nutritional disorders
Metabolic and Bariatric Surgery
Procedures for Bariatric Surgery
The most common metabolic and bariatric procedures performed in the United States include Sleeve gastrectomy None Roux-en-Y gastric bypass (RYGB) surgery None Revisional procedures None Biliopancreatic diversion with a duodenal switch (BPD-DS) None Single anastomosis duodeno-ileal bypass with sleeve gastrectomy (SADI-S) None Endoscopic procedures None Adjustable gastric banding None Procedures such as the vertical banded gastroplasty or adjustable gastric banding are rarely used. Bariatric surgeons should be familiar with historical procedures because surgical complications can develop at any time—months to years—after surgery ( Procedures references ). Despite a growing percentage of the population with obesity, metabolic and bariatric surgery remains underused. Fewer than 1% of patients who qualify for surgery have the procedure. Telemedicine has allowed greater access to preoperative consultation; nonetheless, overall rates remain low ( Procedures references ). release [incretin effect]) that appear to contribute to the rapid remission of Diabetes Mellitus (DM) . After RYGB (particularly) or sleeve gastrectomy, levels of gastrointestinal hormones, such asglucagon-like peptide-1 (GLP-1) and peptide YY (PYY), are increased, possibly contributing to satiety, weight loss, and remission of diabetes. Increasedinsulinsensitivity is evident immediately postoperatively, before significant weight loss occurs, suggesting that neurohormonal factors are prominent in remission of diabetes. A change in gut microbiome may also contribute to changes in weight after RYGB. Metabolic and bariatric surgery reduces risk of mortality caused by cardiovascular disorders, diabetes, and cancer. Sleeve gastrectomy is the most commonly used metabolic and bariatric surgical procedure in the United States. About 80% of the stomach is removed, creating a tubular stomach passage that resembles a banana. The resulting sleeve holds less food and thus reduces the number of calories consumed. Patients also experience less hunger, which correlates with decreased levels of ghrelin and other neurohormonal alterations. The procedures is technically simpler than bypass procedures and can be done as the first step toward a biliopancreatic diversion with duodenal switch (BPD-DS) or Single anastomosis duodeno-ileal bypass with sleeve gastrectomy (SADI-S) (SADI-S). Sleeve gastrectomy does not alter the small intestine. Rare but serious complications include sleeve leakage and bleeding. Patients may also experience worsening or new-onset Gastroesophageal Reflux Disease (GERD) (GERD). RYGB is considered a restrictive and malabsorptive procedure. A small part of the proximal stomach is detached from the rest, creating a stomach pouch of<30 mL. Food bypasses part of the remaining stomach and proximal small intestine, where it is normally absorbed, reducing the amount of food and calories absorbed. The pouch is connected to the proximal jejunum; the opening between them is narrow, limiting the rate of gastric emptying. The segment of small intestine connected to the bypassed stomach is attached to the distal small intestine. This arrangement allows bile acids and pancreatic enzymes to mix with gastrointestinal contents, limiting malabsorption and nutritional deficiencies. RYGB is particularly effective in treating Diabetes Mellitus (DM) ; remission rates are up to 62% after 6 years ( Short-term complications include anastomotic leak (more commonly at the gastrojejunal connection) and bleeding. Dumping syndrome can occur after eating high-fat and high-sugar foods; symptoms can include light-headedness, diaphoresis, nausea, abdominal pain, and diarrhea. Long-term risk of ulceration at the gastrojejunal anastomosis can occur in patients who take nonsteroidal anti-inflammatory drugs (NSAIDs) or smoke cigarettes after RYGB. Bowel obstruction can occur if internal hernia or intussusception develops. An increasing number of patients are having revisional procedures to manage inadequate weight loss, weight regain, or other complications, such as development of GERD after sleeve gastrectomy. For RYGB, revision may involve shortening the gastric pouch or the duodenal segment that is attached to the stomach. The purpose is reduce absorption of calories and nutrients. Preoperative evaluation usually includes endoscopy and x-ray studies (eg, barium swallow). BPD-DS accounts for<5% of bariatric procedures done in the United States, but the annual number of procedures is increasing. It is usually reserved for patients with extreme morbid obesity (BMI > 50 kg/m2). BPD-DS can be done as one procedure or staged (first sleeve gastrectomy alone, then biliopancreatic diversion with duodenal switch after initial weight loss). About two-thirds to three-fourths of the upper small intestine is bypassed in the procedure. After sleeve gastrectomy, the duodenum is divided just distal to the pylorus, and a segment of ileum is brought up and anastomosed to the proximal duodenum, creating an approximately 200-cm alimentary limb that bypasses much of the small intestine and the sphincter of Oddi (where bile acids and pancreatic enzymes enter). As a result, food absorption is decreased. The other cut end of the duodenum is tied off, and a second anastomosis is made between the remainder of the excluded loop and the ileum, creating a 100-cm channel for biliary and pancreatic enzymes to enter the distal small intestine and facilitate digestion. BPD-DS is technically more difficult than sleeve gastrectomy or RYGB, but it is the most effective procedure for weight loss and resolution of type 2 diabetes. Complication rates are slightly higher than with other procedures, and malabsorption, steatorrhea, and nutritional deficiencies can occur. Patients must take nutritional supplements and be monitored for deficiencies for the rest of their life. Like BPD-DS, SADI-S includes sleeve gastrectomy and division at the first portion of the duodenum. It can be performed in one or two stages. The main difference is that SADI-S features a single loop anastomosis with a longer common channel for absorption. It is a slightly simpler and faster procedure and has less risk of nutritional deficiencies than BPD-DS. But it has a greater potential to worsen or lead to new-onset Gastroesophageal Reflux Disease (GERD) reflux symptoms. Bile reflux can also occur because there is no roux limb. Newer endoscopic procedures can help treat patients who are not candidates for surgery or who prefer a less invasive, nonsurgical approach. An intragastric balloon may be used. An uninflated silicone balloon is passed into the stomach, then filled with saline. The balloon decreases gastric volume and promotes satiety. After 6 months, the balloon is removed. Patients lose weight initially, but long-term success is limited. Endoscopic sleeve gastroplasty reduces the size of the stomach by suturing it from within. Because the sutures bring folds of the stomach together, it has been called the accordion procedure. Overall complication rates are low; the most common complications include nausea, gastrointestinal bleeding, perigastric leakage, and accumulation of fluid. Sleeve gastroplasty has a lower reflux rate than endoscopic sleeve gastrectomy, and the procedure is potentially reversible. Five-year data suggest sustained weight loss; however, longer-term data are lacking ( Procedures references ). Adjustable gastric banding is rarely performed in the United States. More often, patients who have had this procedure have the bands removed and undergo sleeve gastrectomy or RYGB. For adjustable gastric banding, the band is placed around the upper part of the stomach to divide the stomach into a small upper pouch and a larger lower pouch. Typically, the band is adjusted 4 to 6 times by injecting saline into the band via a port that is placed subcutaneously. When saline is injected, the band expands, restricting the upper pouch of the stomach. As a result, the pouch can hold much less food, patients eat more slowly, and satiety occurs earlier. Saline can be removed from the band if a complication occurs or if the band is overly restrictive. Weight loss with the band varies and is related to the frequency of follow-up; more frequent follow-ups result in greater weight loss. Early postoperative morbidity and mortality rates are lower than with other procedures. Long-term complications include gastroesophageal reflux, esophagitis, slipped bands, and erosion. 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