| Obesity is a major health issue in America. According to the recent NIH consensus report, the majority of Americans are overweight. Researchers and physicians realize that obesity is a chronic condition, like hypertension or diabetes, influenced by genetic, metabolic, and environmental factors. The pathogenesis of morbid obesity involves more than just a lack of willpower or a sedentary lifestyle. Obesity contributes to the development of numerous life-threatening or disabling disorders including coronary heart disease, hypertension, Type II diabetes mellitus, hyperlipidemia, degenerative joint disease, and obstructive sleep apnea. An estimated $45 billion is spent annually in the United States treating diseases associated with obesity, with total costs to society estimated at $140 billion. Annual healthcare costs are 44% higher for patients with a body mass index (BMI) > 35 compared to patients with a BMI between 20-24. Significant weight reduction in the morbidly obese has been demonstrated to improve or reverse co-morbid illness, while benefiting psychological, social, and economic well being.
Obesity is defined as being over 125% of ideal body weight as determined by the Metropolitan Life Insurance Table. Patients with severe or morbid obesity are 200% or 100 lbs. over ideal body weight. The BMI is a better indicator of excess body fat. The BMI is the individualíss weight in kilograms divided by the square of the height in meters (kg/m2). A BMI between 25 and 29.9 is considered; overweight (recently lowered from 27 by the NHLBI). A BMI > 30 defines obesity, while a BMI > 40 represents severe or morbid obesity. Superobesity, designated by a BMI > 50, is frequently accompanied by multiple co-morbid medical conditions.
Medical Treatment
Tremendous resources are expended on diets and weight reduction plans, with $30 billion annually spent on commercial weight loss programs alone. Unfortunately, evidence demonstrating long-term success with medical, pharmacological, diet, exercise and behavioral therapies is absent. The majority of reported trials consist of short-term studies ranging from 10 weeks to one year, with an average weight-loss of less than 15 kg. Combined diet and behavior modification programs appear to provide the greatest benefit, though results in the severely obese remain poor. Sustained weight reduction requires life-long behavior modification, and weight regain after completion of a dietary/behavior modification program occurs in the majority of severely obese individuals. This "yo-yo" phenomenon poses its own health risk.
Surgical Treatment
Surgical procedures to treat obesity can be classified as malabsorptive or restrictive. Malabsorptive procedures include the jejuno-ileal bypass and the biliopancreatic bypass. The jejuno-ileal bypass has largely been abandoned due to the development of structural liver abnormalities in one-third of patients and clinical cirrhosis in as many as 10%. In the biliopancreatic bypass, bile and pancreatic juices draining into the duodenum are diverted to the terminal ileum by a long Roux-en-Y limb, in addition to gastric partitioning. Excellent weight loss results, however the procedure is not used widely because of the greater nutritional and metabolic risks.
Restrictive procedures include the vertical banded gastroplasty (VBG) and gastric banding. A 15 to 30 ml proximal gastric pouch is created restricting food intake. The gastric bypass (RYGB) also involves the creation of a small gastric pouch which is drained by a Roux-en-Y jejunal limb. This operation combines gastric restriction with a minimal degree of malabsorption. An added benefit is the limitation on the intake of simple sugars, which produce the dumping syndrome. The VBG and the RYGB are the most commonly performed open obesity procedures.
The indications for gastrointestinal surgery for severe obesity were outlined in the 1991 NIH Consensus Development Statement. Candidates for operative intervention should have a BMI > 40 kg/m2, or a BMI > 35 kg/m2 when associated with high-risk co-morbid conditions. In addition, the consensus panel recommended that a surgeon with substantial experience with the appropriate procedure should perform the surgery, working in a clinical setting capable of supporting all aspects of management and assessment. Lifelong medical surveillance after the surgical procedure is necessary.
Perioperative complication rates are acceptable following open RYGB. Reported mortality rates range from 0.5 to 1.5%. Anastamoticleakage occurs in 2%, with wound infection rates of 8%. Incisional hernia develops in 5 to 20 % of patients following the open procedures. Weight loss following RYGB is typically 60 to 70% of excess body weight. Appropriate food selection and a regular exercise program (walking 25 to 30 minutes 4-5 times/week) improves the results. Micronutrient deficiencies have been reported following RYGB, and lifelong multivitamin/mineral supplementation is mandatory. Long-term surveillance for vitamin B12 and iron deficiency is required.
Reversal or improvement in co-morbid medical conditions including diabetes mellitus, sleep apnea and obesity hypoventilation syndrome, hypertension, hyperlipidemia, and degenerative joint disease has been demonstrated following gastric bypass surgery. A recent study showed that Type II diabetics treated medically had a mortality rate 3 times that of a comparable group undergoing gastric bypass surgery. Improved mobility and exercise tolerance are also observed.
Laparoscopic Obesity Surgery
The laparoscopic Roux-en-Y gastric bypass is constructed in a similar fashion as the open procedure, with a 15 to 30 ml divided; gastric pouch. Weight loss parallels that of the open procedure, although long-term follow-up is lacking. As with all laparoscopic procedures, the surgeon should be experienced in the surgical management of obesity. Benefits include reduced hospital stay (typical loss of 2 to 3 days), more rapid return to normal activity, improved cosmesis, and a marked reduction in the incidence of incisional hernia.
Technical considerations limit laparoscopic RYGB to patients weighing less than 350 lbs. Patients with multiple prior intra-abdominal operations or large, complex ventral hernias pose additional technical difficulties.
The surgical team performing laparoscopic gastric bypass procedures at UT-Southwestern has extensive experience with open gastric bypass as well as advanced laparoscopy. A monthly support group is available for patients who have had gastric bypass surgery and patients considering surgery for obesity.
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