*This machine-generated transcript may have errors. If remediation or a manually-generated transcript is needed, please contact NLM Support at https://support.nlm.nih.gov.* Gastric secretion of water never stops completely even during prolonged fasting. On the other hand, the stomach continuously empties itself but nonetheless, always contains some residual value following a liquid meal, an increased amount of water is secreted into the stomach being mixed with the meal and thus contributing to postprandial gastric volume. In studies of gastric retention using the saline load test. Gastric secretion of water was neglected and postprandial gastric volume was equated with volume of meal remaining in the stomach. Today, I would like to analyze with you the respective role of the meal and of gastric water secretion in the determination of intragastric volume. And to evaluate if in fact, water secretion can be neglected. In the present studies, we have used this smaller water load 250 ml instead of 750 M L in the saline load test. And we have injected this tilt water instead of saline. This method was found to avoid Emsis which occasionally occurs with the sailing load test. Furthermore, we use the di dilution technique to repeatedly determine gastric volume during fasting and following the water load without having to completely empty the stomach. The principle of the technique is illustrated on the first slide mhm. Following a meal containing thinner red as illustrated in yellow, the stomach contains an unknown volume V. One having a concentration of thinner red C one which can be determined by sampling the unknown volume V. One can be determined by adding a known amount of red. And by using dilution principle as illustrated in red. A known volume V two of a thin red solution having a concentration C two is then injected after mixing, we have a situation which is illustrated in orange intragastric volume. V one V two has a thin red concentration C three, which can be determined by sampling stomach contents. The equation describing this situation is listed below and can be solved for V one. Since this is the only unknown term of the equation, the sum of the two sampling volumes for determining C one and C three are chosen to be equal to the volume injected V two. Thus, this double sampling and delusion technique does not modify intragastric volume by repeating this manipulation at 10 minute intervals during fasting and following a liquid meal, it is possible to repeatedly determine intragastric value. The method was used in five patients with pyloric outlet obstruction attributed to peptic ulcer disease. And we have compared the results with those obtained in 11 normal subjects. Total gastric volume is presented on the vertical axis over time on the horizontal axis during fasting and following a 250 mL water mill in normal subjects in green fasting gastric volume is 16 mL. Following the meal volume increases to only 150 mL and gradually decreases to fasting volume in 40 to 60 minutes. In our patients with pyloric outlet obstruction, as illustrated in yellow fasting volume was increased threefold to 47 M L. Following the meal volume increased to 220 M L decreased rapidly up to 20 minutes and then so slowly that it had not yet returned to fasting value after 60 minutes. What do these volumes represent immediately after a water meal? The gastric contents is mostly the water meal with only a small fraction reflecting reflecting gastric secretion. However, as time passes by and gastric secretion and emptying proceed, a gradually increasing fraction of gastric contents is secreted to in the fasting state. All gastric contents is secreted juice. Thus an increased postprandial gastric volume such as the one illustrated in yellow could result from either slow gastric empty or increased water secretion or both. During the same experiments, we have determined simultaneously gastric secretion and gastric empty using a property of pheno red that has not yet been mentioned, it is not absorbed or secreted or absorbed by the stomach. Thus, finna red can be used simultaneously as a delusion indicator to determine the gastric volume as shown in the slide and as a marker for gastric emptying. However, before presenting to you the second step of the calculation, I'll show you what people usually would like to ask me when I discuss this part of the method to avoid this, I will make any effort to simplify my description, to understand the technique. It is necessary to consider separately thinner red and water. These two components are illustrated here as two separate containers. Although in fact, they are intimately mixed in red, the mass of phe are red present in the stomach at a particular time. The value of pr can be calculated by multiplying the fre concentration of gastric contents by intragastric volume. OK. This is illustrated by W in white on the slide by comparing intragastric mass of pinna red say at time zero. And at time 10, 1 can determine the rate of emptying for pr during the time interval 0 to 10. This rate is expressed in milligrams per minute and is illustrated by G E times pr in green and red on the slide. Now to determine the rate of emptying of water in milliliter per minute. A two step calculation is required. First, we divide the rate of emptying of thin red by intragastric mass of finna red to obtain G E illustrated in green. That is the fractional emptying rate for thin or red. The slide illustrates that G E the fractional emptying rate for red is also the fractional emptying rate for water. Assuming that finna red is homogeneously uh is an homogeneous solution in water. Then, since we have previously calculated W gastric water volume in white, we cannot determine the rate of water emptying G E times W. And by difference, the rate of water secretion in white. On the other hand, the mass of red and the volume of water infused as a meal is precisely known 250 men. In the present case, it is therefore possible to split compartment W in two compartment. Number one represent the meal, it is empty during fasting and is not replenished. Once intragastric infusion is terminated. In contrast compartment, number two is gastric secretions and the portion that is emptied is constantly replaced by water secretion. We have already seen what happens to total gastric water volume. That is the sum of compartment number one and number two. In the two groups of patients, we are now going to analyze independently. Compartment number one, that is the M L of meal present in the stomach and compartment number two, that is gastric secretion. Gastric volume is illustrated on the ordinate over time. And the abs for the 11 normal subjects in green is total gastric volume already shown previously in white is the fraction of meal remaining in the stomach during fasting. By definition, gastric volume is only secreted juice following the meal. The white line corresponds to the M L of meal that has not yet been emptied. That is the meal compartment. In the previous slide, the decline of the green line. This reflects only emptying the distance between the green and the white line represents secretion compartment in the previous slide and reflects both emptying and secretion. Note that the two lines are parallel. Indicating that if any increase of water secretion of water secretion is induced by the mill, it is compensated by a simultaneous increase of emptying. After 60 minutes, gastric contents is composed only of gastric creations which reproduces the fasting situation. The next slide further illustrates this concept. The rate of water secretion in M L per minute is shown on the vertical axis. Over time. On the horizontal axis results obtained in normal subjects is shown in white following the meal. A five fold increase of water secretion is observed compared to fasting. However, this response is short lasting and has disappeared by 20 minutes. Thus, a stimulation of emptying must occur simultaneously to prevent an increase of the secretion compartment. Results obtained in patients with pyloric outlet abstraction are shown in red. Fasting secret rate is increased threefold compared to normal subjects. But the response to the meal is not increased. 20 minutes later, water secret has returned to fasting value. A significant increase of water secretion compared to normal thus exists during fasting and from 20 to 60 minutes after the meal. This difference is illustrated by the red stars. This gastric hyper secretion combined with a delayed gastric empty is responsible for the increased postprandial residual volume. This point is illustrated in the next two slides. Gastric volume is illustrated on the ordinate over time on the season. In patients with pyloric outlet abstraction. The yellow line represents the total gastric volume previously seen. The red line is the fraction of meat in the stomach and reflects only empty during the 1st 20 minutes. The two lines are reasonably parallel but they subsequently diverge the yellow line plateauing while the red line continues downwards at 60 minutes. The distance between the two lines which illustrates the secretion compartment is larger than at 30 minutes or during fasting, it then represents 60% of the gastric quote residual unquote. Thus, two factors that markedly increase gastric volume postprandially are one slower emptying and two increased gastric secretion shown in the previous slide. The alteration of gastric emptying in patients with pyloric outlet abstraction are illustrated in the next slide independently from water secretion. The fraction of the meal remaining in the stomach is shown on the vertical axis over time on the horizontal axis. For normal subjects in white and for patients with outlet obstruction in red. The slope of decline of these quote mili of meal unquote represents only emptying without interference of secretion. It appears clearly that empty is abnormally delayed in patients with pyro outlet obstruction. But that the difference is much less impressive than when total volume is considered. Could I have the light piece slide down? In conclusion, evaluation of gastric retention using a water or saline load test is and remains a good clinical method. However, the results should be interpreted cautiously in the presence of gastric hypersecretion. For example, in py outlet obstruction produced by peptic or disease. Large postal gastric volume may be found with only minor delay of gastric empty. Thank you.