Bariatric Surgery

• Indications: BMI >40, or BMI >35 with obesity-related complications (e.g. OSA, cardiomyopathy, refractory DM)
• Mechanism of effect: reduce caloric intake by modifying anatomy of GI tract, typically resulting in weight loss of 20-50kg
• Types of surgeries:
• Restrictive: limit intake by reducing size of gastric reservoir, with narrow outlet to delay emptying (e.g. gastric stapling, banding, sleeve gastrectomy)
• Malabsorptive: bypass varying portions of small bowel where absorption occurs (e.g. roux-en-Y bypass), with degree of malabsorption depends on length of Roux limb) à typically more effective than restrictive surgeries
• Adverse effects:
• Perioperative mortality: 0.1-2% (PE, anastamotic leak)
• Perioperative complications: VTE, wound infection, bleeding, splenic injury, hernia, SBO
• As Ellen mentioned, VTE is a quite common, and some surgeons preemptively place IVC filters given the high incidence of DVT
• GI complications
• Nausea/vomiting (occurs in 50% of those with restrictive procedures): can result from eating too much/rapidly, anastamotic stricture, or mechanical complication
• Dumping syndrome (occurs 70% of Roux-en-Y cases)
• Early: undigested food contents results in large osmotic load → rapid fluid shifts into small bowel → stimulates release of VIP and serotonin → flushing, dizziness, hypotension, palpitations, diarrhea
• Late: consumption of simple carbohydrates → robust insulin response → hypoglycemia and associated symptoms
• There have been cases where Roux-en-Y surgeries have to be reversed, given episodes of refractory hyperinsulinemia
• Cholelithiasis
• Marginal ulcers: result from gastric acid injuring junction of gastro-jejunostomy
• Malnutrition: particularly iron, calcium, B12, thiamine, folate, fat-soluble vitamins

(Christopher Woo MD, 4/14/11)