Science Behind Sleeve Gastrectomy
Laparoscopic sleeve gastrectomy is a restrictive procedure without the malabsorptive component present in other bariatric procedures. It involves resection of two-thirds of the stomach to provide increased satiety and decreased appetite.1 Through restriction in the stomach size, the intragastric volume is less able to accommodate a large volume of food leading to decreased food consumption. In addition, a lower volume of food leads to earlier distention of the stomach causing firing of stretch receptors in the gastric wall. These signals are communicated via the vagus nerve to the nucleus of the solitary tract in the brainstem which then signals to the hypothalamus and then the cerebral cortex leading to the perception of satiety.2 Decreased levels of ghrelin that occur as a result of resection of the gastric fundus, the location of ghrelin production, also likely leads to greater satiety.3 Other purely restrictive procedures such as laparoscopic gastric band placement involve surgical implantable devices leaving a foreign body in place for future increased restriction if necessary, whereas the sleeve gastrectomy surgically and permanently reduces the size of the remnant stomach.
Sleeve gastrectomy for weight loss was first described by Marceau in 1993 as a component of biliopancreatic diversion.1 Laparoscopic sleeve gastrectomy (LSG) was performed as a component of biliopancreatic diversion with duodenal switch (BPD-DS) in 2000 by Ren, et al. and subsequently used as the initial stage of a two-staged approach for super-morbidly obese patients. Super-morbidly obese patients have more complications after weight loss surgery4 and higher rates of failure.5 Therefore, a two-stage approach, consisting of LSG followed by laparoscopic Roux-en-y gastric bypass (LRYGB) was first performed by Regan et al. in 2003 to overcome these challenges in the super-morbidly obese patients.6 LSG revised to laparoscopic BPD-DS has also been described to achieve similar results.7 Over time the operative approach to morbid obesity through utilization of LSG has been modified and LSG is often now used in isolation due to its demonstrated effectiveness in regards to EWL and resolution of obesity comorbid conditions. LSG has also been utilized in a variety of other settings creating much interest into this procedure.
- Primary weight loss procedure
- Initial stage of two-staged approach for weight loss
- Component of laparoscopic BPD-DS
- Patient must meet NIH guidelines typically required for insurance compensation although other requirements may be used depending on the individual patient situation. Please refer to the SAGES website at the below reference for extensive discussion of this topic.8
Antiembolic precautions are taken and appropriate preop antibiotics are administered. A 12-mm optical trocar is placed under direct vision approximately 15 cm below the xiphoid and 3 cm to the left of midlin. A 45-degree angled laparoscope is placed through the port into the peritoneal cavity and 12-mm port is placed in the left lateral flank, medial to the edge of the colon with the patient in a supine position and at the same level as the periumbilical port. Next, a 5-mm trocar port is placed along the left subcostal margin between the xiphoid process and the left flank port. Another 12-mm port is placed in the right epigastric region and a fourth 12 mm port was placed in the mid-epigastric region caudal and medial to the previous port. The liver is elevated and this provides adequate visualization of the entire stomach during the gastrectomy. The pylorus of the stomach is then identified and the greater curve of the stomach elevated. A ultrasonic scalpel is then used to enter the greater sac via division of the greater omentum. The greater curvature of the stomach is then dissected free from the omentum and the short gastric blood vessels using the laparoscopic ultrasonic scalpel. The dissection is started 5 cm from the pylorus and proceeds to the Angle of His. A 9.8 mm gastroscope is then passed under direct vision through the esophagus, stomach, and into the first portion of the duodenum. The gastroscope is aligned along the lesser curvature of the stomach and used as a template to perform the vertical sleeve gastrectomy beginning 2 cm proximal to the pylorus and extending to the Angle of His. An endoscopic linear cutting stapler is used to serially staple and transect the stomach staying just to the left and lateral to the endoscope. The gastrectomy is visualized with the endoscope during the procedure. The transected stomach, which includes the greater curvature, is completely freed and removed from the peritoneum through the left flank port incision. The staple line along the remaining tubularized stomach is then tested for any leak through insufflations with the gastroscope while the remnant stomach is submerged under irrigation fluid. The staple line is concurrently evaluated for bleeding both intraperitoneally with the laparoscope as well as intraluminally with the gastroscope. A 19-French Blake drain is left in the left upper quadrant along the sleeve gastrectomy staple line. We do close the fascia of the left flank port site with an absorbable suture on a transabdominal suture passer, to prevent bowel herniation but do not close the fascia defects at the remaining port sites.
Several technical variations on the laparoscopic sleeve gastrectomy have been reported. The main difference is the size of dilator utilized to create the sleeve during stapling and transection. A wide range sizes for bougie dilators have been employed to size the gastric pouch. Although some have suggested bougie size impacts %EWL,24 studies are non uniform and give variable results in regards to bougie size and weight loss. Furthermore, different bougie sizes utilized by a single group failed to demonstrate any effect of bougie size on %EWL,16, 25 indicating bougie size may have little effect on achieved weight loss. Some studies have employed the use of a 9.8 mm gastroscope for gastric sleeve sizing which falls along the smaller range of sizes used for gastric sleeve sizing. It provides the advantage of allowing intraluminal visualization during gastric stapling, and post-stapling visualization for evaluation of staple line hemorrhage and for a post-transection leak test. Whether or not the small diameter leads to an increased risk of stricture is not known, but a limited number of studies using the gastroscope do not report an unusually high level of post-operative stricture formation, so it likely is a safe and effective alternative to Bougie dilators for sizing the gastric sleeve.
On post-operative day #1 all patients undergo a gastrograffin swallow study to evaluate for leak or stricture. We do find that some patients experience delayed passage of the contrast likely due to edema in the narrow gastric remnant. Delayed passage of contrast does not prevent discharge from the hospital, however, as it is felt this is due to post-operative edema and will resolve over the next several days post discharge. Following gastrograffin swallow, if the patient is medically stable with adequate pain control, the patient is discharge after dietary instruction by a bariatric dietician to follow-up 7-10 days post discharge. Subsequent follow-up occurs at one month, 3 months, 6 months and 1 year post surgery and then yearly thereafter. Routine bariatric labs to evaluate for nutrient deficiencies are performed at 6 months, one year and then yearly following LSG.
Outcomes Following Laparoscopic Sleeve Gastrectomy
Initially LSG was utilized as a component of a two-staged surgical approach to morbid obesity, followed by LRYGB or BPD-DS. When utilized as the initial stage of a two-staged approach, patients experienced decreased weight, comorbidities and decreased American Society of Anesthesiologists (ASA) physical status score after first-stage LSG prior to LRYGB,9 indicating LSG may decrease the potential morbidity and/or mortality in high-risk patients prior to LRYGB. Studies reporting on outcomes after utilization of the two-stage approach report %EWL of 35-45%10, 11 prior to revision to LRYGB, with further weight loss as high as 64% EWL of preoperative weight after revision.10 Although the %EWL is lower compared to other studies of LSG, follow-up was shorter likely accounting for these differences. Resolution of comorbid conditions including hypertension, diabetes mellitus, obstructive sleep apnea, hyperlipidemia, and gastroesophageal reflux disease have been reported with continued improvement after revision. Cottam, et al. reported a significant decrease in comorbid conditions from 9 conditions present prior to LSG, to 6 conditions present after LSG and prior to LRYGB, with a further decrease to 2 conditions after LRYGB. Although initially utilized to decrease perioperative morbidity/mortality during the higher risk but potentially more beneficial procedures, early data demonstrated that the LSG was highly effective in terms of both %EWL and comorbidity resolution. Mean %EWL has been reported between 33-83% at follow-up of 6-36 months when LSG was performed as a primary procedure or part of a two-staged procedure.12-14 The average expected %EWL has been estimated at 61%.15 A recent retrospective study of 247 patients demonstrated one and two year follow-up data with %EWL of 78 and 75% respectively16. Although not extensively reported, multiple comorbidities have been shown to be relieved after LSG. Hypertension, diabetes mellitus, obstructive sleep apnea, hyperlipidemia, and gastroesophageal reflux are the most common comorbidities studied. Resolution rates include hypertension, 15-100%, diabetes mellitus, 47-100%, obstructive sleep apnea, 56-100%, hyperlipidemia, 45-73%, and gastroesophageal reflux disease, 70-80%.12, 14 Although variable, these results are promising and further long- term follow-up with randomized controlled trials comparing other weight loss procedures is necessary.
The incidence of complications after LSG has been reported at 0-24%.14 Several large series have demonstrated the most frequently encountered major complications included leaks (0-10%), suture line hemorrhage (0-10%), and major organ injury (0-5%).17 Rates of post-operative stricture are reported at less than 1%10, 18 The overall mortality rate is estimated at 0.39% in the literature.14
LSG vs. LRYGB
There is much interest into the risk/benefit profile of LSG versus LRYGB due to the perceived increased risks associated with LRYGB. Primary LSG has been recently compared to primary LRYGB in a group of Indian patients.19 At one year follow-up %EWL was 76% in the LSG group and 62% in the LRYGB group. Comorobidity resolution in LSG/LRYGB were 83%/92% resolved for hypertension, 78%/98% resolved for diabetes mellitus, 75%/78% resolved for dyslipidemia, and 91%/100% resolved for gastroesophageal reflux disease. Only one major and one minor complication occurred in each group. A prospective, randomized-controlled trial involving 16 patients in each group demonstrated a significantly increased %EWL in LSG as compared to LRYGB at 6 months and one year post-operatively.20 However, a recent prospective randomized controlled trial has reported early 3 month results demonstrating equivalency between LSG and LRYGB in regards to %EWL and resolution of diabetes mellitus.21 It is yet unclear which procedure achieves greater comorbidity resolution and %EWL as comparative studies still have short-term follow-up. LRYGB has been demonstrated to have a %EWL of 63% in a large meta-analysis, although several large studies demonstrate EWL between 68-77%.22 Although variable results are achieved between surgeons and centers, this estimate falls in the range of that seen with LSG, although at the upper end of the reported range of EWL after LSG. A large amount of data is not yet available for LSG making comparison to LRYGB difficult. Additionally, resolution of comorbidites and complication rates are difficult to compare between the two techniques. Two of the major complications after LRYGB include anastomotic leak (2-4%) and gastrojejunal stricture (0.5-4.9%).22 Mortality rates are low in both LSG and LRYGB. Comorbidity resolution is good in both techniques but the literature is not clear on which technique is superior in relieving the common obesity comorbid conditions. One benefit of LSG compared to malabsorptive procedures such as LRYGB and laparoscopic BPD-DS is that endoscopic procedures not possible after surgical reconstruction of the small bowel are possible after LSG. This becomes especially important in evaluating patients with suspected gastritis or biliary pathology which become difficult to evaluate endoscopically after LRYGB or BPD-DS.
LSG vs. Laparoscopic Adjustable Band
LSG has also been compared to laparoscopic gastric banding. Himpens, et al. reported medium-term follow-up data in a prospective randomized study demonstrating that LSG resulted in significantly greater %EWL than gastric banding at one year, 41% and 58%, respectively and three years, 48% and 66%, respectively. Complications were minimal in each group.23
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