small bowel resection

The small intestine refers to the intestine between the pylorus and the cecum, including the duodenum, jejunum and ileum. The jejunum and ileum are the main part of the small intestine, commonly known as the small intestine. The jejunum and ileum are the largest and highly active organs in the abdominal cavity. Starting from the Treitz ligament (duodenal jejunum), it is curved in the mid-abdomen and lower abdomen, partially covered by the omentum and colon. If the patient has no history of abdominal surgery, the small intestine taken from the left upper abdomen during surgery is mostly the jejunum, and most of the pelvic cavity is the ileum. There is no obvious dividing line between the jejunum and the ileum, but there are some differences in structure. At the time of surgery, these differences can be used to identify the empty and ileum. The intestine has a certain degree of flexibility, so the length measured in the living body and the specimen is inconsistent. The result of the general measurement is empty and the ileum is 6m long. It is now considered that the most suitable method is to place a thin polyethylene tube from the nose so that it naturally reaches the ileocecal area and measure its length. The length of the empty and ileum was measured by this method to be 2.6 m. 2/5 of the upper part of the small intestine is the jejunum, and the lower part is 3-5. The small mesentery is very wide, attached to the posterior wall of the left abdomen of the second lumbar vertebrae, and obliquely to the right to the right ankle joint. The mesentery contains blood vessels, nerves, lymphatic vessels, lymph nodes and fat. The mesenteric attachment prevents twisting and affects circulation. At the time of surgery, the proximal and distal ends of the free intestine segment can be distinguished according to the direction of the mesentery. The distance from the base of the mesentery to the intestine is the shortest at the beginning of the small intestine, and the distal part of the ileum is also short, while the part that spans the spine is the longest, generally not exceeding 20-25 cm. The blood supply to the small intestine comes from the superior mesenteric artery, which is the second largest branch of the abdominal aorta. The superior mesenteric artery passes through the hook-like projection of the pancreas, spans the third segment of the duodenum, enters the small mesenteric root, and then divides the right colon artery, the ileal artery and 10 to 20 small arterial branches (Figure 1.6). .2-0-1). The first two arteries supply the ascending colon, cecum, and terminal ileum through the retroperitoneal or mesenteric root. Therefore, when the superior mesenteric artery is damaged or infarcted, the jejunum, ileum, ischemic necrosis in the jejunum, part of the colon or part of the jejunum and ileum may be caused by the height of the damaged part. The branch of the small intestine artery is located in the small mesentery, forming an anastomotic network (arterial arch), and then the straight branch of the arterial arch reaches the intestinal wall. The upper mesenteric artery arch of the small intestine is only one (primary bow), the straight branch is longer, the surrounding fat is less, and the more distal the small intestine is the arterial arch. The arterial anastomosis was divided into 2 grade and 3 grade arches by the primary arch, and the arterial straight branch was shorter (Fig. 1.6.2-0-2). There is also more fat in the mesentery. At the mesenteric margin, the blood vessels branch again. The blood vessels of the intestinal wall run parallel to the annular muscle layer, passing through the serosa, muscle layer and submucosa. After the main arterial branches and straight branches are destroyed, the intestines supplied by these blood vessels are prone to necrosis. The distribution of the small intestine vein is roughly the same as that of the artery. Finally, it is combined into the superior mesenteric vein. It is parallel to the superior artery and merges with the splenic vein at the back of the neck to form the portal vein. In the case of superior mesenteric vein injury or embolism, it can also cause intestinal venous congestion, necrosis and peritonitis. The intestinal wall of the small intestine is divided into three layers of serosa, muscle and mucous membrane. The muscle is divided into the outer longitudinal muscle and the inner ring muscle. The submucosa is a strong elastic fiber and connective tissue. Regardless of which method is used to suture the intestinal wall, the suture must pass through this layer. There are polymeric lymph nodes and Peyer's patches in the submucosal layer of the small intestine, especially in the ileum. The lymph of the small intestine flows into the intestinal wall, adjacent to the vascular arch and the upper mesenteric artery trunk and other three parts of the lymph nodes, and then enters the chyle pool. The main physiological function of the small intestine is digestion and absorption. In addition to pancreatic juice, bile fluid and gastric juice can continue to digest in the small intestine, small intestinal mucosa can also secrete alkaline intestinal fluid containing a variety of enzymes. The main one is the polypeptide enzyme (guteptidase). It transforms a polypeptide into an amino acid that can be absorbed by the intestinal mucosa. After being decomposed into glucose, amino acids and fatty acids in the small intestine, the chyme is absorbed by the small intestine mucosa. There is a lot of fluff on the small intestine mucosa. Each of the villi is covered by a plurality of columnar epithelial cells, and contains a capillary vasospasm and a lymphatic vessel (chylomicron), thereby greatly increasing the absorption area and constituting an absorption area of nearly 100,000 m2. Glucose, amino acids, and 40% fatty acids are absorbed by capillaries and reach the liver through the portal vein. The remaining 60% of the fatty acids are absorbed by the chyle tube and reach the chyle and thoracic duct. In addition to food, gastric juice, bile fluid, pancreatic juice, electrolytes in intestinal fluid, and a large amount of electrolytes ingested are also absorbed into the blood circulation in the small intestine. After the small intestine is removed, the absorption of nutrients will be affected. The worst absorption is fat, followed by protein. Carbohydrates are nutrients that are easily absorbed. According to clinical practice, the jejunum and ileum are kept more than 100cm, and there is a ileocecal part. After the compensation of the body, the nutrient digestion and absorption can be maintained. The terminal ileum has a good absorption function for proteins, fats and carbohydrates, and has a specific absorption function for certain trace substances (copper, vitamin B12) and bile. Therefore, after a large number of small intestine resections, although the length of the resection is equivalent, the cases of malnutrition in the ileum are more obvious. The small intestine is the place where immunoglobulins are produced, especially IgA. It is generally thought to be produced by plasma cells of laminal propria. The small intestine can also produce cholecys tokinin, pancreozymin, enterroglucagon, VIP vasoactive intestinal peptide, GIP gastric inhibitory polypetide, growth. Substances such as somatostatin. These substances directly affect the functions of other organs of the digestive system such as the gallbladder and the pancreas. The intestinal mucosa also has a barrier function that blocks bacteria and toxins in the intestinal lumen from entering the lymphatic system or portal vein across the intestinal wall. The small intestine is dominated by the autonomic nervous system. The sympathetic nerve fibers are separated from the ninth and tenth spinal segments and enter the superior mesenteric ganglia. The posterior tibial nerve is accompanied by the superior mesenteric artery into the small intestine. The parasympathetic ganglia fibers are connected to the neurons of the intestinal plexus by the vagus nerve. Stimulation of parasympathetic nerves increases the tension and movement of the intestines and secretion of the gut glands. Stimulating the sympathetic nerve, the tension of the intestine is relaxed, the movement is inhibited, and the blood vessels contract. Intestinal nerves include the Auerbach plexus in the iliac muscle and the Meissner plexus in the submucosa. Stimulation of the intestinal muscle plexus causes contraction of the intestinal smooth muscle, stimulating the submucosal plexus to inhibit smooth muscle. The muscles of the small intestine have two types of motion: segmental contraction and peristalsis. The former is a partial circumference contraction. The upper small intestine contracted about 9 times per minute, and the distal small intestine contracted 11 times per minute. This action causes the contents of the intestine to be agitated to contact a wider range of mucosa. Peristalsis is the top-down contraction of the small intestine, 1 or 2 times per minute, 1 centimeter. In the process of digestion and absorption, the small intestine has a top-down circular contraction, starting from the stomach or the duodenum, moving 6 to 8 cm per minute, each lasting 4 to 5 minutes. The movement of the small intestine is regulated by myogentic factors, neurogenic factors and hormonal factors. In summary, the small intestine is the main organ for the body to absorb nutrients, and it has an extremely powerful compensatory function. Despite this, surgeons should consider the importance of these functions when dealing with small bowel lesions, and try to retain the intestines that can be retained. Treatment of diseases: malignant tumors Indication Partial small intestine resection is a type of surgery commonly used in abdominal surgery. It is used to treat resectable small bowel lesions such as benign, malignant tumors, intestinal damage, intestinal inflammatory lesions, and intestinal ischemic lesions. Contraindications Severe peritonitis, suspicious blood supply to the intestine, and unstable intraoperative vital signs should be considered as relative contraindications for surgery. Simple transitional procedures such as stoma, external bowel, and short-circuit surgery can be used. Preoperative preparation Gastrointestinal decompression before surgery, correction of body fluids and electrolytes, acid-base imbalance, if necessary, add albumin or blood. Non-emergency surgery, taking fluid 2 days before surgery. Prepare the bowel with antibiotics before surgery. Surgical procedure 1. Use any incision in the abdomen More commonly used is the rectus abdominis incision. 2. Lifting the selected intestine segment and discriminating the distribution of the mesenteric supply vessels. The mesenteric vessels are fan-shaped incision according to the extent of intestinal resection. The blood vessels are cut by a vascular clamp and are ligated or sutured without absorption. . The blood vessels in the mesenteric root are thicker and are the main supply branch. They should be double-ligated to prevent large bleeding from falling off. When cutting the mesenteric vessels, it is necessary to observe the extent of supply of these blood vessels so as to avoid excessive blood supply to the cut ends of the retained intestinal tubes. When the intestine segment with malignant lesions is removed, the lymph nodes of the corresponding mesentery must be removed along with the mesentery. Sometimes, in the removal of the intestine of a non-malignant lesion, the mesenteric vessel can be cut and ligated along the intestine for ease of surgery or to preserve the corresponding mesangium. 3. After the mesentery is properly separated, the intestines and clamps are used to clamp the distal and proximal ends of the intestine resection line by about 5 cm. After clamping one end, the contents of the intestine are squeezed to the other end, and the other end is clamped with the intestinal clamp, so that the removed intestinal tube does not contain much content, and the intestinal fluid overflows from contaminating the surgical field when the intestinal tube is cut off. The intestine can be clamped with a dental vascular clamp according to a predetermined intestinal resection line. The toothed forceps can be perpendicular to the longitudinal axis of the intestine or at 15°, and the mesenteric margin is slightly removed to ensure blood supply. The resection point of the mesenteric margin can be about 1 cm away from the mesangial margin of the preserved blood vessel, that is, the mesenteric margin of the mesenteric canal can be sutured at the mesangial margin when the anastomosis of the mesenteric margin is 1 cm. Gain the gauze at the site where the bowel is to be cut and isolate the surrounding tissue to reduce contamination. The intestine is cut along the vascular clamp, and the resected intestinal fistula and mesentery are removed from the operating table. The mucosa of the cut end of the intestinal fistula is coated with iodophor or thiomersal to disinfect. When there is active bleeding in the intestinal wall or the mesenteric margin at the cut end, the line can be 3-0 not absorbed, and the hemostasis can be ligated. complication The most common complications after partial resection and anastomosis of the small intestine are hemorrhage, peritonitis, and intestinal anastomotic leakage.