Obesity Surgery

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

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. Contraindications
   1. High risk cardiopulmonary disease
   2. Ongoing Drug Abuse, Alcohol Abuse or other uncontrolled mental health disorder
   3. Reversible pathologic causes of Obesity (e.g. endocrine disorder)
   4. Poor insight into the risks, benefits, lifestyle investment, alternative options, or expected outcomes
3. 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: Weight loss 30-40% at 1 year and 25% at 10 years
      4. Perioperative mortality: <0.3%
      5. Disadvantages
         1. Malabsorption of iron, B12 and calcium
         2. Technically difficult with higher morbidity
   2. Laparoscopic Adjustable Gastric Banding (introduced in 2006)
      1. Reversible and tension can be adjusted via port
      2. Replaces Vertical Banded Gastroplasty
      3. Weight loss 21% at 1 year and 13% at 10 years
4. Procedures: Other newer procedures
   1. Biliopancreatic Diversion (introduced in 2004)
      1. Very effective in super-obese patients (BMI>50 kg/m)
      2. Weight loss 40% at 1 year and 30-40% at 10 years
   2. Gastric Sleeve (introduced in 2008)
      1. Lateral Stomach excised leaving a smaller residual Stomach pouch
      2. Promising new procedure with high efficacy and lower adverse effects (e.g. no dumping)
5. Procedures: Not recommended
   1. Jejunoileal Bypass (Distal Gastric Bypass)
      1. Less commonly performed since 1985 (with a few exceptions)
   2. Vertical Banded Gastroplasty (VBG or Stomach stapling)
      1. Less commonly performed since 1989 due to low long-term efficacy
         1. Replaced by Adjustable Gastric Banding
      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. These procedures not recommended by NIH panel
      1. Significantly higher risk of complications
6. Complications: Acute serious complications
   1. Perioperative Mortality
      1. Procedure Type
         1. Roux-en-Y gastric bypass (RYGB): <0.3% mortality
         2. Biliopancreatic Diversion (BPD-DS): <0.3% mortality
         3. Laparoscopic Adjustable Gastric Banding (LAGB): <0.1% mortality
      2. Patient factors: Highest risk
         1. Body Mass Index (BMI) over 60 kg/m2: 3% mortality
         2. Age over 60 years: 1% mortality
      3. Patient factors: Additive risks (Mortality increases from 0.2% up to 2.4% if at least 4 criteria are present)
         1. Age over 45 years old
         2. Hypertension
         3. Male gender
         4. Pulmonary Embolism risk (DVT history, Pulmonary Hypertension, Obesity-related hypoventilation)
         5. Body Mass Index >50
   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. Heart Rate over 120 associated with Abdominal Pain increases Specificity
      4. Evaluation
         1. CT Abdomen with contrast (only 60% sensitive)
         2. Urgent surgical consultation
            1. May require exploration despite negative CT Abdomen
   4. Internal Hernia (occurs in up to 3% of retrocolic bypass procedures)
      1. Presentation
         1. Most common in first 6-18 months post-operatively
         2. Presents with colicky Epigastric Pain that worsens with eating
         3. Occurs in those with the greatest weight loss
      2. Evaluation
         1. Requires immediate surgical consultation
         2. Consider abdominal CT if suspected
7. 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
8. 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. Lactose Intolerance
      7. Beef intolerance (due to heightened sense of taste and smell)
      8. Calcium malabsorption
      9. Micronutrient deficiency (Copper deficiency, Zinc Deficiency)
      10. Vitamin A deficiency
      11. 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)
         1. Supplement with more dietary protein
         2. Consider Biotin
      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. Panus: Paniculectomy indications
      1. Refractory skin irritation
      2. Panus severe enough to cover genitalia
9. Efficacy
   1. Bariatric Surgery may cure diabetes in morbid Obesity
      1. Rubino (2002) Ann Surg 236:554-9
   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 292:1724-37
10. Labs: Preoperative evaluation
    1. Comprehensive metabolic panel (renal and hepatic panel)
    2. Complete Blood Count with platelets
    3. Coagulation studies (INR and PTT)
    4. Fasting lipid panel
    5. Thyroid Stimulating Hormone
    6. Vitamin D (25-hydroxyvitamin D)
    7. Vitamin B12
    8. Vitamin B6
    9. Vitamin B1
    10. Urinalysis
    11. Chest XRay
    12. Electrocardiogram
11. 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
       6. Serum Protein
       7. Serum Albumin
       8. Serum Ferritin
       9. Serum Vitamin B12
       10. Serum 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. Serum Ferritin
       5. Serum Vitamin B12
       6. Serum Vitamin D
       7. Serum Vitamin A
       8. Other labs to consider
          1. Serum Thiamine
          2. Serum Copper
          3. Serum Zinc
          4. Serum Magnesium
          5. Serum Vitamin B6
12. Management: Pre-operative Evaluation
    1. Preoperative bariatric evaluation is identical to that in non-obese, non-Bariatric Surgery patients
       1. Exceptions: Obstructive Sleep Apnea and Venous Thromboembolism
    2. Obstructive Sleep Apnea (not yet evaluated)
       1. Uncontrolled Sleep Apnea is a significant risk factor for anastomotic leak
       2. Obstructive Sleep ApneaPrevalence approaches 75% of patients pursuing Bariatric Surgery
       3. Delay procedure for Sleep Apnea evaluation with formal polysomonography
          1. If positive for Sleep Apnea, start CPAP and delay surgery for 4 weeks
    3. Venous Thromboembolism prophylaxis
       1. Common (1-3%) and a leading cause of mortality following Bariatric Surgery
       2. Risk Factors
          1. Body Mass Index >60 kg/m2
          2. Chronic Leg Edema
          3. Obstructive Sleep Apnea
          4. Prior thromboembolism
       3. Best prophylactic strategy is unclear
          1. Removable IVC Filters are commonly used in high risk patients (but inadequate evidence)
       4. Reasonable strategy
          1. Well-fitted Compression stockings
          2. Early ambulation
          3. Enoxaparin 30 mg bid (40 mg bid if BMI>50)
          4. Consider removable IVC Filter for high risk patients
13. 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 chewable once to twice daily (twice if status-post roux-en-y)
       2. Vitamin B12 Supplementation (1000 mcg IM monthly or 350 mcg orally daily)
       3. Calcium 1200 to 1500 mg daily
       4. Vitamin D 800 IU daily (2000 IU daily if status-post roux-en-y)
       5. Iron Supplementation 18-27 mg/day (higher in menstruating women)
       6. Maintain adequate dietary protein intake (see above)
       7. Additional supplements if deficiency identified (recheck monthly until normal)
          1. Thiamine 50 mg orally daily for 6 months
          2. Vitamin B6 50 mg orally daily
          3. Folate 1 mg orally daily
14. 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. Pregnancy
       1. Delay pregnancy for >18-24 months post-procedure
       2. Supplement
          1. Protein: Additional extra 10 grams per day
          2. Vitamin B12: 1000 mcg sublingual weekly
          3. Folic Acid 800 mg orally daily
          4. Iron 325 mg orally daily
          5. Vitamin C 500 mg orally daily
          6. Calcium 1200 mg orally daily
          7. Prevent additional weight loss and expect weight gain during pregnancy
          8. Consider adjustment of band pressure
    4. Continued education and reevaluation
       1. Dieticians
       2. Nurses
       3. Surgical follow-up
15. References
    1. Balsiger (2000) Mayo Clin Proc 75:673-80
    2. Buchwald (2004) JAMA 292:1724-37
    3. Choban (1997) J Am Coll Surg 185:593-603
    4. Virji (2006) Am Fam Physician 73:1403-8
    5. Schroeder (2011) Am Fam Physician 84(7): 805-14