Methods for measurement of gastric motility

Lawrence A. Szarka, Michael Camilleri
2009 American Journal of Physiology - Gastrointestinal and Liver Physiology  
Szarka LA, Camilleri M. Methods for measurement of gastric motility. There is an array of tests available to measure gastric motility. Some tests measure end points, such as gastric emptying, that result from several different functions, whereas other tests are more specific and test only a single parameter, such as contractility. This article reviews the tests most commonly available in practice and research to evaluate in vivo the gastric functions of emptying, accommodation, contractility,
more » ... d myoelectrical activity. The rationale for testing, the relative strengths and weaknesses of each test, and technical details are summarized. We also briefly indicate the applications and validations of the tests for use in experimental animal studies. contractility; emptying; accommodation; gastroparesis; dyspepsia ASSESSMENT OF THE MOTOR FUNCTIONS (motility) of the stomach is important in studies of gastric physiology and pathophysiology. Although not generally applied in gastroenterological practice, there is increasing use of tests to evaluate gastric function, particularly less invasive tests in clinical settings. There is an array of tests available to measure gastric motility. Some tests measure end points, such as gastric emptying, that result from several different functions, whereas other tests are more specific and test only a single parameter, such as contractility. This article reviews the tests most commonly available in practice and research to evaluate in vivo the gastric functions of emptying, accommodation, contractility, and myoelectrical activity. The rationale for testing, the relative strengths and weaknesses of each test, and technical details are summarized. A brief discussion is also provided for methods that have been used in animals to study motor functions of the stomach in animals. Tests to Evaluate Gastric Emptying of Solids Gastric emptying is a composite end point reflecting a variety of functions including gastric accommodation, the pressure gradient between the proximal and distal stomach, and antropyloroduodenal contractility and coordination. The trituration of solids and emptying of solid and liquid food from the stomach are arguably the most important physiological functions of the stomach. Abnormal gastric emptying, either accelerated at 1 h or delayed at 4 h, is among the factors that contribute to reporting of dyspepsia or the development of postprandial symptoms after meal challenge (35). For all tests of gastric motility and emptying, there are standard precautions (1): 1) Drugs affecting gastric motility (e.g., anticholinergics, narcotics, and prokinetics) are stopped for 48 h prior to the test, and the study is performed in the morning after an overnight fast. 2) Diabetic subjects should have a glucose level Ͻ275 mg/dl. 3) At the time the meal is ingested, Type 1 diabetic patients should receive half of their normal insulin dose. Gastric Emptying Scintigraphy Gamma camera scintigraphy is the most widely used test for the assessment of gastric motility; nuclear medicine facilities are generally available at community radiology centers. Scintigraphy is regarded as the gold standard because it provides a direct, noninvasive quantification of gastric emptying (5, 15). However, the clinical use of gastric emptying by scintigraphy has been hampered by lack of standardization with regard to meal composition, patient positioning, timing of image acquisition, and lack of appropriate normal values with some of the meals used. Additionally, scintigraphic imaging involves radiation exposure, requires costly gamma camera equipment, and is time intensive for patients and medical personnel. A simplified imaging protocol to obtain images at 1, 2, and 4 h with a standard meal was first proposed at Mayo Clinic (16), and a variation using a commercial and standardized meal was subsequently validated in a large multinational study in 123 subjects (129). The standardized meal and study protocol have been recommended for adoption across institutions by a consensus statement from the American Neurogastroenterology and Motility Society and the Society of Nuclear Medicine (1). Method. The standard meal for scintigraphic gastric emptying consists of 4 ounces of Eggbeaters or equivalent egg white substitute, 2 slices of bread (120 kcal), strawberry jam (30 g, 74 kcal), and water (120 ml) radiolabeled with 0.5-1 mCi 99m Tc sulfur colloid. The egg white, to which the 99m Tc is added, is cooked, either scrambled in a nonstick frying pan or microwaved in an appropriately shielded container. The subject ingests the whole sandwich meal and water within 10 min. Gamma camera images are acquired using a 140 keV photopeak with a 20% window (140 keV Ϯ 10%), which is optimal for detection of gamma radiation from the 99 Tc. A low-energy all-purpose collimator maximizes the count rate; a low-energy high-resolution collimator can also be used. Computerized digital images acquired in a 128 ϫ 128 word mode matrix are required for quantification.
doi:10.1152/ajpgi.90467.2008 pmid:19147807 fatcat:5m2peza2zve37fneqqmkzdwn2a