Perioperative Nutritional, Metabolic, and Nonsurgical Support of the Bariatric Surgery Patient

Patients with the following comorbidities and BMI ≥ 35 kg/m² may also be considered for a bariatric procedure, though the strength of evidence is more variable: obesity- hypoventilation syndrome and Pickwickian syndrome after a careful evaluation of operative risk; idiopathic intracranial HTN; gastroesophageal reflux disease (GERD); severe venous stasis disease; impaired mobility due to obesity; and considerably impaired quality of life.

Notwithstanding technical surgical reasons, laparoscopic bariatric procedures should be preferred over open bariatric procedures due to lower early postoperative morbidity and mortality.

LAGB, laparoscopic sleeve gastrectomy (LSG), laparoscopic Roux-en-Y gastric bypass (LRYGB), and laparoscopic biliopancreatic diversion without/with duodenal switch (BPD/DS), or related procedures should be considered as primary bariatric and metabolic procedures performed in patients requiring weight loss and/or amelioration of ORCs.

Physicians must exercise caution when recommending BPD, BPD/DS, or related procedures because of the greater associated nutritional risks related to the increased length of bypassed small intestine.

Newer nonsurgical bariatric procedures may be considered for selected patients who are expected to benefit from short-term (i.e., about 6 months) intervention with ongoing and durable structured lifestyle with/without medical therapy.

Investigational procedures may be considered for selected patients based on available institutional review board–approved protocols, suitability for clinical targets, and individual patient factors, and only after a careful assessment balancing the importance for innovation, patient safety, and demonstrated effectiveness.

• and consider a referral to a specialist in obesity medicine.

Patients must also be provided with educational materials, which are culturally and educationally appropriate, as well as access to similar preoperative educational sessions at prospective bariatric surgery centers.

Consent should include experience of the surgeon with the specific procedure offered and whether the hospital has an accredited bariatric surgery program.

Weight loss or medical nutritional therapy may be recommended to patients in selected cases to improve comorbidities, such as glycemic targets.

Reasonable targets for preoperative glycemic control, which may be associated with shorter hospital stays and improved bariatric procedure outcomes, include a hemoglobin A1C (A1C) value of 6.5% to 7.0% (48 to 53 mmol/mol) or less and peri-procedure blood glucose levels of 80 to 180 mg/dL.

More liberal preoperative targets, such as an A1C of 7% to 8% (53 to 64 mmol/mol), are recommended in patients with advanced microvascular or macrovascular complications, extensive comorbid conditions, or long-standing diabetes in which the general goal has been difficult to attain despite intensive efforts.

In patients with A1C >8% or otherwise uncontrolled diabetes, clinical judgment determines the need and timing for a bariatric procedure.

Patients found to be hypothyroid must be treated with levothyroxine monotherapy.

Treatment should be initiated according to available and current clinical practice guidelines (CPGs) (see www.aace.com/files/ lipid-guide lines.pdf and www.lipid.org/recom mendations).

All women of reproductive age should be counseled on contraceptive choices before and after bariatric procedures.

Patients undergoing Roux-en-Y gastric bypass (RYGB) or another malabsorptive procedure should be counseled about nonoral contraceptive therapies.

Patients who become pregnant following bariatric procedure should have nutritional surveillance and laboratory screening for nutrient deficiencies every trimester, including iron, folate, vitamin B12, vitamin D, and calcium, and if after a malabsorptive procedure, fat-soluble vitamins, zinc, and copper.

Patients who become pregnant post LAGB should have band adjustments as necessary for appropriate weight gain for fetal health.

Patients with known heart disease require a formal cardiology consultation before bariatric procedures.

Patients at risk for heart disease must undergo evaluation for peri-procedure β-adrenergic blockade.

Also, tobacco use must be avoided after bariatric procedures given the increased risk of poor wound healing, anastomotic ulcer, and overall impaired health.

Structured intensive cessation programs are preferable to general advice and should be implemented.

In selecting treatment approaches to prevent thrombosis, the routine placement of a vena cava filter is discouraged. However, prophylactic placement of a vena cava filter may be considered in individual patients after careful evaluation of the risks and benefits.

The use of preoperative endoscopy may be considered in all patients being evaluated for sleeve gastrectomy (SG).

Abdominal ultrasound is indicated to evaluate symptomatic biliary disease and elevated liver function tests.

Abdominal ultrasonography or elastography may be helpful and may be considered to identify NAFLD, but may not be diagnostic.

Consideration can be made for liver biopsy at the time of a bariatric procedure to document steatohepatitis and/or cirrhosis that may otherwise be unknown due to normal appearance on imaging and/or liver function tests.

A comprehensive evaluation is recommended in those patients with clinically significant and persistent abnormal liver function tests.

Any patient considered for a bariatric procedure with a known or suspected psychiatric illness, or substance abuse or dependence, should undergo a formal mental health evaluation before the procedure.

Following RYGB and SG, high-risk groups should eliminate alcohol consumption due to impaired alcohol metabolism and risk of alcohol-use disorder postoperatively.

In comparison with purely restrictive procedures, more extensive nutritional evaluations are required for malabsorptive procedures.

Wholeblood thiamine levels may be considered in patients prior to bypass procedures (RYGB and BPD/DS).

Comprehensive preoperative optimization (prehabilitation) should be implemented, including but not limited to deep breathing exercises, continuous positive airway pressure (CPAP) as appropriate, incentive spirometry, leg exercises, continued oral nutrition with carbohydrates, including sips of clear liquids up to 2 hours preoperatively, H2 blocker or proton-pump inhibitor, opioid-sparing multimodal analgesia, thromboprophylaxis, and education about perioperative protocols.

Routine pulmonary recruitment maneuvers (PRMs) should be performed intraoperatively as needed.

Intraoperative protocols to detect possible silent bleeding sites should be performed.

Consider dynamic indicators to guide goal-directed fluid therapy to avoid excess intraoperative fluid administration.

A consultation for postoperative meal initiation and progression must be arranged with an RD who is knowledgeable about the postoperative bariatric diet.

Patients should receive education in a protocol-derived staged meal progression based on their surgical procedure.

Patients should be counseled to eat 3 small meals during the day and chew small bites of food thoroughly before swallowing.

Patients should be counseled about the principles of healthy eating, including at least 5 daily servings of fresh fruits and vegetables.

Protein intake should be individualized, assessed, and guided by an RD, regarding gender, age, and weight.

A minimal protein intake of 60 g/d and up to 1.5 g/kg ideal body weight per day should be adequate; higher amounts of protein intake—up to 2.1 g/kg ideal body weight per day—need to be assessed on an individualized basis.

Concentrated sweets should be eliminated from the diet after RYGB to minimize symptoms of the dumping syndrome, as well as after any bariatric procedure to reduce caloric intake.

Concentrated sweets should be eliminated from the diet after RYGB to minimize symptoms of the dumping syndrome, as well as after any bariatric procedure to reduce caloric intake.

Crushed or liquid rapid-release medications should be used instead of extended-release medications to maximize absorption in the immediate postprocedure period.

Minimal daily nutritional supplementation for patients with BPD/DS, RYGB, and SG should be in chewable form initially, and as 2 adult multivitamins plus minerals (each containing iron, folic acid, and thiamine),

Minimal daily nutritional supplementation for patients with LAGB should include 1 adult multivitamin plus minerals (including iron, folic acid, and thiamine),

Once patients can tolerate orals, fluids should be consumed slowly, preferably at least 30 minutes after meals to prevent GI symptoms, and in sufficient amounts to maintain adequate hydration (more than 1.5 liters daily).

In patients with severe protein malnutrition and/or hypoalbuminemia, not responsive to oral or EN protein supplementation, PN should be considered,

PN formulation for patients after bariatric procedures should be hypocaloric with relatively high nitrogen.

In immediate postoperative patients with T2D, the use of all insulin secretagogues (sulfonylureas and meglitinides), sodium-glucose cotransporter-2 inhibitors, and thiazolidinediones should be discontinued and insulin doses adjusted (due to low calorie intake) to minimize the risk for hypoglycemia.

Except for metformin and incretin-based therapies, antidiabetic medications should be withheld if there is no evidence of hyperglycemia.

Metformin and/or incretin-based therapies may be continued postoperatively in patients with T2D until prolonged clinical resolution of T2D is demonstrated by normalized glycemic targets (including fasting and postprandial blood glucose and A1C).

Subcutaneous insulin therapy, using a rapid-acting insulin analogue (insulin lispro, aspart, or glulisine) before meals and a basal long-acting insulin analogue (insulin glargine, detemir, or degludec) should be used to achieve glycemic targets (140 to 180 mg/dL) in hospitalized patients not in intensive care.

In the intensive care unit (ICU), IV regular insulin as part of a standard intensive insulin therapy protocol should be used to control hyperglycemia to a 140- to 180-mg/dL blood glucose target.

Endocrinology consultation should be considered for patients with type 1 diabetes (T1D), or with T2D and uncontrolled hyperglycemia.

Once home, in patients with T2D, periodic fasting blood glucose concentrations must be determined.

RMG determinations or the use of continuous glucose monitors is recommended if symptoms of hypoglycemia occur.

Routine admission to an ICU should not be implemented in patients solely due to the presence of severe OSA provided there is adequate CPAP use.

• as well as subcutaneously administered unfractionated heparin or low-molecular-weight heparin given within 24 hours after bariatric surgery.

Extended chemoprophylaxis after hospital discharge should be considered for high-risk patients, such as those with history of DVT, known hypercoagulable state, or limited ambulation.

The use of DVT risk calculators

• and early ambulation are encouraged.

Serum anti-Xa levels should be considered to guide low-molecular-weight heparin dosing in the prophylactic range.

Fondaparinux at 5 mg daily should be considered as a preventive option.

In the clinically stable patient, computed tomography (CT) (preferred over upper-GI studies [water-soluble contrast followed by thin barium]) may be considered to evaluate for anastomotic leaks in suspected patients.

Exploratory laparotomy or laparoscopy is justified and may therefore be considered in the setting of high clinical suspicion for anastomotic leaks.

A selected diatrizoate meglumine and diatrizoate sodium upper-GI study in the absence of abnormal signs or symptoms may be considered to identify any subclinical leaks before discharge of the patient from the hospital, but routine studies are not cost-effective.

C-reactive protein (CRP) and/or procalcitonin testing should be considered if a postoperative leak is suspected or the patient is at increased risk for a leak after hospital discharge.

When rhabdomyolysis is suspected, creatine kinase (CK) levels should be determined, urine output monitored, and adequate hydration provided.

The risk for rhabdomyolysis increases as BMI increases (particularly with BMI >55 to 60 kg/m²); therefore, screening CK levels may be tested in these higher risk groups.

Excessive postoperative IV fluids should be avoided.

Following LAGB procedures, frequent nutritional follow-up and band adjustments are recommended to optimize safety and achieve weight-loss targets.

Significant weight regain or failure to lose weight should prompt a comprehensive evaluation for:

(a) decreased patient adherence with lifestyle modification,
(b) evaluation of medications associated with weight gain or impairment of weight loss,
(c) development of maladaptive eating behaviors,
(d) psychological complications, and
(e) radiographic or endoscopic evaluation to assess pouch enlargement, anastomotic dilation, formation of a gastrogastric fistula among patients who underwent RYGB, or inadequate band restriction among patients who underwent LAGB.

Interventions should first include dietary change, physical activity, behavioral modification with frequent follow- up, and then, if appropriate, pharmacologic therapy and/or surgical revision.

In those patients with or without complete resolution of their comorbidities, such as T2D, dyslipidemia, OSA or HTN, continued surveillance and management should be guided by current CPGs for those conditions.

Routine metabolic and nutritional monitoring is recommended after all bariatric procedures.

In patients with NIPHS, therapeutic strategies should be implemented, and include dietary changes (low-carbohydrate diet), octreotide, diazoxide, acarbose, calcium- channel antagonists, gastric restriction, and/or reversal procedures, with partial or total pancreatectomy reserved for the rare recalcitrant cases.

Continuous glucose monitoring may be considered in those patients with hypoglycemia syndromes after bariatric procedures.

• self-monitoring,

• and/or mobile technologies

In patients who have undergone RYGB, BPD, or BPD/DS, treatment with oral calcium citrate and vitamin D (ergocalciferol [vitamin D2] or cholecalciferol [vitamin D3]) is indicated to prevent or minimize secondary hyperparathyroidism without inducing frank hypercalciuria.

In patients with severe vitamin D malabsorption, initial oral doses of vitamin D2 at 50,000 IU 1 to 3 times weekly or D3 (minimum of 3,000 IU/d to 6,000 IU/d) should be recommended. Of note, vitamin D3 is recommended as a more potent treatment than vitamin D2 based on frequency and amount of dosing needed for repletion; however, both can be utilized.

Recalcitrant cases may require concurrent oral administration of calcitriol (1,25-dihydroxyvitamin D).

Hypophosphatemia is usually due to vitamin D deficiency, and oral phosphate supplementation should be provided for mild to moderate hypophosphatemia (1.5 to 2.5 mg/dL).

Antiresorptive agents (bisphosphonates or denosumab) should only be considered in patients after bariatric procedures with osteoporosis once appropriate therapy for calcium and vitamin D insufficiency has been implemented.

If antiresorptive therapy is indicated after bariatric procedures, then intravenously administered bisphosphonates should be used (zoledronic acid, 5 mg once a year, or ibandronate, 3 mg every 3 months), as concerns exist about adequate oral absorption and potential anastomotic ulceration with orally administered bisphosphonates.

If concerns about absorption or potential anastomotic ulceration are obviated, oral bisphosphonate administration can be provided (alendronate, 70 mg/wk; risedronate, 35 mg/wk or 150 mg/mo; or ibandronate, 150 mg/mo). Alternatively, if bisphosphonates are poorly tolerated or ineffective, denosumab (60 mg subcutaneously every 6 months) may be considered, but again once appropriate therapy for calcium and vitamin D insufficiency has been implemented.

• a low-oxalate meal plan,

• oral calcium

• and potassium citrate therapy.

Probiotics containing Oxalobacter formigenes may be used, as they have been shown to improve renal oxalate excretion and improve supersaturation levels.

Aggressive case finding for vitamin E and K deficiencies should be reserved for those postoperative patients demonstrating symptoms (hemolytic anemia and neuromuscular, particularly ophthalmologic, for vitamin E; excessive bleeding or bruising for vitamin K).

When indicated, the dosing strategies for vitamin A are 5,000 IU/day for LAGB, 5,000 to 10,000 IU/day for RYGB and SG, and 10,000 IU/day for BPD/DS; for vitamin E, 15 mg/day for all procedures; and for vitamin K, 90 to 120 μg/d for LAGB, RYGB, and SG and up to 300 μg/d for BPD/DS.

In patients with suspected EFA deficiency in the setting of malabsorptive procedures, therapeutic trials with topical borage, soybean, or safflower oil may be considered due to the low risk profile, but these trials are unproven at present.

Iron status should be monitored in all patients within the first 3 months after bariatric procedures, then every 3 to 6 months until 12 months, and then annually thereafter for all patients.

Treatment regimens include oral ferrous sulfate, fumarate, or gluconate to provide up to 150 to 200 mg of elemental iron daily.

Vitamin C supplementation may be added simultaneously to increase iron absorption.

IV iron infusion (preferably with ferric gluconate or sucrose) may be needed for patients with severe intolerance to oral iron or refractory deficiency due to severe iron malabsorption.

More frequent aggressive case finding (e.g., every 3 months) should be performed in the first postoperative year, and then at least annually or as clinically indicated for patients who chronically use medications that exacerbate the risk of B12 deficiency: nitrous oxide, neomycin, metformin, colchicine, proton-pump inhibitors, and seizure medications.

Since serum B12 may not be adequate to identify B12 deficiency, consider measuring serum methylmalonic acid, with or without homocysteine, to identify a metabolic deficiency of B12 in symptomatic and asymptomatic patients and in patients with a history of B12 deficiency or preexisting neuropathy.

Oral supplementation (via disintegrating tablet, sublingual, or liquid) with crystalline vitamin B12 at a dosage of 350 to 1,000 μg daily or more is recommended to maintain normal vitamin B12 levels.

Intranasally administered vitamin B12 may also be considered.

Parenteral (intramuscular or subcutaneous) B12 supplementation, 1,000 μg/month to 1,000 to 3,000 μg every 6 to 12 months, is indicated if B12 sufficiency cannot be maintained using oral or intranasal routes.

• and must be supplemented further (1,000 μg/d) when a deficiency state is suspected (e.g., with skin, nail, or mucosal changes) or found, as well as in all women of childbearing age (800 to 1,000 μg/d) to reduce the risk of fetal neural tube defects.

B12 status should be assessed in patients on higher-dose folic acid supplementation (>1,000 μg/d) to detect a masked B12 deficiency state.

Routine aggressive case finding for zinc deficiency utilizing serum and plasma zinc determinations should be performed after malabsorptive bariatric surgical procedures (RYGB and BPD/DS),

• and zinc deficiency should also be considered in any patient after a bariatric procedure with chronic diarrhea, hair loss, pica, significant dysgeusia, or in male patients with unexplained hypogonadism or erectile dysfunction.

Treatment of zinc deficiency should target normal biochemical levels with 1 mg/d of copper also supplemented for every 8 to 15 mg/d of elemental zinc provided.

• but especially in patients who are experiencing anemia, neutropenia, myeloneuropathy, or impaired wound healing.

Copper supplementation (2 mg/d) should be included as part of a routine multivitamin-multimineral preparation; further supplementation varies depending on the surgical procedure performed, with greater amounts required for patients who have had RYGB or BPD/ DS.

In severe deficiency, treatment can be initiated with IV copper (3 to 4 mg/d) for 6 days.

Subsequent treatment of severe deficiency, or treatment of mild-to-moderate deficiency, can usually be achieved with 3 to 8 mg/day of oral copper sulfate or gluconate until levels normalize and symptoms resolve.

Patients being treated for zinc deficiency or using supplemental zinc for hair loss should receive 1 mg of copper for each 8 to 15 mg of elemental zinc, since zinc replacement can cause copper deficiency.

Copper gluconate or sulfate is the recommended source of copper for supplementation.

Routine thiamine screening may be considered following bariatric procedures.

Aggressive case finding for thiamine deficiency and/or empiric thiamine supplementation is indicated for high-risk postprocedure patients, such as those with established preprocedure risk factors for thiamine deficiency, females, African Americans, patients not attending a nutritional clinic, patients with GI symptoms, patients with heart failure, protracted vomiting, PN, excessive alcohol use, neuropathy or encephalopathy

• or small intestinal bacterial overgrowth (SIBO).

All post-WLS patients should take at least 12 mg of thiamine daily.

A 50- to 100-mg daily dose of thiamine from a B-complex supplement or high-potency multivitamin may be needed to maintain sufficient blood levels of thiamine and prevent thiamine deficiency in some patients.

Patients with severe thiamine deficiency (suspected or established) should be treated with IV (or intramuscular if IV access is not available) thiamine, 500 mg/d, for 3 to 5 days, followed by 250 mg/d for 3 to 5 days or until resolution of symptoms, and then to consider treatment with 100 mg/d, orally, usually indefinitely or until risk factors have resolved.

Mild deficiency can be treated with IV thiamine, 100 mg/d, for 7 to 14 days.

In patients with recalcitrant or recurrent thiamine deficiency with one of the above risks, the addition of antibiotics for SIBO should be considered.

The effect of weight loss on dyslipidemia is variable and incomplete; therefore, lipid-lowering medications should not be stopped unless clearly indicated.

Because the effect of weight loss on blood pressure is variable, incomplete, and at times transient, antihypertensive medications should not be stopped unless clearly indicated; however, dosages may need to be titrated downward as blood pressure improves.

Patients with T2D who had their diabetes medication stopped after bariatric procedures must be monitored closely for recurrence of hyperglycemia, particularly with weight regain or suboptimal weight loss.

Oral liquid forms of levothyroxine may be considered in those patients who have difficulty swallowing tablets after bariatric procedures.

Oral liquid or softgel forms of levothyroxine may be considered in patients with significant malabsorption in whom adequate TSH suppression to normal ranges is difficult after bariatric procedures.

Upper endoscopy with small-bowel biopsies and aspirates remains the gold standard and should be part of the evaluation of celiac disease and bacterial overgrowth in patients who have had a bariatric procedure.

Screening with a stool specimen should be obtained if the presence of Clostridium difficile colitis is suspected.

Persistent steatorrhea after BPD without/with DS should prompt evaluation for nutrient deficiencies.

Ideally, alternative pain medication should be identified before the bariatric procedure.

If the use of NSAIDs is unavoidable, then the use of proton-pump inhibitors may be considered.

Endoscopy may also be used for Helicobacter pylori testing as a possible contributor to persistent GI symptoms after bariatric procedures.

H2 receptor blockers and sucralfate may also be considered for postprocedure anastomotic ulcers, and if Helicobacter pylori is identified, triple therapy, including antibiotics, bismuth, and proton-pump inhibitors, may be used.

Persistent symptoms of gastroesophageal reflux, regurgitation, chronic cough, or recurrent aspiration pneumonia in a patient after LAGB raise concern for band slippage, esophageal dilation, and, in some cases, erosion, and should prompt evaluation of the patient with upper-GI endoscopy or fluoroscopy,

• immediate referral to a bariatric surgeon, and depending on the clinical course, consideration of conversion to SG or RYGB.

Patients who undergo SG, RYGB, or BPD/DS are at increased risk for cholelithiasis due to rapid weight loss, and oral administration of ursodeoxycholic acid is recommended: 500 mg once daily for SG and 300 mg twice a day for RYGB or BPD/DS.

In asymptomatic patients with known gallstones and a history of RYGB or BPD/DS, prophylactic cholecystectomy may be considered to avoid choledocholithiasis, since traditional endoscopic retrograde cholangiopancreatography can no longer be performed in these patients. Otherwise, cholecystectomy should be reserved for patients with symptomatic biliary disease due to a generally low incidence of biliary complications.

For antibiotic-resistant cases of bacterial overgrowth, probiotic therapy with Lactobacillus plantarum 299v and/or Lactobacillus GG may be considered.

Thiamine deficiency may be suspected in patients with SIBO after bariatric procedures, especially when gut dysmotility occurs.

Symptomatic hernias that occur after bariatric surgery may require prompt surgical evaluation.

Patients with sudden-onset of severe cramping, periumbilical pain, or recurrent episodes of severe abdominal pain any time after bariatric surgery should be evaluated with an abdominal and pelvic CT scan to exclude the potentially life-threatening complication of a closed-loop bowel obstruction.

Exploratory laparotomy or laparoscopy is indicated in patients who are suspected of having an internal hernia because this complication can be missed with upper-GI x-ray studies and CT scans.

Body-contouring surgery is best pursued after weight loss has stabilized (12 to 18 months after bariatric surgery).

The initiation and formulation of EN (tube feeding) or PN should be guided by current CPGs.

Hospital admission is required for the management of GI complications after bariatric procedures in clinically unstable patients.

Surgical management should be pursued for GI complications not amenable or responsive to medical therapy.

However, if not dehydrated, patients may undergo endoscopic stomal dilation for stricture as an outpatient procedure.