The duodenal switch (BPD-DS), or biliopancreatic diversion with duodenal switch, is a bariatric surgical procedure designed to treat obesity and related health conditions. It combines restrictive and malabsorptive elements to achieve significant and lasting weight loss. This article provides a detailed overview of the duodenal switch procedure, including its history, how it works, what to expect before and after surgery, its effectiveness, advantages, disadvantages, and potential risks.
Introduction to Bariatric Surgery and the Duodenal Switch
Surgical interventions for obesity emerged from observations of weight loss in patients who underwent stomach or small bowel resections. One of the earliest procedures, the jejunoileal bypass developed in 1954, was eventually abandoned due to severe side effects. However, advancements in bariatric techniques and equipment, coupled with a better understanding of the procedure's impact on overall health, have led to its resurgence.
Key milestones in the acceptance of bariatric surgery include:
- The National Institutes of Health consensus conference in 1992, which endorsed vertical gastric banding as a safe and effective weight loss method.
- A 1995 study demonstrating the positive long-term effects of bariatric surgery on diabetes management.
- Improvements in bariatric equipment, leading to fewer postoperative complications.
The first laparoscopic gastric bypass surgery was performed in 1994. With increased experience and improved outcomes, laparoscopic procedures have largely replaced open surgery, resulting in fewer wound complications, incisional hernias, shorter hospital stays, and decreased mortality rates.
How the Duodenal Switch Works
The duodenal switch procedure works through a combination of restriction and malabsorption. The Biliopancreatic Diversion with Duodenal Switch, abbreviated BPD-DS, begins with creation of a tube-shaped stomach pouch similar to the sleeve gastrectomy. The smaller stomach, shaped like a banana, allows patients to eat less food. Also, part of your small intestine is rerouted so that food travels through your digestive system more quickly.
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The malabsorptive portion of the surgery reroutes a lengthy portion of the small intestine, creating two separate pathways and one common channel. The shorter of the two pathways, the digestive loop, takes food from the stomach to the common channel. The common channel is the portion of small intestine, usually 75-150 centimeters long, in which the contents of the digestive path mix with the bile from the biliopancreatic loop before emptying into the large intestine. The food stream bypasses roughly 75% of the small intestine, the most of any commonly performed approved procedures. This results in a significant decrease in the absorption of calories and nutrients.
Hormonal Impact
Bariatric procedures significantly impact hormones that regulate weight and metabolism. Important hormones that are directly impacted by bariatric surgery that have a significant impact on patients' weight loss and outcomes are leptin, incretins (GIP and GLP1), ghrelin, and insulin.
- Ghrelin: This hormone, produced in the GI tract, stimulates appetite. Bariatric procedures can affect ghrelin production, potentially reducing hunger.
- Leptin: Produced by adipose cells, leptin regulates energy balance by controlling hunger and fat storage. In obesity, decreased sensitivity to leptin can occur. Bariatric surgery, particularly Roux-en-Y gastric bypass, has been shown to decrease leptin resistance.
- Incretins (GIP and GLP-1): These hormones enhance insulin secretion, delay gastric emptying, decrease appetite, and improve insulin sensitivity. Incretin levels have been shown to increase following biliopancreatic diversion and gastric bypass.
- Insulin: This hormone regulates the metabolism of carbohydrates, fats, and protein. Decreased insulin sensitivity leads to diabetes mellitus and obesity. It has been shown that insulin sensitivity improves with all types of bariatric surgery.
Who is a Good Candidate for Duodenal Switch Surgery?
Duodenal switch surgery is typically considered for individuals who:
- Have a Body Mass Index (BMI) greater than 50 (superobese) or are morbidly obese.
- Have struggled to lose weight through diet and exercise.
- Are healthy enough to tolerate surgery.
- Have comorbid conditions, like diabetes.
What Happens Before Duodenal Switch Surgery?
If your healthcare provider believes you’re a good candidate for surgery, you’ll enter a screening process. This could involve:
- Standard medical testing to make sure you’re in good health.
- Screening for alcohol, tobacco and drug use and therapy to help you quit, if necessary.
- Psychological counseling to make sure you’re prepared for the big life changes that your new digestive system will bring.
- Enrolling in a seminar so you understand the surgery.
Once you’ve met these benchmarks and scheduled your surgery, your healthcare provider will put you on a preoperative eating plan for a couple of weeks. This typically consists of eating meals that are low in fat and carbohydrates and high in protein. Patients are typically placed on a Low carbohydrate diet before surgery to shrink the liver as much a possible before surgery. Studies have shown that preoperative weight loss may lead to some improvements in postoperative outcomes and possibly decrease complications.
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Multidisciplinary Team Evaluation
Bariatric surgery typically requires a multidisciplinary team that evaluates the patient before surgery. This includes a dietitian, a psychiatric specialist, an anesthetist, nursing, surgical team, and the primary care provider.
- Psychological Evaluation: Patients must be psychologically fit to undergo bariatric surgery. This will help avoid major postoperative complications. Patients need to be evaluated for psychological disorders such as depression, anxiety, and eating disorders. It is necessary to evaluate the patient's support system that they have available. They should be evaluated for substance misuse disorders, such as alcohol or drug use. If they have alcohol dependence, they will need rehabilitation before planning the procedure. If the patient is smoking, smoking cessation needs to be encouraged before proceeding with the operation.
- Nutritional Evaluation: The nutritional evaluation includes assessment and education that will direct the patient toward dietary changes needed after surgery.
- Medical Evaluation: As with all surgeries, medical evaluation and clearance are extremely important in the preoperative period. Patients must have a detailed history and physical, a thorough review of their prior surgeries, and past medical history. Recent laboratory studies should be performed. Patients' functional status must be determined, and if there is a concern, further workup may be warranted by a cardiologist. Patients who have obstructive sleep apnea need to be evaluated with a sleep study and pulmonologist before surgery.
Currently, there is no consensus regarding the imaging modalities to be obtained before a bariatric procedure. Several studies have evaluated the use of abdominal ultrasounds to evaluate liver pathology, size, and cholelithiasis. EGD before bariatric surgery remains a controversial topic. Some recommend a preoperative evaluation with EGD before restrictive procedures such as sleeve gastrectomy or adjustable gastric banding. These restrictive procedures may place these patients at a greater risk of worsening gastroesophageal reflux and Barrett's esophagus.
Preoperative Preparation
Patients are placed under general anesthesia. Intravenous preoperative antibiotics and thromboprophylaxis are given prior to the start of the procedure. Patients are placed in the supine position with split legs position. Both arms are out to the side. The patient will be secured with straps and tape in order to prevent patient movement with table positioning. Sequential compression devices will be placed on the patient's legs. A 15-cm Veress needle is introduced at palmers point (left subcostal area) to create a 15-mm HG pneumoperitoneum. A 5- or 10-mm optical trocar is placed under direct vision 2 fingerbreadths below the xiphoid process for the camera. A 12-mm port is placed at the left and right flanks. A 5-mm port is placed at the epigastrium for the liver retractor.
How is a Duodenal Switch Done?
Duodenal switch surgery is a laparoscopic surgery. The laparoscopic method is less invasive and uses small incisions instead of making a larger incision in your abdomen. You receive general anesthesia so you’re asleep for the entire procedure.
There are two surgical methods to the duodenal switch: the traditional duodenal switch (biliopancreatic diversion) and the SADI-S. The Biliopancreatic Diversion with Duodenal Switch, abbreviated BPD-DS, begins with creation of a tube-shaped stomach pouch similar to the sleeve gastrectomy. In a duodenal switch operation, a surgeon will remove about 70 to 80% of your stomach, leaving a tube-like pouch. The smaller stomach, shaped like a banana, allows patients to eat less food. Also, part of your small intestine is rerouted so that food travels through your digestive system more quickly.
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The first step in both methods involves removing part of your stomach and shaping what’s left of it into a narrow sleeve. Dissection is begun by opening the gastrocolic ligament at the level of the gastric body. This is done using an ultrasonic scalpel. The greater curvature of the stomach is then mobilized from the antrum to the angle of His. In super obese patients who have short mesentery and adhesions, sleeve gastrectomy may be performed as a first-stage operation. The pylorus is then identified and dissected free. The peritoneum is opened at the inferior and superior edges of the duodenum. The patient's antrum will be pulled to the left to visualize the duodenum better. The common bile duct will be identified on the superior aspect of the duodenum. This can be used as a landmark for further dissection. The duodenum can then be mobilized by the inferior or posterior approach. For the inferior approach, the gastrocolic ligament is divided using the harmonic. The pyloric artery is controlled. A posterior dissection is continued for the first 3 to 4 cm of the duodenum. The gastroduodenal artery is a marker for the limit of the posterior dissection. The duodenum will be divided using a 60-mm linear stapler at this point.
In the posterior approach, a window is created 3 to 4 cm distal to the pylorus. Blunt dissection is performed to find the plane between the duodenal wall and the pancreas. Careful dissection is required to avoid small venous branches to the pancreatic head from the gastroduodenal artery. Gastric transsection is started from 5 to 7 cm from the pylorus. A linear stapler with 60-mm loads is used. The gastric transfection proceeds towards the fundus. A 32 to 40 French esophagogastric bougie is usually placed for guidance. Hemostasis on the staple line is controlled using clips or a 3-0 absorbable suture.
The differences are in the second part of the surgery - the intestinal bypass. Both versions begin the bypass by dividing your small intestine near the top, in the section called the duodenum. Then, they bring a lower section of your small intestine up to attach to the top, bypassing the middle. The patient is placed in the Trendelenburg position with the left side down. The ileocecal junction is identified, and any intrabdominal adhesions between the ascending colon and greater omentum are divided. The length of the metallic part of the laparoscopic bowel graspers (5 cm) is used to measure the alimentary limb. The small bowel is measured 100 cm from the ileocecal junction. Then, the small bowel is run another 150 cm and transected at that level using a 60-mm linear stapler. The alimentary limb is brought to the right upper quadrant in an ante colic fashion and brought to the transected portion of the duodenum. The omentum is mobilized from the ascending colon to relieve tension on the anastomosis. A hand-sewn or stapled end-to-side anastomosis is created. The anastomosis can be tested by insufflating air through the nasogastric tube. The ileoileal anastomosis is then created at 100 cm from the ileocecal valve. Following the completion of the anastomosis, the mesenteric window (Petersen window) is closed to prevent an internal hernia.
The original duodenal switch surgery bypasses most of your small intestine, making it significantly shorter. The modified version bypasses a little more than half of your small intestine. The surgery typically takes between two and four hours.
What Happens After Duodenal Switch Surgery?
You’ll stay in the hospital for one to two days after surgery. It takes two to four weeks to make a full recovery. Your healthcare provider will give you instructions to follow during your recovery. This will include a list of what activities to avoid and what foods you can eat.
You’ll have frequent follow-up appointments with your healthcare provider in the first two years and periodic appointments for the rest of your life. The first two years will be your most dramatic weight-loss period. During this time, your provider will continuously monitor your progress and health.
Dietary Progression
For the first few weeks after surgery, you will need to follow a carefully monitored diet, starting with a liquid diet and slowly reintroducing specific types of food. Initially, you will feel full very quickly after eating a small amount of food. After surgery, the stomach is roughly the size and shape of a banana and can hold approximately 3 ounces of food, as compared to the average stomach which can hold up to 4 cups of volume. It is important that patients who have had a duodenal switch procedure make a lifelong commitment to making the necessary changes in their diet.
Lifelong Supplementation
Because there’s a risk of malnutrition, you’ll need to take nutritional supplements for the rest of your life. You’ll also need to give blood samples at regular intervals to make sure you’re getting enough nutrients. Patients must take vitamins and mineral supplements after surgery. The malabsorptive element of the DS requires that those who undergo the procedure take vitamin and mineral supplements in excess of those needed by the normal population, as do patients having the RNY surgery. Like RNY patients, DS patients require lifelong and extensive blood tests to check for deficiencies in life-critical vitamins and minerals. Without proper follow up tests and lifetime supplementation RNY and DS patients can become ill.
Advantages of the Duodenal Switch
Duodenal switch helps you lose weight and reduces your risk of serious obesity-related health problems. It can significantly improve your quality of life but requires that you make changes to your lifestyle. Some more specific advantages are:
- Greatest overall weight loss results
- Most effective weight-loss procedure for people with Type 2 diabetes
- Allows for slightly larger meals when compared to other gastric bypass procedures
- Rarely causes dumping syndrome
- Type 2 diabetics have had a 98% "cure" almost immediately following surgery, which is due to the metabolic effect from the intestine switch.
Disadvantages and Risks of the Duodenal Switch
One of the main disadvantages of the surgery is that it relies on malabsorption, which can help you lose weight. But it also requires you to follow a specific eating plan and take specific supplements to get the nutrition you need. You need to follow the eating plan to avoid loose bowel movements, as well.
Like any surgery, a duodenal switch carries some risk for complications; the risk for these complications are increased for obese patients.
The incidence of a gastric or duodenal leak following biliopancreatic diversion with duodenal switch is 1.14% vs. 1.12% for Roux en-Y gastric bypass. The leak site appears to be more common at the duodenoduodenal anastomosis. The risk of leakage from the longitudinal gastric staple line is minimal compared to the leak rate from the gastric staple line in the gastric bypass procedure. These patients may be asymptomatic, but they frequently present with tachycardia, which is usually the first sign. They can also have tachypnea and be febrile.
Other risks may include:
- Gastroesophageal Reflux (GERD) - Because the procedure reduces the size of the stomach, it may also increase pressure on the esophagus.
- Protein, vitamin and mineral deficiencies.
- Gallstones are a common complication of rapid weight loss following any type of weight loss surgery, some surgeons may remove the gall bladder as a preventative measure during the DS or the RNY.
- Longer term risks include the possibility of vitamin and mineral deficiency, hernia and bowel obstruction.
- The traditional biliopancreatic diversion with duodenal switch (BPD-DS) led to persistent malnutrition in some patients.
- Duodenal switch surgery is not reversible.
How Effective is the Duodenal Switch?
Duodenal switch surgery is one of the most successful bariatric surgeries. It results in a higher BMI loss (decreasing your BMI) when compared to gastric bypass. Patients can expect to lose 80 to 90 percent of excess weight in the first year after a duodenal switch operation. By losing excess weight, other illnesses associated with obesity can greatly improve.
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