucose level in the infusion group (25.1 mg/100 ml) was significantly higher than in the standard test (17.4 mg/100 ml), and the interval from injection to acid stimulation about twice as long (75versus 45 minutes). The peak acid output and mean rise in acidity were comparable in the two procedures. Serum gastrin responded reciprocally to insulin-induced hypoglycemia with a significant inverse correlation between blood glucose and gastrin. In 13 patients tested after vagotomy, there was no significant difference in the rise in acidities in the two groups, and the Hollander status was the same in all but one patient. The mean basal, peak, and absolute rise of serum gastrin in unoperated patients and patients with “incomplete” vagotomy were almost identical. In patients with “complete” vagotomy there was no significant rise in serum gastrin after insulin infusion. Unpleasant side effects as assessed by an independent observer were fewer and less severe in patients undergoing infusion tests than in the standard test. The insulin infusion test is recommended as a safer and more acceptable test than the standard insulin test since it avoids severe hypoglycemia and has milder side effects yet achieves comparable acidity and acid outputs. Measurements of serum gastrin after either insulin test provide no additional information helpful in the assessment of the completeness of vagotomy.

The gastric acid response to insulin was studied in a group of patients who had had incomplete truncal vagotomies and in 22 patients with complete vagotomies. A dose-response study of gastric acid secretion after insulin in 17 patients with incomplete vagotomy indicated that a dose of 0.2 unit/kg was greatly superior to 0.4 unit/kg and marginally superior to 0.1 unit/kg in eliciting the highest acid response. Eight “early” responders had a significantly greater peak acid output after insulin, 0.2 unit/kg, than 9 “late” responders, but only 1 early responder developed a recurrent ulcer compared with 4 patients in the late group. The timing of a patient's positive Hollander response to insulin was not related to the optimum dose of insulin in that patient. The blood glucose response to insulin, 0.2 unit/kg, was unchanged after complete vagotomy. The changes of blood glucose after a given dose of insulin varied from one individual to another. This variation could account for the fact that the dose which produced highest peak acid output in some individuals was 0.1 unit/kg and in others 0.2 unit/kg.