Test Meals

The composition of the gastric juice is best determined by following lavage by a test meal. After a definite period the stomach tube is again introduced and a sample of the stomach contents is withdrawn, filtered, and examined for hydrochloric acid and pepsin. If desired, other tests may be made for rennet ferment, carbohydrates, peptones, albuminoses, lactic acid, phosphates, and fatty acids. The test for hydrochloric acid is the only one commonly applied for clinical purposes, and to aid the selection of proper diet, the others belong rather to special research.

The best test meals are Riegel and Leube's test dinner, and a modification of this, known as Ewald's test breakfast, which is easier to eat and does not obstruct the stomach tube, although it stimulates the digestive activity of the stomach somewhat less. The stomach contents should be withdrawn for examination one hour after the breakfast, but between four and five hours after the dinner.

Eiegel and Leube's test dinner consists of -

Beef soup........ .......................... 400 cubic centimetres.

Beefsteak................................... 200 " "

Whitebread................................. 50 "

Water...................................... 200 "

Ewald's test breakfast is 35 to 70 cubic centimetres of wheaten bread (one or two white coffee rolls) with 300 cubic centimetres of water or weak tea without sugar or milk. When the contents of the stomach are withdrawn one hour after ingestion of this meal its total quantity should be found reduced to 20 to 40 cubic centimetres.

In withdrawing the contents of a stomach after a test meal the same tube is used, and in the same manner as that employed for lavage, described on p. 538. It is important that its introduction should not be accompanied by violent retching, for when this takes place bile is very apt to be regurgitated into the stomach and neutralise its acid contents, rendering subsequent tests useless. The retching may be overcome by painting or spraying the pharynx with a 2- or 4-per-cent solution of cocaine, or, as Stewart recommends, by allowing the patient to swallow a few drops of the solution, to anaesthetise the oesophagus. The use of a rather stiff tube, quickly inserted, diminishes the liability to retching. The tube should not be lubricated when used for the test meals, but it may be wetted. The gastric contents may be forced out through the tube by directing the patient to forcibly expire, thereby compressing the stomach by the abdominal muscles, and simultaneously the epigastrium should be firmly compressed by the hands. It is also obtained by attaching to the stomach tube the bulb of a Davidson syringe or a suction bottle such as that in common use for aspirating the thorax or abdomen.

If no fluid flows, a little air or warm water may be forced through the tube to cleanse the obstructed fenestra.

Dujardin-Beaumetz gives a test breakfast of coffee or tea with milk and a little sugar, and one or two plain rolls; no butter. The fluid must not exceed a pint. The normal stomach digests such a meal without sensation. If within two hours there is a sensation of heat in the stomach or burning and acidity, hyperacidity is present. If there is eructation of gas, fulness and weight at the stomach, then there is diminished or hypoacidity.

If pain occurs within fifteen minutes with increasing intensity there is probably some organic lesion. In hyperacidity, moreover, Beaumetz says that the burning is worse three to four hours after eating, and is commonest in the middle of the night. It is often relieved by ingestion of food, which temporarily dilutes the acid. He urges dyspeptics to sleep on the right side, to aid the passage of food through the then dependent pylorus.

Test For Total Acidity Of The Gastric Juice

Before testing for the presence of free hydrochloric acid, the total acidity of the stomach may be obtained, which is the combined acidity produced by HC1 and lactic or other organic acids commonly developed by malfermentation. This total acidity should equal normally 40 to 65 (Ewald), which represents "the number of cubic centimetres of test solution required to exactly neutralise 100 cubic centimetres of gastric filtrate " (D. D. Stewart). The test solution is prepared as follows:

" Four grammes of NaOH dissolved in one litre of distilled water is used for neutralisation; each cubic centimetre of this solution will exactly neutralise 0.00365 gramme of absolute hydrochloric acid. The number of cubic centimetres so used multiplied by 0.00365 equals the percentage of HC1 contained in 100 cubic centimetres of the gastric filtrate " (Stewart).