Short bowel syndrome

　　Currently, there are many causes of short bowel syndrome, which can be roughly understood as follows. After extensive small bowel resection due to various etiologies, the digestive and absorptive area of the small intestine suddenly and significantly decreases, and the remaining intestine cannot absorb enough nutrients to meet the physiological metabolic needs of the patient, leading to the whole body being in a state of malnutrition and electrolyte imbalance, followed by organ dysfunction, metabolic dysfunction, and decreased immune function, thus causing a series of syndromes. Adult short bowel syndrome is caused by the repeated resection of the small intestine due to recurrent diseases such as Crohn's disease, radiation-induced intestinal injury, or recurrent intestinal obstruction and intestinal fistula, or due to vascular diseases such as mesenteric vascular occlusion, acute intestinal volvulus, or traumatic vascular rupture and interruption, resulting in the resection of a large amount of small intestine due to ischemic necrosis.

　　In general, rarely seen situations include: due to the error in the surgical method, the gastrojejunal anastomosis is performed in the treatment of peptic ulcer, resulting in iatrogenic clinical symptoms similar to those after extensive small bowel resection. In children, it is mostly due to congenital factors, such as abdominal hernia, intestinal atresia, necrotizing enterocolitis, and so on. These can cause insufficient length of the small intestine, thus maintaining sufficient absorption of nutrients.

　　Short bowel syndrome can complicate the absorption disorders of individual nutrients such as vitamins, electrolytes, and trace elements, as well as various metabolic complications. The following will specifically introduce these for everyone.

　　1, Diarrhea

　　The causes of diarrhea after extensive resection of the small intestine include: the shortened passage time of food content, secondary to lactose and other carbohydrate absorption disorders.

　　2, Hypersecretion of gastric juice and peptic ulcer

　　Hypersecretion of gastric juice is an important feature after extensive resection of the small intestine. It not only causes severe peptic ulcer disease but also further damages the absorption function of short bowel syndrome, causing diffuse mucosal damage.

　　3, Nutritional disorders

　　After extensive resection of the small intestine, the absorption of nutrients including proteins, fats, and carbohydrates is impaired, leading to insufficient calories, weight loss, fatigue, and slow growth in children.

　　4, High oxalate in the intestine and renal calculi

　　The incidence of renal calculi increases after resection of the ileum and ileal diseases.

　　5, Excessive bacterial growth

　　Inflammatory bowel diseases such as Crohn's disease or radiation enteritis can lead to intestinal fistula, small intestinal stricture,短路 of the jejunum and ileum, and postoperative resection of the ileocecal junction, which can cause excessive bacterial growth in patients. After the短路 of the jejunum and ileum, due to increased stasis in the blind loop, it can cause excessive bacterial growth; patients who have had a resection of the ileocecal junction may be related to the loss of function of the ileocecal valve, which can lead to a large amount of colonic bacteria refluxing into the small intestine.

　　The symptoms of short bowel syndrome can generally be divided into three stages: the decompensation phase, the compensatory phase, and the late compensatory phase. The decompensation phase, also known as the first stage, refers to the early stage after a large amount of small intestine is resected. The remaining intestine not only cannot absorb water and nutrients but also loses the digestive juices secreted by the stomach, bile duct, and pancreas. Patients may experience varying degrees of diarrhea, with most patients not very severe. A few patients may have up to 2L of diarrhea per day, with the potassium content in the loose stools reaching 20mmol/L, leading to water, electrolyte, and acid-base imbalance and acid-base imbalance.

　　The compensatory phase, also known as the second stage, is when the body's homeostasis is stabilized after treatment, the frequency of diarrhea decreases, the function of the small intestine begins to compensate, the absorption function is enhanced, the loss of intestinal fluid gradually decreases, and the intestinal mucosa appears hyperplasia. The duration of this stage varies with the length of the remaining small intestine, the presence or absence of the ileocecal junction, and the compensatory function of the intestine, with the longest duration up to 2 years, usually around 6 months. The late stage of compensation, also known as the third stage, is when the intestinal function has certain digestive and absorptive functions after compensation. At this time, the method and amount of nutritional support have been standardized, but it is necessary to continue maintaining nutrition and preventing complications.

　　And if short bowel syndrome patients do not receive special nutritional support treatment, they will gradually develop malnutrition symptoms, including weight loss, fatigue, muscle atrophy, anemia, hypoalbuminemia, anemia, hyperkeratosis of the skin, muscle spasms, poor coagulation function, and bone pain, etc. Deficiencies of calcium and magnesium can enhance the excitability of nerves and muscles and cause tetany of the hands and feet. Long-term calcium deficiency can also lead to symptoms such as osteoporosis.

　　The only way to effectively prevent short bowel syndrome is to try to avoid excessive resection of the small intestine during surgery. If short bowel syndrome is found, medical treatment should be sought promptly to prevent the occurrence of complications.

　　Short bowel syndrome is a clinical syndrome caused by a decrease in the absorption area of the small intestine due to different reasons. Generally, the following examinations are needed for this disease:

　　1. Blood routine examination may show iron deficiency anemia or megaloblastic anemia in the patient.

　　2. Blood biochemical tests may show electrolyte disorders and acid-base balance disorders, negative nitrogen balance; plasma protein and lipids are reduced, and the content of lipids increases.

　　3. Thrombin can be reduced.

　　4. Absorption tests of sugar, protein, and fat in the small intestine can all be reduced.

　　5. If necessary, pancreatic function tests and urinary oxalate excretion determination can be performed.

　　6. If there is a suspicion of small intestinal contamination syndrome, small intestinal fluid bacterial culture and counting can be performed, and a positive result is considered if the count exceeds 10^7/ml.

　　7. X-ray barium meal examination can clearly determine the length of the remaining small intestine, the time for the passage of intestinal contents, and the condition of the intestinal mucosal folds. Multiple examinations can be used for comparative observation.

　　When the intestinal function is initially restored, low-protein, low-fat semi-liquid foods such as thin rice porridge, thin lotus root powder, fruit juice water, vitamin sugar water, carrot water, etc., should be selected. As the intestinal function is further restored, nutritionally balanced enteral nutrition preparations such as Ansu, Lishikang, etc., can be selected. Foods high in fat, fiber, and spicy刺激性, such as animal fats, celery, spinach, chives, garlic, chili, etc., should be avoided.

　　And most early patients with short bowel syndrome cannot eat by mouth, and need to be supplied with energy through parenteral nutrition. When the intestines enter the compensation period, the amount of diarrhea is controlled, and the intestinal function is initially restored, small amounts of isotonic, easily absorbable enteral nutrition preparations can be started, and the dosage can be gradually increased as the patient adapts and absorbs. Continuous infusion is beneficial for absorption and reduces the acceleration of intestinal peristalsis caused by push-in methods.

　　If the time for enteral nutrition exceeds 4 weeks, or if the patient has difficulty tolerating the discomfort of placing a nasointestinal tube, percutaneous endoscopic gastrostomy or percutaneous endoscopic jejunostomy can be performed. At the same time, as the nutritional status gradually improves, parenteral nutrition can be gradually reduced until all enteral nutrition is applied. After the enteral nutrition can be well adapted, special oral nutritional supplements can be added on the basis of enteral nutrition, and attention should be paid to adding vitamins, trace elements, and supplementing electrolytes. The transition from enteral nutrition to regular diet also requires a step-by-step approach, and should not be rushed.

　　And the time for the intestines to compensate to the point where they can tolerate enteral nutrition without parenteral nutrition is roughly three to six months, and it may take longer to be completely cured.

　　The treatment of short bowel syndrome can be divided into two stages: early and late. The late stage includes compensation period and late compensation period. The following is a specific introduction to the treatment of this disease:

　　1. Early treatment

　　Generally lasting for 4 weeks, mainly to stabilize the patient's internal homeostasis and provide nutritional support, reduce gastrointestinal secretion and bile stimulation. The focus is on controlling diarrhea and preventing excessive loss of gastrointestinal fluid, leading to imbalance of internal homeostasis and the patient entering peripheral circulatory failure. It is necessary to supplement fluids and electrolytes to maintain acid-base balance and supplement trace elements and vitamins, and to start parenteral nutrition.

　　2. Late treatment

　　The main purpose is to maintain homeostasis, try to maintain the patient's nutrition and promote intestinal function compensation, improve intestinal absorption and digestion function. After early treatment, the decompensation period transitions to the compensation period and the late compensation period. The duration of the compensation period varies with the length of the residual intestinal segment and the body's compensatory ability, ranging from a few months to 1-2 years. Generally, 2 years is considered, and beyond 2 years, few patients can further improve their intestinal compensatory function.

　　Nutritional support is the most important and basic treatment method for short bowel syndrome. From the onset of short bowel syndrome, it is necessary to start parenteral nutritional support. Nutritional support is not only to maintain nutrition but also has the role of promoting intestinal mucosal hyperplasia and compensation. Enteral nutrition is superior to parenteral nutrition in promoting intestinal mucosal compensation. Intestinal rehabilitation treatment is to promote intestinal function compensation, so that more patients can get rid of parenteral nutrition. It was proposed in 1995. It should be used in the early stage of intestinal compensation; it is better for relatively young patients. And the effect is also good for those with longer residual small intestine or those who retain the ileocecal junction.

　　If there is still a severe short bowel syndrome or long-term no improvement in small intestinal adaptation after non-surgical treatments such as intestinal rehabilitation, surgical treatment can be considered.

　　Surgical methods to slow down intestinal transport: such as inversion of small bowel segments, interposition of retrograde intestinal segments, interposition of colonic surgery, artificial construction of sphincters or valves.

　　Surgical methods to increase the surface area of the intestinal tract: such as small bowel resection and extension, construction of intestinal loop loops, and longitudinal incision of small bowel loops to extend the intestinal segment.

　　Small intestine transplantation: it should be a reasonable way to treat short bowel syndrome, but due to the high rejection rate, frequent and severe infections, poor intestinal function and slow recovery, its success rate is far lower than that of other solid organ transplants. It is suitable for patients who need to permanently rely on total parenteral nutrition, and most patients with long-term total parenteral nutrition have liver damage, so some authors also propose small intestine-liver combined transplantation.