Bariatric Surgery: Postop Monitoring


There are 5 surgical procedures endorsed by the American Society of Metabolic and Bariatric Surgery:

  • Sleeve gastrectomy (SG; 70%)
  • Roux-en-Y gastric bypass (RYGB; 25%)
  • Laparoscopic adjustable gastric banding (LAGB; 3%)
  • Biliopancreatic diversion with duodenal switch (BPD/DS; 2%)
  • Single anastomosis duodenal-ileal bypass with sleeve gastrectomy (SADI-S)
    • Newest procedure; less data available (remainder of blog post will focus on the first 4 procedures above)
Source: UpToDate

Each surgery type has advantages and disadvantages: 

Source: Mechanick, et al. 2019

Furthermore, each surgery type has different long-term effects, including significant effects on nutrition.

Postop Monitoring

The guidelines for postop monitoring are complicated, emphasizing an individualized approach depending on the type of bariatric surgery performed. 

For long-term success and early identification of complications, lifelong follow-up is recommended after bariatric surgery.

Source: Mechanick, et al. 2019

An 2020 JAMA article offers a more concise approach to general follow-up: 

Source: Chen, et al. 2020

Appropriate monitoring also depends on recognition of the potential complications following bariatric surgery, which vary depending on the type of procedure performed: 

Source: Chen, et al. 2020

Dumping syndrome, for instance, is a common complication of bariatric surgery. Alterations in gastric anatomy and interference with intrinsic gastric innervation disturb physiologic gastric emptying mechanisms and allow a substantial amount of undigested food to rapidly reach the small intestine. Dumping syndrome is a constellation of symptoms that can be categorized as early dumping or late dumping.

Source: Narayanan, et al. 2016
  • Early dumping syndrome occurs within 1 hour after a meal. Because of the hyperosmolality of ingested food, rapid fluid shifts occur from the plasma to the intestinal lumen, resulting in hypotension and SNS response. Early dumping is characterized by GI symptoms (e.g., abdominal pain, bloating, borborygmi, nausea, diarrhea) and vasomotor symptoms (e.g., fatigue, desire to lie down after meals, flushing, palpitations, perspiration, tachycardia, hypotension, syncope). 
  • Late dumping syndrome usually occurs 1 to 3 hours after a meal and is a result of an incretin-driven hyperinsulinemia response after carbohydrate ingestion. Symptoms are related to neuroglycopenia (e.g., fatigue, weakness, confusion, hunger, syncope) and SNS reactivity (e.g., perspiration, palpitations, tremor, irritability).

Dietary Recommendations Following Bariatric Surgery

In order to maintain the weight loss that typically follows surgery, patients must significantly change their eating patterns. 

General advice

  • Eat balanced meals with small portions.
  • Follow a diet low in calories, fats and sweets.
  • Keep a daily record of food portions as well as calorie and protein intake.
  • Eat slowly and chew small bites of food thoroughly.
  • Avoid rice, bread, raw vegetables and fresh fruits, as well as meats that are not easily chewed, such as pork and steak. Ground meats are usually better tolerated.
  • Do not use straws, drink carbonated beverages or chew ice. They can introduce air and cause discomfort.
  • Avoid sugar, sugar-containing foods and beverages, concentrated sweets and fruit juices.
  • For the first 2 months following surgery, calorie intake should be between 300 and 600 calories a day, with a focus on thin and thicker liquids.
  • Daily caloric intake should not exceed 1,000 calories.
  • Drink extra water and low-calorie or calorie-free fluids between meals to avoid dehydration. All liquids should be caffeine-free.
  • Sip about 1 cup of fluid between each small meal, 6 to 8 times a day.
  • Avoid alcoholic beverages. 

Source: Mechanick, et al. 2019

Micronutrient Deficiencies after Bariatric Surgery

Deficiencies of micronutrients following bariatric surgery can arise from several mechanisms:

  • Preoperative deficiency
  • Reduced dietary intake
  • Malabsorption
  • Inadequate supplementation

Following surgery, all patients should start taking a multivitamin; however, there is wide variability in multivitamin formulations, and most contain inadequate amounts of minerals such as iron and calcium.

  • According to the NIH, “multivitamin” refers to any supplement containing 3 or more vitamins but no herbs, hormones or drugs, with each component at a dose less than the tolerable upper level determined by the Food and Nutrition Board—the maximum daily intake likely to pose no risk for adverse health effects

Of note, any bariatric procedure can result in malnutrition if a proper diet is not followed. Unfortunately, lack of appropriate micronutrient deficiency monitoring appears to be a gap in the long-term postoperative care for bariatric surgery patients. 

Source: Mechanick, et al. 2019

Nutrient Supplementation & Repletion After Bariatric Surgery

All patients should start micronutrient supplementation after bariatric surgery. Patients who develop symptoms suggestive of a micronutrient deficiency, or who have a micronutrient deficiency identified by screening laboratory tests, should be given appropriate repletion.

Source: Mechanick, et al. 2019

Take-Home Points!

  • Each type of bariatric surgery has advantages and disadvantages, but all require postop monitoring and dietary adherence. 
  • Micronutrient deficiencies are common before and after bariatric surgery.
  • All patients who undergo bariatric surgery should take a multivitamin, paying close attention to the formulation and contents to ensure adequate supplementation.
  • Lifelong follow-up is recommended after bariatric surgery.
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