MECHANICS OF PULSATILE TRANSPYLORIC FLOW IN THE PIG

1. In eight conscious pigs equipped with gastric and duodenal cannulae , the relationship of transpyloric flow to gastro-duodenal motor event s was evaluated during gastric emptying of 1000 mi of saline. Rates of liquid gastric emptying were correlated with pressures at the antrum, pylorus and duodenum, recorded by a sleeve sensor and multiple perfus ed side-holes. Transpyloric flow was recorded concurrently by continuo us collection and weighing of the duodenal effluent. 2. In three pigs the above measurements were repeated during concurrent videofluoroscop y of gastric emptying after adding 100 mi of liquid barium to the gast ric instillate. 3. The mean volume of saline emptied in 30 min was 627 +/- 51.2 ml. Pulsatile flow accounted for 71% of total emptying. Puls es had a mean flow rate of 3.9 +/- 0.44 ml s(-1). Most flow pulses (59 %) occurred during the first 5 min of emptying. 4. Distinctive, low-am plitude (4.8 +/- 0.33 mmHg), relatively long-lasting (15.8 +/- 0.46 s) antral pressure waves were associated with 58% of flow pulses. In all antral pressure recording points, the first and longest duration comp onent of these pressure waves had an identical timing, amplitude and w aveform consistent with pressurization of the entire antrum-gastric ca vity. 5. Videofluoroscopy and concurrent manometry showed that these a ntral common cavity pressure waves were associated with non-lumen-occl usive contractions of the gastric wall, initially observed at the corp us which propagated down to the pylorus; 93% of these contractions bec ame lumen occlusive in the terminal antrum and pylorus when pressure w aves of a unique pattern for each recording point were recorded at thi s level. 6. The onset of 68% of the flow pulses which accounted for 62 % of pulsatile emptying occurred in the interval (mean 7.9 +/- 0.65 s) between the onset of the common cavity wave and the onset of localize d, lumen-occlusive distal antral-pyloric pressure waves. 7. These find ings indicate that in the pig, pulsatile emptying of non-nutrient liqu ids into the duodenum occurs predominantly during the non-lumen-occlus ive stage of a propagated gastric contraction, which is recognisable a s a common cavity pressure wave. This is a previously inadequately rec ognized pattern of gastric pumping.