Low antroduodenal pressure gradients are responsible for gastric emptying of a low‐caloric liquid meal in humans

Abstract

The motor mechanisms responsible for transpyloric flow of gastric contents are still poorly understood. The aim of our study was to investigate the relationship between luminal pressures and gastric wall motion and between gastroduodenal pressure gradients and pressure waves, and ante- and retro-grade transpyloric flow. In eight healthy volunteers, intraluminal pressures were recorded from the antrum and proximal duodenum. Transpyloric flow was monitored simultaneously using duplex ultrasonography, before, during and after ingestion of 300 mL meat soup. Transpyloric emptying occurred as sequences of alternating periods of emptying-reflux-emptying. Approximately one-third of the sequences were not associated with peristalsis. The antroduodenal pressure gradients were significantly lower during nonperistaltic-related emptying than during peristaltic-related emptying (0.15 (0-0.3) kPa, and 1.7 (0.2-2.0) kPa, respectively [mean plus minus (range)], P < 0.005). The duration of emptying episodes not associated with peristalsis were significantly longer than those associated with peristalsis at (6.5 (3-8.7) s and 4.4 (2-6) s, respectively, P=0.059). Manometry detected only 56% of the antral contractions seen on ultrasound. We concluded that gastric emptying of a low-calorie liquid meal occurs both during peristaltic and nonperistaltic antral activity. In spite of lower antroduodenal pressure gradients, the emptying episodes were longer for nonperistaltic emptying, which is likely to be caused by low pyloric resistance. Considerable flow seems to occur without peristalsis during gastric emptying of a low-calorie, liquid meal in humans.

Gastric flow and mixing studied using computer simulation

“…From a mechanical perspective, the stomach is a mixer, a grinder, a storage chamber and a sophisticated pump that controls the release of aqueous, lipid and solid gastric content into the duodenum (Meyer et al 1994). Whereas many studies have concentrated on gastric motility in emptying (Schwizer et al 1992;Gilja et al 1997;Hausken et al 2002), we focus here on the role of gastric motility in the breakdown of solid particles and mixing of gastric content. We study details of gastric mixing by the coordination of specific patterns of antral contraction with temporal changes in gastric wall motion and pyloric opening, using computer simulations of the human stomach in the fed state.…”

“…The simulations can resolve pressure variations that are within the noise of manometric data, suggesting that manometry captures primarily higher pressures associated with direct luminal contact. Whereas Hausken et al (2002) report transpyloric pressure differences during emptying in the range 2-20 mmHg, Indireshkumar et al (2000) used high-resolution manometry and conditional statistics to measure mean transpyloric pressure difference of only 0.3 mmHg over 1 cm during antral quiescence and pyloric relaxation. Our computer simulations are consistent with the latter result and suggest that pressure differences of order several mmHg are likely to be a result of direct lumen-occluding contractions over the manometric sidehole.…”

Effects of posture on the physiology of gastric emptying: A magnetic resonance imaging study

“…Studies using antroduodenal manometry and concurrent duplex ultrasonography [11,12] or magnetic resonance imaging (MRI) [10] have suggested that the ''pressure-pump'' mechanism is important in the gastric emptying of fluids.…”

Inhibitory effects and mechanisms of intestinal electrical stimulation on gastric tone, antral contractions, pyloric tone, and gastric emptying in dogs

“…The critical factors that control gastric emptying are gastric tone, antral peristalsis, pyloric resistance, and duodenal feedback control. Dysfunction of any of these factors results in impairment of gastric emptying (13,19,22,24,25,27,36,38,45,47,48). Effective peristaltic antral contractions play a major role in solid gastric emptying (13,27).…”