Prof. Dr. R. K .Mishra INTRODUCTION Obesity has become a major health problem in the last few decades. Obesity is the most prevalent chronic disease of the 21st century. The World Health Organization (WHO) has identified obesity as one of the five leading health risks in developed countries. WHO has reported that over a billion people are overweight and that 300 million are clinically obese with a projection of 3 million deaths annually worldwide. In the United States, 65% of adult Americans are overweight and 31% are clinically obese. Fourteen percent of American children and adolescents are obese. Bariatric surgery is now considered the only valid therapeutic option for morbidly obese patients but can be associated with significant risk, especially in patients affected by lifethreatening comorbidities. Morbid obesity [defined as a body mass index (BMI) > 40 kg/m2] affects 4.7% of Americans and these numbers are rapidly rising. For these patients, surgery represents the most effective treatment. However, failure is frequent issue and selection of correct surgery is of paramount importance for success. Among various bariatric procedures, laparoscopic sleeve gastrectomy (LSG) has rapidly gained popularity to become most frequently performed worldwide. The sleeve gastrectomy is a restrictive form of weight loss surgery in which approximately 85% of the stomach is removed leaving a cylindrical or sleeve-shaped stomach with a capacity ranging from about 60 to 150 cc. Stomach is reduced to about 15% of its original size, by surgical removal of a large portion of the stomach along greater curvature (Fig. 1). The open edges are then attached together with the help of stapler to form a sleeve or tube with a banana shape (Figs. 2A and B). The procedure permanently reduces the size of the stomach. The procedure is performed either open or laparoscopically and is not reversible. Laparoscopic sleeve gastrectomy is a relatively new option originally published by Marceau et al. Unlike many other forms of bariatric surgery, the outlet valve and the nerves to the stomach remain intact and, while the stomach is drastically reduced in size, although its function is preserved. Again, unlike other forms of surgery such as the Roux-en-Y gastric bypass (RYGB), the sleeve gastrectomy is not reversible. Fig. 1: Sleeve gastrectomy. Because the new stomach continues to function normally there are far fewer restrictions on the foods which patients can consume after surgery, although the quantity of food that can be eaten will be considerably reduced. This is seen by many patients as being one of the great advantages of the sleeve gastrectomy, as is the fact that the removal of the majority of the stomach also results in the virtual elimination of hormone (ghrelin) produced within the stomach which stimulate hunger. GHRELIN HORMONE Ghrelin got its name from the word “ghre” from the ProtoIndo-European language, meaning to grow. Scientists did not go purposefully looking for a substance that stimulated appetite. Indeed the discovery of ghrelin occurred when scientists were investigating drugs that stimulated the release of growth hormone from the anterior pituitary gland. They came across some drugs that, rather than acting on the growth hormone releasing hormone receptor, were acting on an unknown receptor located in the hypothalamus and pituitary, these drugs were called growth hormone secretagogues. It was concluded that the body had a second pathway for the induction of growth hormone secretion. Ghrelin was identified as being the natural legend for these receptors causing secretion of growth hormone in
SECTION 2: Laparoscopic General Surgical Procedures 1999 by the Japanese scientist Masayasu Kojima. During Kojima’s investigations, they found that although ghrelin’s receptors were in the brain, ghrelin was surprisingly identified in the human stomach and circulating in the blood leading to the conclusion that it was released from the stomach, from where it then traveled in the blood and acted on the brain. Ghrelin is a hormone produced mainly by P/D1 cells lining the fundus of the human stomach and epsilon cells of the pancreas that stimulates hunger (Figs. 2A and B). Ghrelin levels increase before meals and decrease after meals. It is considered as the counterpart of the hormone leptin, produced by adipose tissue, which induces satiation when present at higher levels. In some bariatric procedures, the level of ghrelin is reduced in patients, thus causing satiation before it would normally occur. Ghrelin is also produced in the hypothalamic arcuate nucleus, where it stimulates the secretion of growth hormone from the anterior pituitary gland. Receptors for ghrelin are expressed by neurons in the arcuate nucleus and the ventromedial hypothalamus. Once the high amount of ghrelin is secreted the patient feels intense hunger (Fig. 3). Apart from hunger, A B Figs. 2A and B: (A) Ghrelin hormone; and (B) Role of ghrelin in glucose and lipid metabolism. (BAT: brown adipose tissue; GI: gastrointestinal; WAT: white adipose tissue)
end and slows gastric emptying and intestinal motility on the other. GLP-1 is increased after LSG, and it is postulated that increased levels of GLP-1 contribute to weight loss by improving glucose metabolism, reducing hunger, and increasing satiety. Although GLP-1 has been shown to slow gastric emptying, the gastric emptying time accelerated after LSG (47.6 ± 23.2 vs. 94.3 ± 15.4 minutes) in one study. It is likely that more than one mechanism is in play when determining the gastric transit time after LSG. LSG has also been shown to alter the levels of glucose-dependent insulinotropic peptide (GIP), bile acids, and leptin, the clinical significance of which is still under investigation. INDICATIONS OF SLEEVE GASTRECTOMY Fig. 3: Mode of action of ghrelin. ghrelin plays a significant role in neurotrophy, particularly in the hippocampus, and is essential for cognitive adaptation to changing environments and the process of learning. Ghrelin has emerged as the first circulating hunger hormone. Ghrelin and synthetic ghrelin mimetic increase food intake and increase fat mass by an action exerted at the level of the hypothalamus. They activate cells in the arcuate nucleus that include the orexigenic neuropeptide Y (NPY) neurons. Ghrelin-responsiveness of these neurons is both leptin- and insulin-sensitive. Ghrelin also activates the mesolimbic cholinergic-dopaminergic reward link, a circuit that communicates the hedonic and reinforcing aspects of natural rewards, such as food, as well as of addictive drugs, such as ethanol (Fig. 3). Ghrelin levels in the plasma of obese individuals are lower than those in leaner individuals. Recently, Scripps research scientists have developed an anti-obesity vaccine, which is directed against the hormone ghrelin. The vaccine uses the immune system, specifically antibodies, to bind to selected targets, directing the body's own immune response against them. This prevents ghrelin from reaching the central nervous system, thus producing a desired reduction in weight gain. Obesity is the result of multifactorial changes involving both genetic and environmental factors. The physiopathology of obesity from the point of view of intake regulation has led to numerous experimental studies aimed at identifying new forms of regulation. These new forms of regulation are not only found in the secretion of ghrelin from gastrointestinal system but also in the adipose tissue (via the metabolism of leptin and insulin) and the central nervous system to finally produce the relevant orexigenic or anorexigenic effect. GLUCAGON-LIKE PEPTIDE Glucagon-like peptide 1 (GLP-1) is a 30-amino-acid peptide mainly secreted by the small intestine L cells after contact of food. This hormone increases insulin secretion on one Similar to other bariatric operations, LSG is indicated in all patients meeting the 1991 National Institutes of Health (NIH) consensus conference criteria. These criteria include: ■ Body mass index ≥40 kg/m 2 with or without any associated comorbidities. ■ Body mass index between 35 and 40 kg/m2 with at least one serious weight-related comorbidity, including but not limited to diabetes, obstructive sleep apnea, hypertension, and coronary artery disease. ■ Body mass index between 30 and 35 kg/m 2 with uncontrollable type 2 diabetes or metabolic syndrome. Besides being a primary bariatric operation, LSG has also been used as a bridging procedure in super morbid obese patients (BMI of 50 kg/m2 and above) before biliopancreatic diversion with duodenal switch (BPDDS). Additionally, LSG is also a good revisional procedure for patients who fail laparoscopic adjustable gastric banding (AGB). Laparoscopic sleeve gastrectomy is safe for patients with diabetes, metabolic syndrome, and inflammatory bowel disease. LSG is also an effective treatment for type 2 diabetes. Finally, LSG has been safely performed in both adolescents and older adult patients. LSG can also be offered to high-risk patients such as those with child’s A or B liver cirrhosis, and those awaiting kidney, liver, or heart transplant, with the goals of improving eligibility for transplant through weight loss and improving future graft function. As an example, between 2006 and 2016, the number of patients with endstage kidney disease undergoing bariatric surgery increased ninefold, and the use of LSG increased. ADVANTAGES OF SLEEVE GASTRECTOMY Some authors described LSG as a stand-alone procedure with good results with respect to excessive weight loss (EWL) and lower plasma ghrelin levels (Figs. 4A and B). Also, there are numerous reports of morbidly obese patients who underwent LSG as a first step before an intended malabsorptive procedure and lost their excessive weight after LSG, so that further surgery was not necessary. This is important because the disadvantages of the malabsorptive 285
SECTION 2: Laparoscopic General Surgical Procedures A B Figs. 4A and B: Before and after sleeve gastrectomy. procedure are avoided. Perhaps the greatest advantage of the gastric sleeve lies in the fact that it does not involve any bypass of the intestinal tract and patients do not, therefore, suffer the complications of intestinal bypass such as intestinal obstruction, anemia, osteoporosis, and vitamin and protein deficiency. It also makes it a suitable form of surgery for patients who are already suffering from anemia, Crohn’s disease and a variety of other conditions that would place them at high risk for surgery involving intestinal bypass. Sleeve gastrectomy can be performed laparoscopically without much problem in patients who are extremely overweight and this accounts for the rising popularity of the LSG. DISADVANTAGES OF SLEEVE GASTRECTOMY Perhaps the main disadvantage of this form of surgery is that it does not always produce the reduction in weight which people would wish for and, in the longer term, can result in weight regain. This is indeed true of any form of purely restrictive surgery, but is perhaps especially true in the case of the sleeve gastrectomy. Because the procedure requires stapling of the stomach, patients do run the risk of leakage and of other complications directly related to stapling. In addition, as with any surgery, patients run the risk of additional complications such as postoperative bleeding, small bowel obstruction, pneumonia and even death. The risk of encountering any of these complications is, however, extremely small and varies from about 0.5 and 1%. Having said this, the risk of death from this form of surgery at about 0.25% is extremely small. CONTRAINDICATIONS OF SLEEVE GASTRECTOMY Absolute contraindications to LSG include prohibitive anesthesia risks, severe uncontrolled psychiatric illnesses (including certain eating disorders such as malignant hyperphagia), and coagulopathy. Barrett’s esophagus and uncontrolled severe gastroesophageal reflux disease (GERD) are relative contraindications to LSG. Some surgeons do not perform LSG in the presence of Barrett’s esophagus, for fear that a sleeve gastrectomy would preclude a future gastric pull-up procedure, which may be required if Barrett’s esophagus progresses to esophageal cancer. Others do not consider Barrett’s esophagus a contraindication to LSG. Hiatal hernia without esophagitis is not a contraindication to LSG. Performing LSG in patients with known GERD is controversial. RYGB is a better surgical option of weight loss than LSG in patients with severe GERD. SURGICAL TECHNIQUE The patient is positioned in a modified reverse Trendelenburg position with the right arm away from the body. The abdomen is prepared and draped in the customary fashion. Ports are placed in the given order (1–5) according to base ball diamond concept as shown in Figures 5A and B. After exploration of the abdomen and the anterior wall of the stomach, the liver is retracted via fifth port (Fig. 6). The first step is to identify the pylorus by visualizing the prepyloric vein of Mayo and palpating with laparoscopic instruments. The pylorus is a crucial landmark because gastric transection typically begins 6 cm from the pylorus. Dissection should be started with dissection of the short gastric vessels to the point of the angle of His, using either the harmonic scalpel (Ethicon Endo-Surgery) or LigaSure™. The greater omentum is then separated from the greater curvature under protection of the gastroepiploic arcade (Fig. 7). A complete mobilization of the greater curvature ensures that a sizable portion of the posterior fundus is not left behind during gastric transection.
A B Figs. 5A and B: Port position for laparoscopic sleeve gastrectomy. Fig. 6: Exposure of stomach up to angle of HIS. Fig. 7: 6 cm of stomach toward the pylorus is left. At this point, surgeon should assess the hiatus for hernias. Any large hiatal hernia should be repaired using standard laparoscopic techniques. The blood supply to the lesser curvature (i.e., left gastric artery) must be preserved since it will become the sole blood supply to the sleeve after gastric transection. A 36-Fr tube is then positioned along the lesser curvature of stomach as the leading structure for the stapling line to follow. Although experts agree on the need for calibrating the sleeved stomach with a bougie, the optimal size of such a bougie is still debated. According to a survey of 863 surgeons with a cumulative experience of 520,230 procedures, the majority of experts used a bougie size of 36 French. After freeing the omentum, staple should be applied along the greater curvature strictly along the stomach tube using a 60-mm Endo-GIA, Ethicon Endo-Surgery or Auto Suture (Figs. 8A and B). The starting point is 7–8 cm prepyloric to the point of the angle of His. Typically, 4–5 staple lines are needed (Figs. 9A to C). Different types of staplers are available in the market. As the gastric transection proceeds, the height of the staples may need to be adjusted according to the thickness of the tissue. In general, most experts would not use staples with closed height <2.0 mm to transect the antrum (the thicker part of the stomach) or staples with closed height <1.5 mm to transect the rest of the stomach (thinner parts). While transecting the stomach, the surgeon must avoid twisting the staple line along the longitudinal axis and avoid narrowing the sleeve, particularly at the level of the incisura angularis. A twisted or narrowed sleeve can cause distal obstruction, which is responsible for the majority of the occurrences and persistence of staple line leaks in the proximal sleeve. The dissected part of the stomach is withdrawn from the abdomen at port number 3 and the staple line is overstitched by absorbable intracorporeal suturing. This is done not to prevent insufficiency in the staple line but rather to prevent staple line bleeding. It is possible to overstitch only areas of bleeding between the staples, and not the whole staple line. When performing the last stapler firing, it is important to avoid stapling too close to the gastroesophageal junction, which may result in ischemia and postoperative leak. Like most of the bariatric surgery operations, currently there are multiple variations in the technique for the LSG. 287
SECTION 2: Laparoscopic General Surgical Procedures A B Figs. 8A and B: Laparoscopic Endo-GIA stapler. A B C Figs. 9A to C: (A) After dissecting the greater omentum from the greater curvature, a 34-Fr stomach tube is placed along the lesser curvature. The first staple line is then set strictly along the stomach. The starting point of the dissection of the greater curvature is about 7–8 cm prepyloric; (B) The second staple line is set strictly and continued along the stomach tube; and (C) Finishing of the gastric sleeve with the third staple line. The greater curvature is resected to the point of the angle of His.
Some of these variations are: the size of bougie (determines the size of the pouch) beside which the Endo-GIA staplers are placed to divide the stomach, the level at which the surgeons start the division in the central area. Many surgeons leave most of the antrum for its pumping, emptying action and also to avoid the possibility of leak from this thick-walled tough area, and whether to reinforce or not reinforce this long staple line. Five or six ports are used for LSG and the surgeon standing between the patient’s legs. An open technique could be used for the first port, establishing a pneumoperitoneum of 15 mm Hg. Then, two right ports, one left port, and a midline ports are usually sufficient (Figs. 5A and B). The right subcostal trocar is used to insert the fan retractor for the liver. The camera should be placed high between the umbilicus and xiphoid. Initial decompression of the stomach with nasogastric tube (NGT) is preferable. Some surgeons commence the LSG with an opening through the gastrocolic ligament to lesser sac, and the posterior stomach wall is visualized and fine adhesions to the pancreas are divided and the lesser sac totally freed using harmonic scalpel, LigaSure™, or coagulation hook. The left side of the gastroesophageal junction should be cleared off fat to avoid later compromise of the stapling during creation of the sleeve (Figs. 10A to D). Left crus should be exposed completely. Majority of surgeons start the dissection 6 cm proximal to the pylorus, but some European surgeons start the dissection closer to the pylorus. If the dissection starts too close to the pylorus, the antrum will not empty properly and its pumping mechanism will be defective, thus postoperative nausea may occur. The linear Endo-GIA stapler is generally introduced through a right trocar toward the left shoulder and leaves about 1 cm of fat pad along the lesser curvature (3 cm width). This assures adequate blood supply on the lesser curvature for the sleeve. Transaction of the stomach should be started 6 cm proximal to the pylorus and then the anesthesiologist inserts a 36–40-Fr bougie down to pylorus if the LSG is intended as the sole operation, but if only as a preliminary step before duodenal switch, then instead a 60-Fr bougie is used. Kueper et al. considered using a 34-Fr bougie in their study, which results in a pouch of 100 mL. The sleeve is started at the lower end of the crow’s foot. The procedure requires 5–6 firings of the linear cutting stapler (60 mm long, 4.8 mm staple-height, and green cartridge) to divide the entire stomach (Figs. 11A to H). It is important to remove A B C D Figs. 10A to D: Dissection and mobilization of stomach along the greater curvature outside the epiploic arcade. 289
SECTION 2: Laparoscopic General Surgical Procedures A B C D E F G H Figs. 11A to H: Gastrectomy with the help of Endo-GI stapler.
all of the fundus to avoid regain of weight. The vagus nerves anteriorly and posteriorly are preserved for normal gastric emptying. Many surgeons recommend reinforcing the staple line to reduce the risk of bleeding and leak. This can be accomplished by using a buttressing material at the time of stapler firing or by oversewing the staple line. A combination of buttressing and oversewing, however, increased staple line leak rate compared with either method alone in one study was done and there was no significant difference. Oversewing should be done with the bougie still in place to avoid excessive imbrication and narrowing of the sleeve lumen. The resected greater curvature could be extracted in a bag via epigastric or right paramedian port-site after being dilated to two-finger diameter. The typical specimen has the shape of a comma or banana with the fundus at the top. After dividing the stomach, most surgeons use over sewing of the staple-line by continuous or interrupted absorbable sutures to prevent bleeding and leak. Intraoperative testing through an 18-Fr Argyle tube with diluted methylene blue or air under saline using a gastroscope, with concurrent compression of prepyloric area is a complementary step. A Gastrografin® swallow is ordered by many surgeons on the second postoperative day, or others perform this study only if there is a problem. A liquid diet may be commenced on the first postoperative day. POSTOPERATIVE CARE Most patients are admitted for overnight observation after LSG, especially if they have a history of obstructive sleep apnea. Postoperative nausea is the most common complaint and should be treated with scheduled doses of intravenous antiemetics such as ondansetron, with other antiemetics, such as prochlorperazine and scopolamine patch, provided as needed for breakthrough symptoms. Minimizing narcotic use by liberal use of local anesthetic infiltration, transverse abdominis plane (TAP) blocks, and intravenous acetaminophen also contributes to the reduction of postoperative nausea and early discharge. A clear liquid diet is usually started in the morning after the procedure. If the patient tolerates that, they can be advanced to a full liquid diet within 24 hours. Once the patient tolerates a liquid diet and their pain is controlled with oral pain medications, they can be discharged home with instructions to only take crushed or liquid medications and a full liquid diet for 2 weeks A postoperative contrast study is performed after LSG to detect leak by some surgeons but not others. Because most leaks from LSG occur late after patient discharge, routine contrast studies on postoperative day 1 have a very low yield of detecting leaks. RISKS AND COMPLICATIONS OF THE SLEEVE GASTRECTOMY As with all forms of weight loss surgery, the vertical gastrectomy does carry risk and these will clearly vary from one patient to the other. In modern series, the overall mortality rate of LSG is approximately 0–1.2%; the overall morbidity rates range from 0 to 17.5%. Complications include: ■ Bleeding to 15% ■ Gastric leakage and fistula 1.0% ■ Strictures 0.26–4% ■ Deep vein thrombosis 0.5% ■ Nonfatal pulmonary embolus 0.5% ■ Postoperative bleeding 0.5% ■ Splenectomy 0.5% ■ Acute respiratory distress 0.25% ■ Pneumonia 0.2% ■ Death 0.25% BLEEDING AFTER SLEEVE GASTRECTOMY Postoperative bleeding after LSG has been described in up to 15% of cases. It can occur within the lumen of the stomach, intra-abdominally, or at the trocar/incision sites. In a retrospective study of over 175,000 LSGs performed from 2015 to 2016, 0.6% were complicated by postoperative bleed. Bleeding after LSG was associated with higher rates of complications, readmission, reoperation, and mortality at 30 days. With bleeding, the mortality rate increased over 10-fold from 0.07 to 0.99%. In multivariate analysis, bleeding was associated with patient factors such as older age, prior cardiac procedure, hypertension, renal insufficiency, therapeutic anticoagulation, diabetes, obstructive sleep apnea, as well as technical factors such as larger bougie size and longer operative length. Staple-line reinforcement or oversewing and higher BMI were protective against bleeding LEAK AFTER SLEEVE GASTRECTOMY Although LSG does not involve an anastomosis, it is more susceptible to a leak than RYGB (2.4 vs. 0.7%) because of a long staple line and high intraluminal pressure. As explained above, the high luminal pressure is generated by a narrowsleeved stomach sealed between an intact pylorus and lower esophageal sphincter. Leaks that occur after LSG are also less likely to close spontaneously because of the high luminal pressure. Other etiologies, besides a high intraluminal pressure, that also contribute to staple line leaks include ischemia, hematoma formation, and staple misfiring. Besides (rare) manufacturing issues, staple misfiring can be due to improper use of the stapler or improper selection of the staple height. When choosing staple cartridges, surgeons must be aware of the progressive decrease in the thickness of the gastric wall from the antrum to the fundus and adjust the 291
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