Malabsorptive Surgeries: Surgical Techniques, Results, and Challenges

Malabsorptive Surgery: Surgical Techniques, Results, and Challenges describes the development of classic and new malabsorptive surgical techniques. Coverage includes the results obtained after the procedures, as well as postoperative complications - including early complications (associated with the difficulty of the operation) and late complications (associated with nutritional sequelae). This book is the perfect reference for basic and translational research focused on the mechanism of action of malabsorptive procedures, that goes beyond the bypassing of intestinal loops, affecting the regulation of hormonal signals. The content is also useful for bariatric surgeons and endocrinologists dealing with the bariatric options and results. Despite the aims of bariatric surgery focusing on performing procedures associated with low postoperative complications rates (mostly restrictive procedures), there is increasing evidence showing mid- and long-term failure of restrictive and mixed procedures in terms of weight regain and recurrence of comorbidities. This has increased the need for revisional surgeries after failed primary procedures, and consequently, increased the popularity of malabsorptive techniques.

• Introduces new malabsorptive techniques, including OAGB and SADIS, which have improved results and reduced the nutritional sequalae of more classic approaches like biliopancreatic diversion and duodenal switch
• Provides insights into basic and translational research focused on the mechanism of action of malabsorptive procedures that goes beyond the bypassing of intestinal loops, thus affecting the regulation of hormonal signals
• Presents step-by-step procedures with accompanying images to guide performance of specific procedures

• Language: English
• Publisher: Academic Press
• Release date: Jun 7, 2024
• ISBN: 9780443216732

Book preview

Section 1

Preoperative evaluation

Outline

Chapter 1. Types of bariatric procedures and their fundaments

Chapter 2. Selection of patients for malabsorptive surgery: Indications and contraindications

Chapter 3. Psychological assessment of candidates for a malabsorptive surgery

Chapter 4. Special anesthetic considerations for patients planned for a malabsorptive surgery

Chapter 5. Nutritional optimization prior to malabsorptive surgery

Chapter 1: Types of bariatric procedures and their fundaments

Adriana Avilés Oliveros¹, Jaime Ruiz-Tovar²,³, Manuel Medina Pedrique¹, Sara Morejón Ruiz¹, and Arturo Cruz Cidoncha¹     ¹Department of General Surgery, University Hospital of Henares, Coslada, Madrid, Spain     ²San Juan de Dios Foundation, Madrid, Spain     ³Comillas Pontifical University, Health Sciences Department, San Juan de Dios School of Nursing and Physical Therapy, Madrid, Spain

Abstract

Obesity is a prevalent chronic medical condition affecting around 13% of the world's adult population, and it is linked to various comorbidities. Bariatric surgery remains the most effective and sustainable treatment option for severe obesity. Bariatric procedures can be categorized into restrictive, malabsorptive, and mixed types. This chapter discusses the different types of bariatric procedures, including Roux-en-Y gastric bypass, sleeve gastrectomy, adjustable gastric banding, biliopancreatic diversion with duodenal switch, one-anastomosis gastric bypass, and single-anastomosis duodenoileal bypass with sleeve gastrectomy. Restrictive procedures limit food intake, while malabsorptive procedures aim to reduce calorie and nutrient absorption by rerouting or bypassing a portion of the small intestine. Mixed procedures combine both restrictive and malabsorptive mechanisms to achieve weight loss.

Keywords

Adjustable gastric banding; Bariatric surgery; Duodenoileal bypass; Obesity; Roux-en-Y gastric bypass; Sleeve gastrectomy

Introduction

According to the WHO, obesity is a chronic medical condition that affects approximately 13% of the world's adult population. It is a complex disease associated with a multitude of comorbidities, including type 2 diabetes, hypertension, cardiovascular diseases, and sleep apnea, among others. Despite several nonsurgical interventions for weight loss, bariatric surgery remains the most effective and sustainable option for patients with severe obesity.

Bariatric procedures are a group of surgical techniques used to control severe obesity and its related comorbidities. These procedures can be broadly classified into three categories: restrictive, malabsorptive, and mixed. In this chapter, we will discuss the different types of bariatric procedures and their fundamentals, including the Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy, adjustable gastric banding (AGB), biliopancreatic diversion with duodenal switch (BPD-DS), one-anastomosis gastric bypass (OAGB), and single-anastomosis duodenoileal bypass with sleeve gastrectomy (SADI-S).

Restrictive procedures limit the amount of food a patient can eat by reducing the size of the stomach or by creating a small pouch in the upper part of the stomach. The most common restrictive procedures are sleeve gastrectomy and AGB.

Malabsorptive procedures in bariatric surgery aim to reduce the absorption of calories and nutrients by rerouting or bypassing a portion of the small intestine. These procedures have been shown to produce significant and sustained weight loss, particularly in patients with a high BMI or significant comorbidities, such as type 2 diabetes, hypertension, and sleep apnea.

The two most common malabsorptive procedures are the BPD and the BPD/DS.

The BPD procedure involves removing a portion of the stomach and rerouting the small intestine to create a Y-shaped configuration. The duodenum and a portion of the jejunum are bypassed, which reduces the absorption of calories and nutrients. The remaining portion of the stomach is connected to the small intestine, allowing for some degree of restriction.

The BPD/DS procedure is a modification of the BPD procedure and combines both restrictive and malabsorptive techniques. A smaller stomach pouch is created similar to the sleeve gastrectomy, and a portion of the small intestine is rerouted to bypass the majority of the stomach and duodenum. The remaining small intestine is connected to the duodenum to allow for some degree of absorption.

Mixed procedures combine restrictive and malabsorptive mechanisms to achieve weight loss. The most common mixed procedure is the RYGB, which involves creating a small stomach pouch and bypassing the small intestine to the pouch. This procedure limits food intake and reduces the absorption of calories and nutrients. Another mixed procedure is the sleeve gastrectomy with duodenal switch, which involves combining sleeve gastrectomy with the duodenal switch to achieve both restrictive and malabsorptive effects.

Restrictive procedures

The main effect of restrictive techniques is the reduction of the total volume of food ingested. They decrease the effective gastric volume by creating a small gastric reservoir (30–50 mL) with a narrow outlet. When this small reservoir is filled with food, an early sensation of satiety and fullness is obtained, which slows down food intake or may even cause vomiting if food intake continues. The reservoir can be created by placing a ring near the cardia (gastric band), sectioning the stomach at the angle of His and placing a ring as a neopilorus (vertical banded gastroplasty), or by resecting the greater gastric curvature, leaving a narrow tube at the expense of the lesser curvature (vertical gastrectomy).

In recent years, the sleeve gastrectomy has emerged as the leading restrictive weight loss procedure. Its effectiveness is likely attributed to its impact on hunger control hormones. While other methods, such as intragastric balloon placement or aspiration therapy, also limit food intake, they tend to result in slower and more modest weight loss, and are associated with higher rates of weight regain compared to other modern surgical approaches.

Sleeve gastrectomy

Sleeve gastrectomy is currently the most popular bariatric procedure worldwide, accounting for approximately 38% of all bariatric surgeries. It is a partial gastrectomy in which the majority of the greater curvature of the stomach is removed and a tubular stomach is created. Sleeve gastrectomy works by restricting the amount of food a patient can eat and reducing hunger by removing the portion of the stomach that produces the hormone ghrelin, which is responsible for stimulating appetite. The procedure also has metabolic effects, including improvements in glucose control and insulin sensitivity, which can benefit patients with type 2 diabetes. Moreover, the hormonal changes it causes indicate that its success is not only due to restricted food intake. Ghrelin levels decrease and GLP-1 and PYY levels increase, promoting less hunger, while insulin resistance improves and aids glycemic control. The fundamental principle of sleeve gastrectomy is restriction, and it does not involve rerouting or bypassing the small intestine.

The SG is technically easier to perform and viewed as not as drastic by patients. It is also safer as it reduces the risks of internal herniation and protein and mineral malabsorption. The procedure is usually performed laparoscopically. The surgeon removes a large portion of the stomach, leaving a thin vertical sleeve-shaped tube. The new stomach pouch can hold approximately 100–120cc of food, compared to the normal stomach, which can hold up to 1500 mL of food.

Sleeve gastrectomy is generally considered safe and effective, with a low risk of complications compared to other bariatric procedures. However, like all surgeries, sleeve gastrectomy carries risks, such as bleeding, infection, and blood clots. There is also a risk of developing nutritional deficiencies, such as vitamin B12 and iron deficiency, as the body absorbs fewer nutrients due to the smaller stomach size.

Sleeve gastrectomy is a good option for patients with a BMI of 40 or higher or a BMI of 35 or higher with obesity-related comorbidities, such as diabetes, high blood pressure, or sleep apnea. The procedure may also be suitable for patients who cannot tolerate other bariatric procedures due to their health status.

The average weight loss after sleeve gastrectomy is around 60%–70% of excess body weight, and the procedure has been shown to improve or resolve many obesity-related comorbidities.

Adjustable gastric banding

AGB, also known as laparoscopic gastric banding, is a bariatric procedure that involves placing an inflatable silicone band around the upper part of the stomach. The band creates a small pouch that can hold only a limited amount of food, which makes the patient feel full faster and eat less. The procedure is a purely restrictive technique and does not involve the rerouting or bypassing of the small intestine.

The procedure is typically performed laparoscopically, using several small incisions in the abdomen. The surgeon places the adjustable silicone band around the upper part of the stomach and secures it in place with sutures. The band is then connected to an access port placed under the skin of the abdomen, which allows the surgeon to inflate or deflate the band as needed to adjust the size of the pouch and control the rate of weight loss.

AGB is a reversible procedure, as the band can be removed if necessary. It also carries a lower risk of complications compared to other bariatric procedures. However, patients must follow strict dietary guidelines and attend regular follow-up appointments to ensure the success of the procedure.

The procedure has a lower risk of complications compared to other bariatric procedures. However, patients must follow strict dietary guidelines and attend regular follow-up appointments to ensure the success of the procedure.

AGB is generally recommended for patients with a BMI between 30 and 40 who have not been successful with diet and exercise alone. The procedure may also be suitable for patients who are not good candidates for more invasive bariatric surgeries.

In conclusion, AGB is a safe and effective bariatric procedure that creates a small pouch in the upper part of the stomach to restrict the amount of food a patient can eat. The procedure is minimally invasive and reversible, with a lower risk of complications compared to other bariatric surgeries. However, patients must commit to strict dietary guidelines and regular follow-up appointments to ensure the success of the procedure.

Malabsorptive procedures

Malabsorptive procedures decrease the effectiveness of nutrient absorption by shortening the absorption length of the functional small intestine, either through bypass of the small bowel absorptive surface area or diversion of the biliopancreatic secretions that facilitate absorption. The classic malabsorptive procedures are the BPD and the BPD-DS. Scopinaro described the BPD as a diversion of the bile and pancreatic juice (via the biliopancreatic limb) from food (in the alimentary limb), combined with a subtotal gastrectomy. The BPD-DS was described by Marceau and features a sleeve gastrectomy with pyloric preservation and reconstruction, plus an ileoduodenostomy. The degree of malabsorption for BPD/BPD-DS varies according to the length of the common channel (50–125 cm), in which the digestion and absorption occur. The shorter the common channel, the more effective the weight loss. However, side effects such as diarrhea and severe vitamin A and D deficiencies also increase as the length of the common channel decreases. Sufficient gastric volume, ideally including the pylorus (which allows for a dosed release of food into the small bowel), and a sufficient alimentary limb length (>200 cm) are crucial for protein malnutrition prevention.

Biliopancreatic diversion with duodenal switch

BPD/DS is a complex weight loss surgery that combines both restrictive and malabsorptive approaches to achieve significant and sustained weight loss. The procedure is primarily used for individuals with a BMI greater than 50 or those with a BMI greater than 40 with significant comorbidities, such as type 2 diabetes, hypertension, and sleep apnea.

The BPD/DS procedure involves two major steps. The first step is to create a smaller stomach pouch, similar to sleeve gastrectomy. This is done by removing a portion of the stomach, leaving behind a smaller pouch that can hold only a limited amount of food. This restricts the amount of food that can be consumed at one time, leading to a feeling of fullness and satiety with smaller meals.

The second step of the BPD/DS procedure involves rerouting a portion of the small intestine. This creates two separate pathways for food to pass through. The first pathway allows food to mix with digestive enzymes and bile from the liver and pancreas, similar to normal digestion. The second pathway bypasses the majority of the small intestine and carries only digestive juices. This rerouting of the intestines leads to malabsorption of nutrients, resulting in additional weight loss.

BPD/DS has been shown to produce significant weight loss, with patients losing up to 60%–70% of their excess weight within the first 2 years after surgery. The procedure has also been shown to improve or resolve comorbidities such as type 2 diabetes, hypertension, and sleep apnea.

However, BPD/DS is not without its risks and potential complications. The procedure is associated with a higher risk of nutritional deficiencies, particularly in fat-soluble vitamins and minerals such as calcium, vitamin D, and iron. Patients must take lifelong vitamin and mineral supplements and undergo regular blood tests to monitor their nutritional status.

Other potential complications of BPD/DS include infections, bleeding, and bowel obstructions. The procedure also carries a higher risk of complications in patients with a high BMI or those with significant comorbidities.

To ensure the success and safety of the procedure, patients must adhere to strict dietary and nutritional guidelines. This includes consuming a high-protein, low-carbohydrate diet, avoiding sugary and fatty foods, and taking vitamin and mineral supplements as prescribed by their healthcare provider. Patients must also undergo regular monitoring, including blood tests and nutritional assessments, to ensure that they are meeting their nutritional needs and that the procedure is working effectively.

In conclusion, BPD/DS is a highly effective weight loss surgery for individuals with a high BMI or significant comorbidities. The procedure combines both a restrictive and malabsorptive approach to achieve significant and sustained weight loss. However, the procedure is associated with a higher risk of nutritional deficiencies and potential complications, and patients must adhere to strict dietary and nutritional guidelines and undergo regular monitoring to ensure the success and safety of the procedure.

Mixed procedures

The RYGB, the BPD/DS, and the SADI-S are established weight loss procedures that incorporate both restrictive and malabsorptive elements. While RYGB restricts oral intake through a small gastric pouch, the reconfiguration of the small bowel contributes to additional mechanisms that facilitate weight loss, such as dumping physiology, positive hormonal changes, and mild malabsorption. These procedures also impact hunger control through hormonal changes.

In addition to these commonly used procedures, there are less common options like the OAGB and the single-anastomosis duodenal ileal bypass (SADI) that also utilize restrictive and malabsorptive elements, as well as hormonal modulation, to promote weight loss.

Mixed procedures have been shown to produce significant and sustained weight loss, with patients losing up to 60%–70% of their excess weight within the first 2 years after surgery. These procedures have also been shown to improve or resolve comorbidities such as type 2 diabetes, hypertension, and sleep apnea.

However, mixed procedures are more complex and carry a higher risk of potential complications, including nutritional deficiencies, infections, bleeding, and bowel obstructions. Patients must adhere to strict dietary and nutritional guidelines and undergo regular monitoring to ensure that they are meeting their nutritional needs and that the procedure is working effectively.

Roux-en-Y gastric bypass

RYGB is a type of bariatric surgery that involves creating a small stomach pouch and rerouting the small intestine to connect to the pouch. The procedure combines both restrictive and malabsorptive techniques, as the small stomach pouch limits the amount of food a patient can eat, and the rerouting of the small intestine reduces the amount of calories and nutrients absorbed.

The surgery is performed laparoscopically, using several small incisions in the abdomen. The surgeon divides the stomach into two parts, creating a small pouch at the top that can hold only a limited amount of food. The small intestine is then divided and rerouted to connect to the pouch, bypassing the remaining larger part of the stomach and the upper portion of the small intestine. The new connection allows food to bypass the duodenum, where most of the calories and nutrients are absorbed, leading to malabsorption.

RYGB has been shown to produce significant weight loss and improve obesity-related conditions such as type 2 diabetes, hypertension, and sleep apnea. The procedure also reduces the production of ghrelin, a hormone that stimulates appetite, leading to a decrease in hunger and increased satiety.

The procedure has a higher risk of complications compared to purely restrictive techniques such as gastric banding. Complications may include dumping syndrome, where food moves too quickly through the stomach and small intestine, leading to nausea, vomiting, and diarrhea. The rerouting of the small intestine can also lead to nutritional deficiencies, particularly in vitamins and minerals such as iron, calcium, and vitamin B12. Patients must take vitamin and mineral supplements for life and attend regular follow-up appointments to monitor their nutritional status.

RYGB is generally recommended for patients with a BMI of 40 or higher, or a BMI of 35 or higher with obesity-related conditions such as type 2 diabetes, hypertension, or sleep apnea. The procedure may also be suitable for patients who have not been successful with other weight loss methods.

In conclusion, RYGB is a bariatric procedure that combines both restrictive and malabsorptive techniques to achieve significant weight loss and improve obesity-related conditions. The procedure involves creating a small stomach pouch and rerouting the small intestine to bypass the duodenum. However, the procedure carries a higher risk of complications and requires strict dietary and nutritional guidelines to ensure the success and safety of the procedure.

One-anastomosis gastric bypass

The OAGB, also known as the mini-gastric bypass, is a modified version of the loop gastric bypass. Compared to the RYGB, the OAGB is easier to perform as it only requires one anastomosis. It is a relatively simple and safe procedure that can be revised, converted, or reversed if necessary.

The OAGB is usually performed laparoscopically, involving the division of the stomach between the antrum and body on the lesser curvature. The stomach is further divided in the cephalad direction to the angle of His, creating a pouch that is then anastomosed to a loop of jejunum. This creates a restrictive and malabsorptive component for weight loss. While there is no standardized length for the biliopancreatic limb, most studies have used a 200 cm length distal to the ligament of Treitz.

Although not extensively studied, there are likely hormonal changes that occur with the OAGB that improve insulin sensitivity and reduce hunger. Overall, the OAGB offers an effective weight loss solution for patients, combining both restrictive and malabsorptive elements. However, as with any surgical procedure, there are potential risks and complications that should be discussed with a medical professional prior to undergoing the surgery.

Single-anastomosis duodenoileal bypass with sleeve gastrectomy

SADI-S is a variant of the BPD/DS, where the transected duodenum is anastomosed to a loop of distal small bowel. This differs from the classic BPD/DS, which uses a Roux-en-Y configuration with two anastomoses. The purpose of SADI-S is to reduce the complexity and associated risks of the Roux-en-Y configuration with small-diameter distal bowel.

SADI-S can also be used as a conversional procedure for inadequate weight loss after either RYGB or SG. The sleeve is created first, followed by the division of the duodenum about 4 cm from the pylorus. A single anastomosis is then created between the side of the distal small bowel and the end of the sleeve-like gastric pouch/duodenum.

Most contemporary publications on SADI-S use a common channel length of no less than 300 cm, but SG sizes may vary widely. Weight loss occurs through restrictive, malabsorptive, and hormonal mechanisms. SADI-S is a viable option for patients seeking a bariatric procedure, but as with any surgery, it comes with potential risks and complications.

Further reading

[1]. 43 Cirugía bariátrica, . In Cirugía AEC: Manual de la Asociación Española de Cirujanos. Madrid: Editorial Médica Panamericana; 2022.

[2]. Lim R.B. Bariatric procedures for the management of severeobesity: Descriptions. UpToDate; 2023. https://www.uptodate.com/contents/bariatric-procedures-for-the-management-of-severe-obesity-descriptions.

[3]. Billeter A.T, Fischer L, Wekerle A.-L, Senft J, Müller-Stich B. Malabsorption as a Therapeutic approach in bariatric surgery. Visc Med. 2014;30(3):198–204. doi: 10.1159/000363480.

[4]. Scopinaro N, Adami G.F, Marinari G.M, Gianetta E, Traverso E, et al. Biliopancreatic diversion. World J Surg. 1998;22(9):936–946. doi: 10.1007/s002689900497.

Chapter 2: Selection of patients for malabsorptive surgery: Indications and contraindications

Manuel Medina Pedrique¹, Adriana Avilés Oliveros¹, Sara Morejón Ruiz¹, Alvaro Robin Valle de Lersundi¹, Victor Vaello Jodra¹, and Jaime Ruiz-Tovar²,³     ¹Department of General Surgery, University Hospital of Henares, Coslada, Madrid, Spain     ²San Juan de Dios Foundation, Madrid, Spain     ³Comillas Pontifical University, Health Sciences Department, San Juan de Dios School of Nursing and Physical Therapy, Madrid, Spain

Abstract

Malabsorptive bariatric surgery is a type of weight loss surgery that involves reducing the absorption of nutrients by the small intestine. Patient selection is a crucial step in ensuring the success of this procedure. A thorough evaluation of the patient's medical history, physical examination, and laboratory tests is necessary to identify patients who are suitable candidates for this procedure. The ideal candidates are typically those who have a body mass index (BMI) of over 40 or a BMI of 35–39.9 with significant comorbidities such as type 2 diabetes or hypertension. Patients with a history of psychiatric disorders, substance abuse, or previous bariatric surgery may require special consideration. Patient education and counseling are also essential to ensure that patients understand the risks and benefits of the procedure and are committed to making the necessary lifestyle changes. Ultimately, careful patient selection is critical to achieving successful outcomes in malabsorptive bariatric