CHAPTER 28 Bariatric Surgery
Step 1: Surgical Anatomy
♦ The left gastric vessels are the primary blood supply to the proximal lesser curvature of the stomach, from which the gastric pouch is created. Care should be taken to preserve the left gastric vessels during pouch creation.
♦ Several anatomic factors are important to consider during construction of the Roux limb. First, the blood supply of the jejunum is derived from the superior mesenteric artery, and when the mesentery is divided to create the Roux limb, hemostasis is critical. A hematoma in the mesentery can be difficult to manage and can compromise the viability of both the Roux limb and the end of the biliopancreatic limb.
Step 2: Preoperative Assessment and Considerations
♦ A multidisciplinary approach is recommended when offering weight loss surgery to extremely obese adolescents. The team should include an experienced bariatric surgeon, pediatric obesity specialist, nurse, dietitian, and pediatric psychologist or psychiatrist. The program also must have ready access to relevant pediatric subspecialties, including endocrinology, cardiology, gastroenterology, pulmonology, gynecology, and orthopedics for further evaluation or management of specific co-morbidities as needed.
♦ The multidisciplinary team should consider carefully whether the patient and family have the ability and motivation to adhere to recommended treatments preoperatively and postoperatively, including the consistent use of micronutrient supplements.
♦ Adolescents seeking a surgical procedure for obesity should demonstrate a history of sustained efforts to lose weight through changes in diet and physical activity. The most widely accepted body mass index (BMI) criteria for weight loss surgery in adolescents include a BMI of 35 kg/m2 or greater and a severe co-morbidity (severe obstructive sleep apnea, diabetes mellitus type 2, pseudotumor cerebri, or severe and progressive steatohepatitis) or a BMI of 40 kg/m2 or greater with other less severe co-morbidities.
♦ On the day before surgery, patients are limited to clear liquids. No bowel preparation is required. Preoperative medications include low-molecular-weight heparin (40 mg subcutaneously and continued twice daily during postoperative hospitalization) and a second-generation cephalosporin (2 g intravenously). Sequential compression boots are also used perioperatively and should be applied before the induction of anesthesia.
Step 3: Operative Steps (Laparoscopic Roux-en-Y Gastric Bypass)
Anesthetic Considerations
Positioning
♦ Given the patient’s extreme girth, it is ergonomically advantageous to stand on a platform 20 to 40 cm above the floor.
♦ For initial abdominal access, the transparent, bladeless, direct viewing (Optiview, Ethicon Endosurgery, Cincinnati, OH) 12-mm trocar can be used safely and efficiently.
♦ The omentum is first raised cephalad to expose the transverse mesocolon and origin of the jejunum. Exposure of the small bowel is optimized if the table is placed into slight Trendelenburg position and the omentum is tucked carefully under the liver edge.
♦ The transverse mesocolon is grasped just anterior to the duodenojejunal flexure and elevated anteriorly. The jejunum is divided 30 to 50 cm beyond the duodenojejunal flexure using the 45-mm endoscopic stapler (vascular [1-mm] load). As the mesentery contains many vessels, bipolar electrocautery is often needed to achieve full hemostasis in this area despite using a small staple height (Fig. 28-1).
♦ Current practice employs a 75- to 150-cm Roux limb for most patients. A side-to-side jejunojejunostomy is created using the 45 mm stapler with vascular load (Fig. 28-2).
♦ The mesenteric defect is next closed with a running 2-0 silk suture to avoid an internal hernial orifice (Figs. 28-3 and 28-4).
♦ A mesocolic defect is next created through which the retrocolic Roux limb is passed into the lesser sac. This defect will need to be closed around the Roux limb, and Petersen’s defect between the small bowel mesentery and the mesocolon will need to be deliberately closed to prevent internal hernia formation.
♦ The liver retractor is next inserted to expose the gastroesophageal junction. The lesser curve-based gastric pouch will be created around a 34 French orogastric tube. The creation of the gastric pouch begins with perigastric dissection along the lesser curvature approximately 8 to 10 cm inferior to the gastroesophageal junction (usually just below the 2nd major lesser curve vessel), extending cephalad toward the angle of His (Fig. 28-5).
♦ Numerous techniques are available for laparoscopic gastrojejunostomy, including hand sewn, the end-to-end stapled technique with anvil inserted into the pouch laparoscopically, the end-to-end stapled technique with the anvil inserted orally (akin to the percutaneous endoscopic gastrostomy method of gastrostomy), and a linearly stapled technique. The Roux can ascend to the pouch either in an antegastric or retrogastric fashion.
♦ The linearly stapled gastrojejunostomy begins by first bringing the Roux limb into proximity with the inferior end of the gastric pouch. Enterotomies in the end of the Roux limb and the gastric pouch are created, and the stapler is inserted to 2.5 to 3 cm and fired (Figs. 28-6 and 28-7).
♦ Before final closure of the defect, a stent or flexible endoscope is advanced through the anastomosis to ensure that suturing of the defect does not compromise the patency of the anastomosis (Fig. 28-9).
♦ On completion of the bypass (Fig. 28-10), the integrity and patency of the anastomosis are assessed laparoscopically with intraluminal air insufflation under saline. A closed suction drain is usually placed near the anastomosis and removed after the contrast study on postoperative day 1.
Step 4: Postoperative Care
♦ Typically, patients are extubated in the operating room after transfer to the hospital bed. They are cared for in a monitored, non–intensive care unit setting, and maintenance fluids are administered based on lean body weight (typically 50% of actual weight).
♦ Early warning signs of complication include fever, tachycardia, tachypnea, increasing oxygen requirement, oliguria, hiccoughs, regurgitation, left shoulder pain, worsening abdominal pain, a feeling of anxiety, or acute alteration in mental status. These signs warrant aggressive attention and appropriate investigation because they may signal gastrointestinal leak (anastomosis or staple lines), pulmonary embolus, bowel obstruction, or acute dilation and impending rupture of the bypassed gastric remnant.
♦ Routinely, a water soluble upper gastrointestinal contrast study is obtained on postoperative day 1. After satisfactory passage of contrast is documented, clear liquids are started and subsequently advanced to a high-protein liquid diet for the first month after operation.
♦ Dietary advancement after the first month is a methodical process of introducing new items of gradually increasing complexity toward the goal of a well-balanced, small portion (~1 to 1.5 cup per meal) diet, which ensures a daily intake of 1 g of protein per kilogram of ideal weight.
♦ Nonsteroidal anti-inflammatory medications should be avoided to reduce the risk of intestinal ulceration and bleeding. Ursodiol and ranitidine are prescribed for 6 months, which is the practice for most adult bariatric programs. Postoperative vitamin and mineral supplementation typically consists of two pediatric chewable multivitamins, a calcium supplement, and an iron supplement for menstruating females. B-complex vitamins are supplemented for 6 months, primarily to augment thiamine and folate supplementation.
Step 5: Pearls and Pitfalls
♦ Minimally invasive bariatric surgery is one of the most technically difficult operations to perform. Adequate technical training is critical before embarking on minimally invasive surgical treatment for adolescent severe obesity and at a minimum should take an accredited course of study in bariatric surgery (www.asbs.org; www.sages.org) and perform procedures first proctored by an experienced laparoscopic bariatric surgeon.
♦ Longer instruments and staplers can be of benefit, especially for accomplishing the gastric portion of the operation. A gastric bypass comprises two different operations: a small bowel and a proximal stomach component. Particularly in the tall patient, there can be a great distance between those two fields, and therefore it is important to ensure that trocars are placed low enough that the small bowel portion can be done but high enough to permit work on the top of the stomach.
♦ When exposure of the proximal stomach is difficult, consider increasing insufflation pressure. Normal intra-abdominal pressure is approximately 4 or 5 mm Hg, whereas in the morbidly obese patient, intra-abdominal pressure is 10 to 12 mm Hg or higher. Therefore, if you are only using a pressure of 15 mm Hg, you will have very little free room in the abdomen in which to work. An increase in pressure to 16 to 18, or even occasionally up 20 mm Hg, for brief periods to expose the proximal stomach can be quite beneficial.
♦ Better muscular relaxation can be extremely important when exposure is poor. The best relaxation may not be seen even when neuromuscular stimulation demonstrates only one twitch in the standard “train of four” measurement done by anesthesiologists. This is because the diaphragm is much more resistant to relaxation than other skeletal muscle, and the laparoscopic surgeon will find reduced intra-abdominal domain as much as 5 minutes before the anesthesiologist can detect any return of muscle function from facial muscle stimulation. Proper muscle relaxation can make the difference between inadequate exposure and being unable to complete the procedure or being able to complete the operation safely.
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