Endocrinology Book

Diabetes Mellitus

Obesity

  • Obesity Surgery

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Obesity SurgeryAka: Roux-en-Y gastric bypass, Vertical Banded Gastroplasty, Distal Gastric Bypass, Biliopancreatic Diversion, Gastric Bypass, Gastroplasty, Bariatric Surgery

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  1. Indication: Obesity
    1. Body Mass Index (BMI) >= 40 kg/m2
    2. Body Mass Index (BMI) >= 35 kg/m2 with comorbidity (e.g. Diabetes, CardioMyopathy)
  2. Procedures: Common
    1. Roux-en-Y gastric bypass (RYGB)
      1. Gold standard method today
      2. Description
        1. Stomach partitioned into 20 ml pouch
        2. Pouch anastomosed to jejunum
        3. Remainder of stomach and duodenum bypassed
      3. Efficacy
        1. At 3 years: 68-72% excess Weight Reduction
        2. At 10 years: 55% excess Weight Reduction
      4. Perioperative mortality: 0 to 2.5%
      5. Disadvantages
        1. Malabsorption of iron, B12 and calcium
        2. Technically difficult with higher morbidity
    2. Vertical Banded Gastroplasty (VBG or stomach stapling)
      1. Less commonly done due to low long-term efficacy
      2. Efficacy
        1. At 3 years: 40-63% excess Weight Reduction
        2. At 10 years: 20% excess Weight Reduction
      3. Disadvantages
        1. Less effective than Roux-en-Y Procedure
        2. High surgical revision rate (41-45%)
          1. Due to high rate of staple dehiscence
          2. Once staple line opens, weight gain returns
        3. Higher risk of stricture or GERD
      4. Perioperative mortality: 0-1.0%
  3. Procedures: Other newer procedures
    1. Biliopancreatic Diversion
      1. Very effective in super-obese patients (BMI>50 kg/m)
    2. Adjustable Gastric Banding
      1. Reversible and tension can be adjusted via port
  4. Procedures: Not recommended by NIH panel
    1. Distal Gastric Bypass
    2. These procedures not recommended by NIH panel
      1. Significantly higher risk of complications
  5. Complications: Acute serious complications
    1. Perioperative Mortality (1%)
    2. Thromboembolic complications
      1. See peri-operative thromboembolism prophylaxis below
    3. Anastomotic Leak (and secondary Sepsis)
      1. Leak at anastomosis or banding site
      2. Requires emergency evaluation
      3. Presentation
        1. Severe Abdominal Pain
        2. Fever
        3. Hypotensive shock
      4. Evaluation
        1. Upper GI or CT Abdomen with contrast
        2. Urgent surgical consultation
  6. Complications: Short-term
    1. Wound infection
      1. Occurs up to 3 weeks after surgery
      2. Risk of developing Incisional Hernia
    2. Stomal stenosis
      1. Results in Vomiting even with liquid meals
      2. Evaluate Upper gastrointestinal series
      3. Treat with dilatation via upper endoscopy
    3. Peptic ulcer at surgical anastomosis (marginal ulcer)
      1. Evaluate with upper endoscopy
      2. Avoid NSAIDs
    4. Constipation
      1. Maximize hydration (96 ounces clear fluid daily)
      2. Minimize Narcotic Analgesics post-operatively
      3. Avoid Bulk Laxatives after gastric banding
        1. Risk of obstruction
  7. Complications: Long-term
    1. Cholelithiasis or Cholecystitis (30% of patients)
      1. Consider Cholecystectomy at time of Bariatric Surgery
    2. Nephrolithiasis related to Calcium Oxalate Stone formation
    3. Secondary Hyperparathyroidism
    4. Malabsorption
      1. See lab monitoring below
      2. See post-operative diet below
      3. Dumping Syndrome (60% of patients)
      4. Protein-calorie malnutrition
      5. Fat malabsorption
      6. Calcium malabsorption
      7. Micronutrient deficiency (Copper deficiency, Zinc deficiency)
      8. Vitamin A deficiency
      9. Anemia due to Vitamin Deficiency
        1. Iron Deficiency Anemia
        2. Folate Deficiency
        3. Vitamin B12 Deficiency
    5. Overall body changes
      1. Hair thinning (due to rapid weight loss)
      2. Metrorrhagia
      3. Fertility increases
        1. Use reliable Contraception to avoid pregnancy within first 2 years after surgery
        2. Food intolerance
          1. Lactose Intolerance
          2. Beef intolerance (due to hypersensitivity to taste and smell)
    6. Altered medication absorption
      1. Gastric banding (gastric restriction)
        1. Consider switch from XR to immediate release agents
        2. Take one medication at a time
      2. Gastric Bypass
        1. Monitor Digoxin and Levothyroxine dosing closely
        2. Exercise caution when using azole Antifungals
    7. Bacterial overgrowth
      1. Presents with abdominal distention, proctitis, nighttime Diarrhea, and arthralgias
  8. Efficacy
    1. Bariatric Surgery may cure diabetes in morbid Obesity
      1. Rubino (2002) Ann Surg 236:554
    2. Significantly reduces morbidity and mortality
      1. Diabetes Mellitus 76% resolved or improved
      2. Total and LDL Cholesterol was significantly reduced
      3. Hypertension resolved in 61% (improved in 78%)
      4. Sleep Apnea resolved or improved in 83%
      5. Mortality over 9 years reduced from 28% to 9%
      6. Buchwald (2004) JAMA 292:1724
  9. Labs: Monitoring schedule post-procedure
    1. Three months after surgery
      1. Complete Blood Count
      2. Blood Glucose
      3. Serum Creatinine
    2. Six months after surgery
      1. Complete Blood Count
      2. Blood Glucose
      3. Serum Creatinine
      4. Serum Calcium
      5. Liver Function Tests, Protein, Albumin
      6. Ferritin, Vitamin B12, Folic Acid
    3. Nine months after surgery
      1. Complete Blood Count
      2. Blood Glucose
      3. Serum Creatinine
    4. One year after surgery and then every year therafter
      1. Complete Blood Count
      2. Blood Glucose
      3. Serum Creatinine
      4. Consider Vitamin D
  10. Management: Peri-operative thromboembolism prophylaxis
    1. Risk factors
      1. Body Mass Index >60 kg/m2
      2. Chronic Leg Edema
      3. Obstructive Sleep Apnea
      4. Prior thromboembolism
    2. Standard prophylaxis (moderate risk patients)
      1. Low Molecular Weight Heparin at prophylactic dose and
      2. Compression stockings
    3. Prophylaxis for high risk patients
      1. Low Molecular Weight Heparin at therapeutic dose and
  11. Management: Diet post-operative
    1. Dietary changes to avoid over-distention and Vomiting
      1. Immediately after Gastric Bypass
        1. Start with clear liquids and gradually progress to regular foods over first 3 months
      2. Longterm
        1. Start meal with protein portion to ensure adequate protein intake
        2. Cut food into small bite size amounts (as if using toddler utensils)
        3. Chew well (to applesauce consistency) before swallowing
        4. Eat slowly and without distraction (finish a meal within 30 minutes)
        5. Avoid drinking fluids 30 minutes before and 30-60 minutes after each meal
        6. Identify fullness sensation and stop eating immediately when you feel this
    2. Other dietary changes
      1. Limits foods with substantial simple carbohydrates or high fats (avoids dumping)
      2. Stay hydrated by taking 64 ounces non-caffeinated fluid and avoiding alcohol
    3. Vitamin supplementation
      1. Multivitamin
      2. Vitamin B12 Supplementation (IM monthly or PO qd)
      3. Calcium 1200 to 1500 mg daily
      4. Iron Supplementation in menstruating women
      5. Maintain adequate dietary protein intake (see above)
  12. Follow-up: Post-operative
    1. Imperative that patients continue life-long care
      1. Compliance with diet above
      2. Maintenance of regular physical Exercise program
    2. Monitoring of labs (see above)
    3. Delay pregnancy for >18 months post-procedure
    4. Continued education and reevaluation
      1. Dieticians
      2. Nurses
      3. Surgical follow-up
  13. References
    1. Balsiger (2000) Mayo Clin Proc 75:673
    2. Buchwald (2004) JAMA 292:1724
    3. Choban (1997) J Am Coll Surg 185:593
    4. Virji (2006) Am Fam Physician 73:1403

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