Pyloric stenosis

　　Pyloric stenosis can be caused by local inflammation and edema of the ulcer or spasm of the pyloric sphincter, or due to scars formed during the healing process of the ulcer. Both factors can coexist, but one factor is usually predominant. Once obstruction occurs, food and gastric juice accumulate, cannot pass through the pylorus into the small intestine, and may even cause vomiting. This not only affects the normal digestion and absorption of food but can also cause a large amount of abnormal loss of water and electrolytes, thereby causing a series of pathophysiological changes both locally and systemically.

　　Pyloric stenosis often forms gradually, that is, it gradually worsens from partial obstruction to complete obstruction. In the early stage of obstruction, in order to allow the chyme to enter the duodenum, the gastric peristalsis is enhanced, the muscular layer of the gastric wall is compensatorily hypertrophied, but the stomach does not significantly expand. As the obstruction continues to worsen, although the stomach has strong peristalsis, it is difficult to overcome the resistance of the pylorus. The stomach gradually expands, the peristalsis weakens, the gastric wall relaxes, and the stomach retains the chyme, showing bag-like expansion.

　　The course of pyloric stenosis is long, and patients gradually show general weakness, progressive emaciation, weight loss, oliguria, constipation, and sometimes psychiatric symptoms and cramps of the hands and feet. Pyloric stenosis is usually the most common complication of peptic ulcer disease, followed by strangulated intestinal obstruction. This disease is one of the acute abdomen diseases, and it often needs to be differentiated from diseases such as perforated peptic ulcer, acute severe pancreatitis, gallbladder perforation, acute appendicitis, or appendiceal perforation.

　　The specific symptoms of pyloric stenosis are vomiting of food from the previous night, whether accompanied by pain and the severity of vomiting are related to the location of the ulcer and the cause of the obstruction. Generally, patients have a long history of ulcer disease, and as the lesions progress, the stomach pain gradually worsens, with symptoms such as belching and regurgitation. Patients often become厌食 due to stomach bloating, and antacid drugs become ineffective. The stomach gradually expands, the upper abdomen is full, and there are mobile masses. Due to increased vomiting, dehydration becomes more severe, and weight loss occurs. Patients may have headaches, fatigue, thirst, but also aversion to food, and in severe cases, may experience collapse. Due to excessive loss of gastric juice, cramps of the hands and feet may occur, even convulsions. The urine output decreases day by day, and finally, coma may occur.

　　The signs and symptoms of pyloric stenosis are emaciation, fatigue, dry skin and loss of elasticity, and signs of vitamin deficiency may appear. The lips are dry, the tongue is dry with fur, the eyes sink in, and there is significant distension in the upper abdomen, with visible gastric patterns and gastric peristalsis moving from left to right. Percussion over the upper abdomen shows tympany and splashy sounds, and the sound of water passing through can be heard, but it is very rare. In cases of ulcer disease complicated with pyloric stenosis, there may be spastic obstruction, inflammatory edematous obstruction, scar obstruction, and adhesive obstruction.

　　Patients with pyloric stenosis should avoid using anticholinergic or antimuscarinic drugs to prevent increasing the tension of the gastrointestinal smooth muscle and exacerbating the obstruction. Patients can consume clear liquid diet, and all foods with particles and milk and other gas-producing liquids should not be consumed. Foods with particles include vegetables, meats, etc. In addition to diet, limiting smoking and alcohol, maintaining adequate sleep, and moderate exercise are basic effective methods.

　　Pyloric stenosis often leads to significant blood hypercoagulability due to dehydration, and mild anemia, hypoalbuminemia, decreased serum potassium, sodium, and chloride levels may occur when the course is long. When there is low chloride and hypokalemia alkalosis, the carbon dioxide combining power increases, the blood gas analysis pH is greater than 7.45, B.E is greater than +3, and PCO2 may decrease. Severe patients may have increased blood urea nitrogen or non-protein nitrogen due to decreased urine output. If the patient has potassium deficiency, the urine may become acidic. The main clinical examination methods for pyloric stenosis include the following aspects:

　　1. Gastric content aspiration

　　It is a simple and reliable method to determine whether there is gastric retention. If more than 300ml of gastric juice can be aspirated 4 hours after a meal, or more than 200ml of gastric juice can be aspirated in the morning after a night of fasting, it indicates the existence of gastric retention. If the gastric juice contains retained food, it supports the diagnosis of pyloric stenosis.

　　2. Saline loading test

　　After aspirating the gastric juice, 750ml of isotonic saline is injected, and the entire stomach contents are aspirated 30 minutes later. If the amount reaches more than 400ml, it can be considered that there is a pyloric stenosis.

　　3. X-ray examination

　　The abdominal X-ray film shows an enlarged gastric bubble. If an upper gastrointestinal barium meal examination is performed, it can clearly diagnose the condition and understand the nature of the obstruction. However, for patients with severe obstruction, due to a large amount of food retained in the stomach, it often cannot be determined the nature of the obstruction. For such patients, it is advisable to perform gastric decompression first, and then perform a barium meal examination after the stomach contents are aspirated, which is often helpful for diagnosis.

　　4. Fiberoptic gastroscopy

　　Fiberoptic gastroscopy not only determines the presence or absence of obstruction but also determines the nature of the obstruction, and can perform brushing cell examination or biopsy to clarify the diagnosis. If gastric retention affects the examination, it can be suctioned under direct vision before re-examination.

　　For patients with pyloric stenosis, the diet should mainly consist of easily digestible foods, avoid irritant substances, eat to seven parts full, maintain regular and normal eating habits. Do not eat irregularly, and porridge and noodles can be eaten. Avoid cold and stimulating foods and difficult-to-digest foods, as well as fried foods. Those with excessive gastric acid should consume more protein, and those with duodenal ulcer should avoid irritant foods. People with excessive gastric acid should pay attention to inhibiting gastric acid secretion in daily life, avoiding overeating and stimulating foods.

　　The main methods of Western medicine for treating pyloric stenosis include the following aspects:

　　1. Correct water, electrolyte, and acid-base balance disorders

　　For patients with a long history and severe conditions, it should be first corrected for dehydration, electrolyte and acid-base balance disorders.

　　4. Mild patients: Due to pyloric stenosis caused by peptic ulcer disease, the gastric acid level is generally high, and more chloride is lost than sodium after vomiting, so the fluid replacement can be done entirely with normal saline. After the urine output increases to 40 to 50 ml/h, potassium chloride can be supplemented intravenously. This method can often correct dehydration and mild hypochloremic alkalosis.

　　5. Severe patients: If the bicarbonate combined capacity exceeds 30 mmol/L or the blood chloride level is below 85 mmol/L, in addition to correcting dehydration, 2% ammonium chloride solution can be administered intravenously. However, this solution not only affects the liver but also has poor therapeutic effects and is now rarely used. In recent years, 0.1 mol HCl solution is often used for intravenous infusion to treat hypochloremic alkalosis, with good results. The amount of chloride supplementation can be calculated based on the blood Cl- measurement. The hydrochloric acid solution should be infused slowly into the vena cava through a venous catheter, and should be completed within 24 hours. During the infusion, isotonic saline and potassium chloride solution should be added according to the loss of Na+ and K+, and K+, Na+, Cl-, and bicarbonate combined capacity should be re-measured every 4 to 6 hours to adjust the treatment plan in time.

　　2. Improve Nutrition

　　Patients with pyloric stenosis usually have poor nutritional status due to long-term vomiting, so in addition to correcting dehydration and electrolyte disorders, sufficient calories should be supplied to prevent excessive consumption of body fat and protein. However, the heat supply from general intravenous fluid administration is limited daily, so for patients with severe conditions and poor nutrition, total parenteral nutrition should be provided.

　　3. Gastrointestinal Decompression

　　Effective gastrointestinal decompression not only can relieve gastric retention, but also can improve the blood circulation of the stomach itself and the inflammation of the mucosa. For some severe patients, saline can be used for gastric lavage to facilitate the rapid recovery of the mucosa, which is beneficial for surgery or further examination. If the obstruction is due to edema or spasm, the symptoms can be relieved as the edema subsides after decompression.

　　4. Surgical Treatment

　　Pyloric stenosis is an absolute indication for surgical treatment of ulcer disease, but the choice of surgical method should be based on the patient's condition, equipment conditions, and technical strength. The principle should be safety, effectiveness, and the ability to cure ulcers.

　　1. Preoperative Preparation: Preoperative preparation should be sufficient, correct water and electrolyte, acid-base balance disorders, improve nutritional status, wash the stomach for more than 3 days. Eliminate local inflammation and edema of the stomach.

　　2. Surgical Methods:

　　(1) Gastricjejunal Anastomosis: The method is simple, the short-term effect is good, the mortality rate is low, but due to the high incidence of anastomotic ulcers after surgery, it is now rarely used. For elderly patients with weak physical condition, low gastric acid, and extremely poor general condition, it can still be considered to choose.

　　(2) Partial Gastrectomy: If the patient's general condition is good, this is the most commonly used surgical method in China.

　　(3) Vagotomy: Vagotomy combined with partial gastrectomy or vagotomy combined with gastric drainage is more suitable for young patients.

　　(4) High Selective Vagotomy: In recent years, there have been reports on high selective vagotomy and pyloroplasty, which have achieved satisfactory results. Patients with pyloric stenosis should be well prepared before surgery. From 2 to 3 days before surgery, perform gastrointestinal decompression, use warm saline to wash the stomach daily to reduce gastric tissue edema. Blood transfusion, fluid infusion, and improvement of nutrition, correction of water and electrolyte disorders.

　　Surgical treatment for gastric ulcer with pyloric stenosis still mainly adopts the Belsey Mark IV operation for subtotal gastrectomy.Selective vagotomy with pyloroplasty (SVA), Billroth I or II anastomosis can also be considered. The long-term postoperative efficacy is excellent, and the recurrence rate of ulcers is low. For patients with DU complicated with pyloric stenosis, in addition to the above operations, expanded parietal cell vagotomy with pyloric dilatation or additional drainage can also be chosen. Simple gastric jejunostomy is not suitable to be used, because the recurrence rate (anastomotic ulcer) is as high as 30% to 50%. If short-term medical treatment is ineffective, it indicates that scar contraction is the main factor causing pyloric stenosis. After surgical treatment to relieve obstruction, more than 90% can achieve satisfactory efficacy.