Tests of Gastric Neuromuscular Function

Schematic of a stomach with regional gastric physiology/function. Gastric emptying reflects the coordinated function of the fundus, corpus, antrum, pylorus, and duodenum. Important events for gastric emptying include fundic relaxation and accommodation, antral contractions for trituration, pyloric opening, and overall fundic-antral-pyloric-duodenal coordination. Adapted with permission from Lacy et al.¹⁵⁴

Gastric emptying scintigraphy. After ingestion of a radioactive egg sandwich meal, images are obtained immediately after eating (T = 0) and at 1, 2, 3, and 4 hours postprandially (upper panel). The percent remaining in the stomach is depicted over time (lower panel).

Regional gastric emptying with delayed distal gastric emptying in functional dyspepsia. The figure demonstrates selective retention in the distal stomach, notably seen at 240 minutes after meal ingestion.

Capsule assessment of gastric emptying using a pH/pressure-sensing capsule. After capsule ingestion at time 0, the pH tracing (red line) decreases to a pH of about 1.4. This is followed by an increase in pH representing the buffering of the gastric acid by a meal, followed by a decline of the gastric pH to about 1. At 2¾ hours after capsule ingestion, there is an abrupt increase in pH from 1 to 6 representing the expulsion of the capsule from the acidic stomach to the alkaline duodenum. This gastric emptying of the capsule is preceded by high-amplitude contractions (blue line).

¹³C-Octanoate breath test for gastric emptying. Sequential breath samples every 15 minutes are obtained after ingestion of a ¹³C-octanoate containing meal. These are analyzed for the fractional excretion of ¹³C and can be expressed as the fraction remaining or the percent dose per hour (A). B illustrates the good correlation between breath testing and scintigraphy in assessing gastric emptying when tests are performed simultaneously. Reprinted with permission from Chey et al.¹⁵⁵

EGG. A shows the regular 3-cycle/min pattern with an increase in amplitude postprandially. B shows examples of bradygastria and tachygastria.