Pediatric functional dyspepsia

　　1. Etiology

　　The etiology of functional dyspepsia is unknown, and it is currently considered to be the result of the combined effect of multiple factors. These factors include diet and environment, gastric acid secretion, Helicobacter pylori infection, abnormal gastrointestinal motility, psychological factors, and some other gastrointestinal functional disorders, such as gastroesophageal reflux disease (GERD), aerophagia, irritable bowel syndrome, and so on.

　　2. Pathogenesis

　　The pathogenesis is not yet clear, and is related to the following mechanisms:

　　1. Diet and Environmental Factors

　　The symptoms of patients with functional dyspepsia are often related to diet, and many patients often complain that carbonated drinks, coffee, lemon, or other fruits, as well as fried foods, can worsen dyspepsia. Although the double-blind food challenge test has questioned the significance of food triggers, many children still feel that their symptoms have been reduced after avoiding the above foods and balancing their diet.

　　2. Gastric Acid

　　Some patients with functional dyspepsia may have ulcer-like symptoms, such as hunger pain, which gradually relieves after eating, and there is a pinpoint tenderness in the abdomen. When acid-suppressing agents or acid-inhibiting drugs are given, the symptoms can be relieved in the short term. All these suggest that the onset of these patients is related to gastric acid.

　　However, the vast majority of studies have confirmed that patients with functional dyspepsia do not have an increase in baseline or maximum gastric acid secretion, and there is no correlation between gastric acid secretion and ulcer-like symptoms, nor is there a correlation between the severity of symptoms and maximum gastric acid secretion. Therefore, the role of gastric acid in the pathogenesis of functional dyspepsia still needs further study.

　　3. Chronic Gastritis and Duodenitis

　　About 30% to 50% of patients with functional dyspepsia are confirmed to have antral gastritis by histological examination. Many European countries consider chronic gastritis to be a functional dyspepsia, believing that chronic gastritis may affect the motility of the stomach through nervous and humoral factors. Some authors also believe that non-ulcerative duodenitis also belongs to functional dyspepsia. It should be pointed out that the severity of the symptoms of functional dyspepsia is not parallel to the inflammatory changes of the gastric mucosa.

　　4. Helicobacter pylori Infection

　　Hp is a Gram-negative bacterium that usually colonizes the surface of the mucus layer of the stomach. The infection rate of Hp in asymptomatic adults is more than 35%, and more than 90% of patients with duodenal ulcers have Hp. Bismuth agents combined with antibiotics can eradicate Hp, causing histological gastritis to regress, and can also reduce the recurrence rate of ulcers from more than 80% per year to less than 10% per year. Therefore, Hp is an important cause of duodenal bulb ulcers and chronic antral gastritis, which is basically clear.

　　Functional dyspepsia in children often leads to emaciation and malnutrition, resulting in decreased body resistance and an increased risk of infectious diseases. Chronic functional dyspepsia can lead to malnutrition in children, which in turn affects their growth and development.

　　1. Motor disorder-like dyspepsia

　　The main manifestations of this type of patient are bloating, early satiety, and belching. Symptoms often worsen after eating. Abdominal pain, nausea, and even vomiting may occur when overfull. Dynamic examination shows that about 50% to 60% of patients have contraction and relaxation disorders of the proximal and distal stomach.

　　2. Reflux-like dyspepsia

　　The prominent manifestation is retrosternal pain, heartburn, and regurgitation. Endoscopic examination does not show esophagitis, but 24-hour pH monitoring can show that some patients have gastroesophageal acid reflux. For patients without acid reflux who have these symptoms, it is considered to be related to increased acid sensitivity of the esophagus.

　　3. Ulcer-like dyspepsia

　　The main manifestations are similar to those of duodenal ulcer, with pain at night, hunger pain, which can be relieved by eating or taking antacid drugs. Some patients may have acid regurgitation, and a few patients may have heartburn. The symptoms are chronic and cyclic, and endoscopic examination does not show ulcers or erosive inflammation.

　　4. Non-specific dyspepsia

　　Dyspepsia that cannot be classified into the above types often occurs with irritable bowel syndrome.

　　However, except for reflux-like dyspepsia, the other classifications have no significant clinical significance. Many patients do not belong to only one subtype, and this classification is unrelated to pathophysiological disorders and clinical efficacy. For example, patients with dyspepsia in the motility disorder subtype have no higher incidence of gastric dysmotility than other subtypes, and the efficacy of prokinetic drugs is not necessarily better than that of other subtypes. However, the incidence of gastroesophageal reflux in patients with reflux subtypes of dyspepsia is indeed higher than that in other subtypes, and the efficacy of anti-reflux treatment is better.

　　Not all children with functional dyspepsia need to receive medication. Some children, after being diagnosed by doctors and finding that they are healthy and the test results are normal, can prevent the disease by changing their lifestyle and adjusting their diet. This includes establishing good habits, avoiding psychological stress factors and spicy foods, avoiding the use of non-steroidal anti-inflammatory drugs, and for those who cannot stop taking medication, simultaneous use of gastric mucosal protective agents or H2 receptor antagonists should be considered.

　　1. Routine blood tests, liver and kidney function tests, blood glucose, thyroid function tests, fecal occult blood test, and 24-hour pH monitoring of the esophagus and stomach should be performed. Routine examinations often do not show any abnormalities, and some may have mild anemia. Diabetes, connective tissue disease, thyroid dysfunction, and diseases of the liver, kidneys, and pancreas should be excluded.

　　2. Upper gastrointestinal endoscopy, liver and gallbladder ultrasound, chest X-ray examination, ultrasound or radioactive isotope gastric emptying examination, gastrointestinal pressure measurement, and a variety of gastrointestinal motility examination methods such as gastrointestinal motility should be performed. These methods play a very important role in the diagnosis and differential diagnosis of FD.

　　2. Upper gastrointestinal endoscopy should be performed to exclude esophageal, gastric, duodenal inflammation, ulcers, erosion, tumors, and other organic lesions. Ultrasound examination should exclude liver, gallbladder, pancreas, kidney, and other lesions.

　　1. Apple diet

　　Apples contain tannic acid and have an astringent effect. Wash an apple, steam it, eat the flesh or peel it and mash it into a puree for consumption, 30-60 grams each time, 3 times a day. Apple soup is also an auxiliary beverage for treating diarrhea. Chop the apple, add 250 milliliters of water and a small amount of salt, and you can also add 5% sugar, boil the soup to drink as tea, suitable for infants under 1 year old.

　　2. Yolk diet

　　Boil an egg, remove the shell and yolk, and melt the yolk in a pot over low heat to extract oil. Infants under 1 year old should take one yolk oil per day, divided into 2-3 doses, for 3 days as a course of treatment, for diarrhea, and it also has the effect of invigorating the spleen and stomach to stop diarrhea; the egg yolk mixed with a little flour and ginger slices steamed into an egg cake also has the same effect.

　　3. Chestnut paste diet

　　Use 3-5 chestnuts, remove the shell and crush them, add water to cook into a paste, add sugar to taste and eat, 2-3 times a day, with the effect of warming and stopping diarrhea.

　　1. Treatment

　　1. General treatment

　　Generally speaking, the most important aspect of treatment is to establish a solid therapeutic relationship between the doctor and the patient. The doctor should gain the patient's trust by thoroughly inquiring about the medical history and conducting a comprehensive and detailed physical examination. After the initial examination, the doctor should discuss differential diagnoses with the patient, including the possibility of functional dyspepsia. Reasonable diagnostic and examination steps should be recommended to the patient, and their concerns should be explained. After the diagnostic examination, the patient should be informed of the diagnosis of functional dyspepsia, and they should be educated, doubts should be eliminated, the tendency to 'over-examine' should be suppressed, and the focus should shift from finding the cause of symptoms to helping patients overcome these symptoms.

　　Doctors should explore the patient's life stressors, including those related to family, school, interpersonal relationships, and living environment. It is unlikely to change their living environment, so they should guide patients in reducing stress responses, such as physical exercise and good eating and sleeping habits.

　　It is also necessary to understand any recent changes in the patient's diet or medication. Carefully identify foods and medications that may worsen the patient's symptoms and stop using them.

　　2. Drug treatment

　　The efficacy of drug treatment for functional dyspepsia is not very satisfactory. So far, there is no specific medication that can completely alleviate symptoms. Moreover, the improvement of symptoms may also be related to the natural course of the disease, or the effect of placebo. Therefore, the focus of treatment should be on changing lifestyle habits and adopting positive coping strategies, rather than solely relying on medication. When symptoms worsen, drug treatment may be helpful, but the dosage should be minimized, and long-term use should only be considered when there is clear benefit.

　　The following is an introduction to the commonly used drugs for the treatment of functional dyspepsia:

　　(1) Antacids and Antisecretory drugs:

　　① Antacids: Antacids are the most widely used drugs in the treatment of dyspepsia. In Western countries, it is an over-the-counter drug. Some patients experience symptom relief after taking antacids, but there are also reports that antacids have similar efficacy to placebos in the treatment of functional dyspepsia.

　　Antacids (sodium bicarbonate, aluminum hydroxide, magnesium oxide, magnesium trisilicate) commonly used in China include Lon, compound aluminum hydroxide (Gushuping), Gudele (Ledegwei), magnesium aluminum bicarbonate (Gudaxi), and compound bismuth aluminum hydroxide. These drugs have a significant effect on alleviating symptoms such as hunger pain, acid regurgitation, and heartburn. However, the action time of the drug is short, and it needs to be taken multiple times. Long-term use may cause adverse reactions.

　　② Antisecretory drugs: Antisecretory drugs mainly refer to H2 receptor antagonists and proton pump inhibitors.

　　There are many reports on the treatment of functional dyspepsia with H2 receptor antagonists, and the efficacy of the drug is statistically significantly better than that of placebo. The main ones are cimetidine, 20-30mg/(kg·d), taken twice daily; ranitidine, 5-7mg/(kg·d), taken twice daily; famotidine, 0.6-1mg/(kg·d), taken twice daily, etc.

　　Omeprazole, a proton pump inhibitor, 0.6-0.8mg/(kg·d), taken once daily orally, can inhibit the H+-K+-ATPase of parietal cells, has a strong inhibitory effect on acid secretion, and lasts for a long time, suitable for patients who are ineffective with H2 receptor antagonists.

　　(2) Prokinetic drugs: According to clinical trials with control groups, it is now certain that metoclopramide (Ganfushi), domperidone (Metoclopramide), and cisapride are effective in eliminating the symptoms of functional dyspepsia. Domperidone (Metoclopramide) is more commonly used in pediatrics.

　　Metoclopramide (Ganfushi): It has central and peripheral dopamine antagonistic effects, and at the same time excites 5-HT4 receptors, promotes the release of endogenous acetylcholine, increases the coordinated movement of the gastric antrum and duodenum, and promotes gastric emptying. The pediatric dose is 0.2mg/kg per dose, taken 3-4 days, 15-20 minutes before meals. Due to the many adverse reactions, its clinical application is gradually decreasing.

　　Domperidone (Metoclopramide): An antiemetic drug that acts on peripheral dopamine receptors, can promote the emptying of solid and liquid in the stomach, inhibit the relaxation of the stomach, coordinate the movement of the gastric antrum and duodenum, relax the pylorus, thereby alleviating symptoms of dyspepsia. The pediatric dose is 0.3mg/kg per dose, taken 3-4 days, 15-30 minutes before meals. Children under 1 year of age should not take it due to the incomplete development of the blood-brain barrier function.

　　③ Cisapride: By promoting the release of acetylcholine at the postsynaptic endings of the parasympathetic ganglion fibers of the gastrointestinal muscularis layer, it enhances the lower esophageal sphincter tone, strengthens the propulsive movement of the esophagus, stomach, small intestine, and colon. The main effects on the stomach are to increase the contraction of the antrum and improve the coordination movement between the antrum and duodenum. Reducing the frequency of pyloric phase-specific contraction, making the gastric electrical activity tend to normal, thereby accelerating gastric emptying. The pediatric dose is 0.2mg/kg per time, taken 15-30 minutes before meals for 3-4 days. Clinical studies have found that this drug can significantly improve dyspepsia symptoms, but due to the adverse reactions to the heart, its application is limited.

　　④ Erythromycin: Although it is an antibiotic, it is also a motilin agonist, which can increase the contraction activity of the proximal and distal parts of the stomach, promote propulsive peristalsis, accelerate fasting and postprandial gastric emptying, and can be used for FD children.

　　(3) Gastric mucosal protective agents: These drugs mainly include colloidal bismuth, sucralfate, misoprostol, enprostil, double octahedral montmorillonite (Simeticon) and others. The clinical application of these drugs is mainly due to the possibility that the onset of functional dyspepsia may be related to chronic gastritis, and the patient may have weakened gastric mucosal barrier function.

　　(4) 5-HT3 receptor antagonists and opioid receptor agonists: These two types of drugs have a weak effect on promoting gastric emptying, and the principle of treating patients with functional dyspepsia is to regulate the visceral sensory threshold. However, there is no medication experience in pediatrics for this type of drug.

　　(5) Antianxiety drugs: Some people in China use low-dose doxepin combined with domperidone combined with psychological counseling to treat patients with functional dyspepsia, and found that it has a significant relieving effect on symptoms such as upper abdominal pain and belching, which is significantly improved compared to patients who do not use doxepin. Therefore, there is a certain clinical significance in the treatment of FD by using drugs to treat psychological disorders.

　　II. Prognosis

　　Mostly, by carefully finding the cause of the disease, gaining the trust and cooperation of the patient, and adjusting the treatment, the symptoms are relieved.