Superior mesenteric artery compression syndrome

　　The anatomical characteristics of the duodenum, superior mesenteric artery, and abdominal aorta are closely related to the occurrence of superior mesenteric artery compression syndrome.

　　Under normal circumstances, the duodenum is located between the abdominal aorta and its anterior branches, including the superior mesenteric artery, forming an angle. The superior mesenteric artery runs diagonally in front of the duodenum, with the celiac artery and spine behind it. The normal angle as determined by angiography is 47-60°. Abnormalities such as an overly long or short mesentery, visceral prolapse, forward inclination of the spine, and variations in the superior mesenteric artery itself can cause this condition.

　　The mesentery is pulled downward, making the angle smaller, often <6-25°, and compressing the horizontal part of the duodenum, forming a stricture of the intestinal tract, and causing duodenal obstruction symptoms.

　　The complications of superior mesenteric artery syndrome include acute gastric dilatation, intestinal necrosis, duodenal perforation, upper gastrointestinal hemorrhage, portal vein thrombosis, and others.

　　1. Acute gastric dilatation: Acute gastric dilatation refers to a syndrome caused by the short-term accumulation of a large amount of gas and fluid, resulting in the severe expansion of the stomach and the upper segment of the duodenum. It is usually a severe complication of certain surgical diseases or anesthetic surgery.

　　2. Intestinal necrosis: Intestinal necrosis, also known as acute hemorrhagic necrotic enteritis, can be caused by many reasons. Once intestinal necrosis occurs, symptoms such as abdominal pain, hematochezia, nausea, and vomiting may occur. Nausea and vomiting often occur simultaneously with abdominal pain and diarrhea. The vomit may be yellowish water-like, coffee-like, or bloodwater-like, and bile may also be vomited.

　　3. Duodenal perforation: The local manifestation of duodenal perforation is a localized circular or elliptical defect in the duodenal wall, and its main clinical manifestations are upper abdominal pain, belching, and acid regurgitation, which are prone to recurrence and present a chronic course.

　　4. Upper gastrointestinal hemorrhage: The clinical manifestations of upper gastrointestinal hemorrhage are massive hematemesis or melena; in adults, if the amount of bleeding in one episode is above 800ml, accounting for 20% of the total blood volume, shock signs may appear.

　　5. Portal vein thrombosis: The formation of portal vein thrombosis can lead to liver cirrhosis or segmental atrophy, and if it is combined with mesenteric vein thrombosis, it can be acute and fatal. About one-third of patients have a slow formation of portal vein thrombosis, which can form collateral circulation, and the portal vein can be revascularized, but it eventually progresses to portal hypertension.

　　Superior mesenteric artery syndrome can occur at any age, and it is more common in middle-aged and young adults with slender and tall body types. According to the onset situation, it can be divided into acute and chronic types. The specific symptoms are as follows:

　　Superior mesenteric artery syndrome

　　The course of superior mesenteric artery syndrome is generally long, with intermittent and recurrent attacks, mainly manifested as postprandial upper abdominal stuffiness, nausea, and vomiting, with the vomit containing bile and the food ingested. It may be accompanied by abdominal pain, and the symptoms may alleviate or disappear after vomiting. The onset of symptoms is related to body position: patients often change their position to alleviate pain, such as lying on the side, prone position, chest-knee position, forward sitting position, or placing both knees under the chin, as these positions can increase the angle between the superior mesenteric artery and the abdominal aorta, thereby reducing the pressure on the duodenum. Conversely, supine position can worsen the symptoms. During the attack, physical examination may show gastrointestinal shape and peristalsis waves, mild tenderness in the upper abdomen, and occasionally, the sound of gurgling water may be heard. During the remission period, there may be no obvious signs. Patients with a long course and severe condition are more likely to have emaciation, dehydration, and malnutrition. Further reduction of fat pads can make the compression more severe, forming a vicious cycle.

　　Acute superior mesenteric artery syndrome

　　Acute superior mesenteric artery syndrome is less common, and the etiology is often related to trauma and iatrogenic factors. The symptoms are similar to those of chronic cases, but they are more persistent and severe, with frequent and large-volume vomiting. Physical examination may reveal gastric dilation, more obvious gastrointestinal peristalsis waves, and splash sounds than in chronic cases. At present, the complications of superior mesenteric artery syndrome reported include acute gastric dilation, intestinal necrosis, duodenal perforation, massive upper gastrointestinal bleeding, portal vein thrombosis, and portal vein gas.

　　The following are the daily preventive and nursing measures for superior mesenteric artery syndrome:

　　Nursing care for diet: After surgery, patients with superior mesenteric artery syndrome should strictly follow the doctor's orders to fast. After the intestinal peristalsis recovers, start with water, high-protein, high-vitamin, and low-fat liquid food after anal exhaust, and gradually transition to semi-liquid and regular food. Observe the patient for symptoms such as nausea, vomiting, abdominal pain, and bloating after eating. If some patients who have undergone duodenal ring drainage surgery experience nausea or a small amount of vomiting after eating, they should be briefly introduced to the surgical method. Explain that the appearance of these symptoms is mainly due to the incomplete recovery of the function of the reconstructed intestine after surgery, strong retrograde peristalsis of the duodenum, multiple anastomoses, and temporary inability to adapt to the postoperative gastrointestinal anastomosis. After 3 to 6 months, the symptoms will gradually subside and recover.

　　Nursing care for preventing postoperative complications: (1) Keep the patient's respiratory tract unobstructed. If there are symptoms such as coughing and expectoration, use gentamicin 80,000 U + chymotrypsin 5mg for nebulizer inhalation, 2 times a day, and can also be added with Mucosolvan intravenous push to dilute sputum and facilitate expectoration, prevent pulmonary infection, and prevent incision opening due to severe cough; (2) The doctor should assist the patient in early ambulation to increase lung capacity, prevent pulmonary infection, promote intestinal peristalsis, prevent intestinal adhesions, promote blood circulation, and prevent bedsores and the formation of venous thrombosis.

　　1. Barium meal X-ray examination There is marked dilation of the stomach and duodenum, the pylorus is patent, and there is a sudden obstruction in the horizontal part of the duodenum, with obvious retrograde peristalsis. After supine or left lateral position, the retention of the duodenum disappears.

　　2. Angiography examination Angiography of the superior mesenteric artery can show the anatomical angle relationship between the superior mesenteric artery and the aorta. Usually, the angle between the superior mesenteric artery and the aorta is less than 25°.

　　3. Laboratory examination Generally, there is no specificity. Long-term inability to eat normally can cause anemia, hypoproteinemia, and other abnormalities.

　　1. Pay attention to dietary hygiene and prevent ascariasis.

　　2. Individuals with a history of abdominal trauma or abdominal surgery should pay attention to abdominal exercise and timely treatment to prevent the occurrence of intestinal adhesions.

　　3. Elderly and weak individuals should maintain smooth defecation regularly.

　　The health maintenance methods for the above intestinal obstruction have been proven to be effective through practical testing. Everyone should not ignore them. Of course, after mastering the health maintenance methods for intestinal obstruction, it is essential to actively consult relevant experts to maximize the recovery of everyone's health.

　　(1) Easy-to-digest foods that promote defecation. Such as vegetables: kelp, pork blood, carrots, etc.; fruits: hawthorn, pineapple, papaya, etc.; eating more fibrous foods such as various vegetables, fruits, brown rice, whole grains, and beans can help defecate, prevent constipation, stabilize blood sugar, and lower blood cholesterol.

　　(2) It is advisable to eat light and nutritious liquid foods, such as rice porridge, vegetable soup, lotus root powder, egg flower soup, and noodles, etc;

　　(3) It is advisable to eat foods rich in protein and iron, such as lean meat, fish and shrimp, animal blood, animal liver and kidney, egg yolk, bean products, and jujube, green leafy vegetables, sesame paste, etc;

　　(4) It is advisable to eat processed or cooked food, which is conducive to mastication and digestion. Whole eggs can be eaten 1-2 times a week. Dairy products and their products, root tuber crops, meat, fish, bean egg foods, vegetables, fruits, and oils are the six major food categories, which should be consumed in a diverse manner to fully obtain various nutrients.

　　(5) Choose vegetable oils, and most often use methods such as boiling, steaming, mixing, roasting, grilling, pickling, and braising; avoid high-cholesterol foods such as fatty meat, offal, fish eggs, butter, etc.

　　In addition to the superior mesenteric artery compression syndrome caused by factors such as aneurysms that require immediate surgery or interventional treatment, conservative treatment should be adopted first during the acute attack period, including fasting, gastrointestinal decompression, maintaining water, electrolyte and acid-base balance, and nutritional support treatment. Total parenteral nutrition may be used when necessary. Antispasmodic drugs such as atropine and anisodamine and acid suppressants can be used to control gastrointestinal symptoms as appropriate.

　　Antidepressants (paroxetine) may be used for patients with anxiety and depression due to long-term illness, which can improve the clinical symptoms of the patients and improve the quality of life. After the symptoms are relieved, multiple small portions of liquid diet can be gradually given, and body position therapy can be used after meals, taking a lateral position, prone position, or chest-knee position and raising the bed feet.

　　If there is no asymptomatic recurrence, diet can be gradually increased, the number of meals can be reduced, and a girdle or abdominal belt can be used when getting out of bed to prevent visceral prolapse; improve nutrition, strengthen abdominal muscle exercises, and correct kyphosis. After the patient's nutritional status improves, the fat tissue between the superior mesenteric artery and the abdominal aorta can fill in and the angle can increase, which can lead to long-term remission or cure of the disease.