Experience with sham feeding as a test for vagotomy

Sham feeding is thought to stimulate gastric acid secretion solely via vagal pathways. We evaluated whether sham feeding can be used as a test for vagotomy. From results in 50 nonvagotomized subjects (28 unoperated duodenal ulcer patients and 22 healthy controls), a ratio of sham feeding-stimulated acid output to peak acid output of 0.10 or less was defined as abnormally low (with 95% confidence). The ratio of sham feeding to peak acid output was abnormally low in 28 of 41 (68%) vagotomized duodenal ulcer patients without clinical evidence of recurrent ulcer, suggesting that most of these patients had indeed had an effective reduction in vagal innervation of the stomach. On the other hand, 11 of 15 (73%) vagotomized duodenal ulcer patients with symptomatic, recurrent ulcers had normal ratios of sham feeding to peak acid secretion. That a normal ratio represented an incomplete vagotomy was independently suggested in 5 of these patients; in 1 an intact vagal trunk was confirmed at a second operation; in the other 4, acid secretion fell strikingly after transthoracic vagotomy, which would not have been expected to happen if vagotomy had initially been complete. In 5 vagotomized patients tested on two occasions, the ratio was reasonably reproducible. We conclude that a ratio of sham feeding-stimulated to peak acid output greater than 0.10 after an attempted vagotomy suggests persistent vagal innervation, whereas a ratio of 0.10 or less suggests, with at least 95% confidence, that vagotomy has been successful.