Bariatric surgery is currently the most successful approach to rescuing patients with severe obesity and reversing or preventing the development of several diseases associated with obesity. There are an increasing number of surgeries being performed for the treatment of obesity. This rise in procedures can be attributed to the increased population of "extreme obesity" as well as the failure of diet, exercise and medical therapies. Another factor could be the ability to perform the surgery laproscopically. Surgery can be an additional treatment option for patients with a BMI >40 who failed lifestyle changes with or without medication supplementation and have obesity-related comorbid conditions. Surgery alone will not correct any underlying psychological eating disorders. Additionally, reduction of cardiovascular morbidity and mortality does not occur due to weight loss through surgery alone. The Swedish Obese Subjects (SOS) Study, which was an observational study, did show that the average long term weight loss for the surgical patient is 20 kg, versus, no change for those using medical treatment. The SOS study was also able to demonstrate improvements in or prevention of comorbid conditions associated with obesity when compared with similar patients undergoing medical therapy. In a 24-month follow-up evaluation, there was a decreased incidence in hypertension, diabetes and lipid abnormalities, but by 8 years, only a decrease in diabetes was noted. Another notable finding was a decreased caloric intake and greater physical activity in surgery vs. control patients throughout the follow-up period.
Different surgical procedures are available to treat obesity (Fig. 6.3), and have evolved since the first bariatric surgery performed in the 1950s with the introduction of the jejunoileal bypass and subsequently the gastric bypass in 1967.
1. Roux-en-Y gastric bypass (RYGB) limits gastric capacity and causes mild malabsorption. This procedure involves the construction of a proximal gastric pouch whose outlet is a Y-shaped limb of small bowel of varying lengths. The proximal stomach is separated from the remaining portion of the stomach with staples.
2. Biliopancreatic bypass combines a limited gastrectomy with a long Roux limb intestinal bypass, works primarily through malabsorption.
3. Laparoscopic adjustable gastric band is placed around the upper-most portion of the stomach and restricts capacity, usually less than 30 ml in volume. There is restricted passage to the subsequent part of the stomach, leading to weight loss by decreased dietary intake. The band can be adjusted by the infusion of saline through a subcutaneous port.
4. Vertical banded gastroplasty involves stapling the upper stomach to limit gastric capacity.
There is a larger weight loss after gastric bypass compared with other types of surgery, and this may be related to altered gut-to-brain signaling.
Surgery is not without risks however. Among surgeons, there is a learning curve in which those with fewer than 20 procedures had a 5% mortality rate, as compared with greater than 50 had a near zero mortality. The length of surgery also stabilized after 150 cases. Complications also decreased from 12.5% for fewer than 100 cases, to 3% after 150 cases. Such complications include anastomotic leak, subphrenic abscess, splenic injury, pulmonary embolism, wound infection and stoma stenosis. Perioperative mortality is influenced by age; in a young patient with a BMI <50, there was a 1% mortality rate in comparison to a patient with a BMI >60 and comorbidities such as diabetes, hypertension, or cardiovascular disease, the mortality jumped to 2-4%.
Women of reproductive age who have undergone bariatric surgery require counseling and management of subsequent pregnancies. Patients with adjustable gastric banding should be advised that they are at risk of becoming pregnant unexpectedly after weight loss following surgery. All patients are advised to delay pregnancy for 12-18 months after surgery to avoid pregnancy during the rapid weight loss phase in order to avoid malnutrition and small-for-dates features in the neonate. After restrictive procedures (where iron containing foods such as red meat may be poorly tolerated) increased iron is needed. After gastric bypass procedures (in which the duodenum—where most iron is absorbed—is bypassed) increased iron must be taken during pregnancy to allow adequate absorption in the proximal jejunum. Furthermore, adequate calcium intake or supplementation should be verified. Women with a gastric band should be monitored by their general surgeons during pregnancy because adjustment of the band may be necessary. Women who have undergone bypass surgery do not appear to be at undue risk for adverse pregnancy outcomes, and initial results from larger case series have been promising.
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