METHODS FOR THE ASSESSMENT OF GASTRIC-EMPTYING IN HUMANS - AN OVERVIEW

A number of different methods are used for the measurement of gastric emptying in humans, and all have some advantages and disadvantages. Th e method of choice will depend on whether solid or liquid meals are to be studied, the level of precision required, the degree of invasivene ss that the subject or patient will tolerate, ethical considerations, and the facilities available. It is easier to measure the emptying of liquid meals, but the emptying of solid meals is the true reflection o f what happens during normal life, and is therefore of more clinical i mportance. Scintigraphy, with appropriate labelling of the test meal c omponents and appropriate corrections applied to the images obtained, is the method of choice for clinical investigation of disturbed emptyi ng patterns and can be applied to solid or liquid meals, but its appli cation is limited by the need to restrict exposure to ionizing radiati on. The double sampling gastric aspiration technique allows serial mea surements of the composition of the gastric contents and of the volume and composition of gastric secretions but can be used only with liqui d meals. Other imaging techniques (ultrasound, MRI) and epigastric imp edance measurements produce results that correlate well with those obt ained by scintigraphy or aspiration. MRI has the unique feature of all owing the physician to follow gastric emptying while at the same time being able to observe any morphological abnormalities which may contri bute to abnormal gastric function. Tracer methods, such as following t he appearance in blood of paracetamol, may be useful for screening pur poses in large populations. Regardless of the method used, the investi gator must be aware of the large interindividual variability which exi sts in the rate of gastric emptying in normal healthy individuals and of the factors known to influence the gastric pattern.