Relative role of pyloroplasty size, truncal vagotomy, and milk meal volume in canine gastric emptying

Abstract

The gastric emptying of 10, 20, or 40 ml/kg body mass milk meals was measured before and after Heineke-Mikulicz pyloroplasty of 3, 5, or 7 cm (6 dogs) or truncal vagotomy (3 dogs). The pyloroplasty group then underwent vagotomy, following which the tests were repeated. Initial gastric emptying (in the first 10 min) was increased after 5-and 7-cm pyloroplasties (P<0.01) and particularly after vagotomy with all sizes of pyloroplasty (P=0.001). Regardless of the volume of meal used, after vagotomy and pyloroplasty there was a 51–63% decrease in intragastric volume within the first 10 min. Increased duodenogastric reflux occurred in those dogs who showed rapid initial gastric emptying. After the first 10 min all groups were shown to have virtually normal gastric emptying, except the truncal vagotomy group in which gastric emptying was delayed (P<0.05). It is the combination of pyloroplasty with vagotomy which is required to produce the very rapid initial gastric emptying of a liquid meal following vagotomy with pyloroplasty. It is concluded that two mechanisms control the gastric emptying of a milk meal. The first acts quickly, is dependent on an intact pylorus, and is influenced by the intragastric volume; the second is a more slowly acting mechanism, requiring up to 10 min to have its effect, and is not dependent on an intact pylorus or the intragastric volume. After vagotomy and pyloroplasty, the speed of gastric emptying in the first 10 min is proportional to the original meal volume, and therefore the therapy of postvagotomy diarrhea and dumping with small frequent meals seems rational.