Nutrition And Bariatric Surgery

From the 15th Annual Medical and Surgical Approaches to GI Disorders, presented by the Medical College of Georgia

Educational Objectives

The goals of this program are to improve management of enteral nutrition in critically ill patients and to improve management of complications of bariatric surgery. After hearing and assimilating this program, the clinician will be better able to:

1.   Identify patients to whom the nutritional guidelines developed by the Society of Critical Care Medicine (SCCM) and American Society for Parenteral and Enteral Nutrition (ASPEN) should be applied.

2.   Prescribe appropriate enteral nutrition formulations for critically ill surgical patients.

3.   Enumerate the risks associated with bariatric surgery.

4.   Prevent the development of nutritional deficiencies in patients who have undergone bariatric surgery.

5.   Recognize and manage the most common complications of bariatric surgery.

Faculty Disclosure

In adherence to ACCME Standards for Commercial Support, Audio-Digest requires all faculty and members of the plan­ning committee to disclose relevant financial relationships within the past 12 months that might create any personal con­flicts of interest. Any identified conflicts were resolved to ensure that this educational activity promotes quality in health care and not a proprietary business or commercial interest. For this program, the faculty and planning committee reported nothing to disclose.

Acknowledgements

Drs. Cresci and Martindale were recorded at Fifteenth Annual Medical and Surgical Approaches to GI Disorders, held July 19-23, 2010, on Kiawah Island, GA, and sponsored by the Medical College of Georgia. The Audio-Digest Foundation thanks the speakers and the Medical College of Georgia for their cooperation in the production of this program.

Enteral Feeding for the Critically Ill Patient

Gail Cresci, PhD, RD, Assistant Professor of Surgery and Director, Surgical Nutrition Service, Medical College of Georgia, Augusta

Guidelines for nutritional support of critically ill adult patient: developed by Society of Critical Care Medicine (SCCM) and American Society for Parenteral and Enteral Nutrition (ASPEN); intended for adult medical and sur­gical patients in intensive care unit (ICU) >3 days; should be adapted to individual patients

Target patients: usually in catabolic state; often have systemic inflammatory response, infectious complications, multiple organ dysfunction, prolonged hospitalization, and disproportionately high mortality

Nutrition support: therapeutic aims include attenuation of metabolic response to stress, prevention of oxidative cel­lular injury, and favorable modulation of immune process; therapeutic approaches include early enteral feeding, appropriate nutrient delivery, and meticulous glycemic control

SCCM-ASPEN guidelines: enteral nutrition (EN) indicated for critically ill patient who cannot maintain volitional intake; rationale  —  EN helps maintain functional and structural integrity of gut; preferred over parenteral nutri­tion (PN) whenever possible

Benefits of EN over PN: no differential effect on mortality; reduction in infectious morbidities (eg, pneumonia, in­fections of bloodstream); reduced length of hospital stay and associated costs

Timing: begin EN within 24 to 48 hr of admission to ICU; progress to patient’s goal nutritional needs within 48 to 72 hr; rationale  —  EN started soon after metabolic insult associated with less gut permeability, diminished acti­vation and release of inflammatory cytokines, and reduced systemic endotoxemia

Hemodynamically compromised patients: use EN cautiously; at height of critical illness, patients prone to gut dys­motility, sepsis, and hypotension; at risk for subclinical ischemia and reperfusion injury involving intestinal mi­crocirculation; ischemic bowel rare complication of EN

Mechanisms of gut ischemia: impaired oxygen delivery to gastrointestinal (GI) tract; short-circuiting of oxygen within countercurrent exchanger of GI tract microvilli; increased oxygen demand of enteral feeding during hy­potensive state (disproportionate vasoconstriction occurs in response to stress; feeding increases oxygen de­mand in gut mucosa; without adequate oxygen, ischemia and necrosis of bowel may develop)

Recommendations for hypotensive patient: do not feed enterally if initiating blood pressure support in ICU, or in­creasing vasopressor dose or adding second or third vasopressor; can initiate enteral feeding if patient currently on vasopressors, stable for 24 to 48 hr, and enteral access available; start with 10 mL/hr and monitor patient; ensure patient adequately resuscitated; formula should not contain fiber (may obstruct GI tract); watch for signs of intolerance of EN feeding and suspend if necessary; indications for suspending feeding  —  new abdominal pain or increased abdominal distension, cessation of flatus or stool, or development of metabolic acidosis or base deficit

Calories: provide at least 50% to 65% of goal calories, increasing to goal if possible; ensure adequate protein intake if patient has body mass index (BMI) <30 (1.2-2.0 g protein/kg actual body weight); permissive hypocaloric feeding  —  for patients with BMI >30; provide 60% to 70% of patient’s target energy requirements, while meeting protein requirements; if BMI 30 to 40, protein allowance should be >2 g/kg ideal body weight; if BMI >40, pro­vide ³2.5 mg/kg ideal body weight

Enteral formulations: only immune-modulating formulas well studied; contain arginine, glutamine, nucleic acids, omega-3 fatty acids, and antioxidants to improve immune function; rationale  —  immune-modulating nutrients associated with decreased time on mechanical ventilation, less infectious morbidity, and shorter length of stay (among patients who meet selection criteria)

Patients most likely to benefit: individuals undergoing major surgery (particularly of GI tract), critically ill patients on mechanical ventilation, and trauma patients

Lipids: a-linolenic acid (omega-3 fatty acid) and linoleic acid (omega-6 fatty acid); share enzyme systems in body; produce prostaglandins, leukotrienes, and thromboxanes; omega-3 fatty acids reduce inflammation and appear to be vasodilatory; in large quantities, omega-6 fatty acids proinflammatory and vasoconstrictive; en­teral formulas targeted to inflammatory states now supplemented with omega-3 fatty acids and antioxidants

Calorically dense formulas: volume-restricted; consider for patients with acute respiratory failure; rationale  —  fluid accumulation associated with pulmonary edema and poor clinical outcomes; restricting volume while pro­viding calories may be beneficial

Other types of formulas: with fiber  —  may help patients with diarrhea not related to hyperosmolarity of solution or infection; avoid in hypotensive patients; predigested (small peptide) formulas  —  data supporting use scarce

Renal formulas: guidelines recommend that patients with acute renal failure or injury be placed on standard for­mula; use renal formula only if electrolyte abnormalities develop; rationale  —  dialysis stimulates heat loss and stress response; patients lose electrolytes and amino acids; Kidney Disease Outcomes Quality Initiative recom­mends 1.4 to 1.8 g protein/kg body weight, or £2.5 g/kg to maintain nitrogen balance; switch to high-protein for­mula if necessary

Diabetic formulas: ICU should have glycemic control protocol in place; maintain patient’s blood glucose between 110 and 150 mg/dL; no data support use of diabetic formulas specifically (insulin therapy recommended for gly­cemic control; carbohydrates should supply »50% of calories)

Pulmonary formulas: no recommendation for ICU patients; avoid overfeeding and rapid infusion of fat emulsions if providing PN

Hepatic formulas: no data support use; patients with liver failure hypercatabolic; most are malnourished (require more nutrition than provided by formula); reserve formulas for rare encephalopathic patient refractory to stan­dard treatment with luminal acting antibiotics and lactulose

Managing Nutritional and Metabolic Complications of Bariatric Surgery

Robert G. Martindale, MD, PhD, Professor and Chief, Division of General Surgery, Oregon Health and Sci­ence University, Portland

Indications for bariatric surgery: BMI >40, or >35 with comorbidities; »21 million Americans meet criteria; in United States, incidence of adolescent diabetes has increased 10-fold over past 10 yr; diabetic complications de­velop over 15 to 30 yr (ie, complications will start occurring in people 30-40 yr of age); »217,000 bariatric surgery procedures performed in 2009 (up from 47,000 in 2001); gastric bypass comprised 65% of procedures in 2009; lap band comprised 20% (use increasing); sleeve gastrectomy comprised 10% (also gaining favor; easy to perform); duodenal switch <5%

Current procedures

Sleeve gastrectomy: greater curvature of stomach stapled off; associated with good weight loss; developed for pa­tients whose weight contraindicated gastric bypass

Roux-en-Y gastric bypass: most common procedure; reduces pouch capacity to 15 mL

Biliopancreatic or duodenal switch: popularity fading; leaves stomach intact so patients can eat what they want; as­sociated with extensive weight loss due to significant malabsorptive component

Restrictive operations (eg, gastric band): not effective

Other types of procedures: endoscopic gastric partitioning; ileum interposition; intragastric balloons; gastric wrap­ping; gastric pacing (no benefit found); deep brain stimulation (works well, but difficult to obtain approval from insurers); wiring of jaw; injections of botulinum toxin (ineffective)

Effects of bariatric surgery: reverses type 2 diabetes; most consistent treatment of obesity; complications “grossly underreported”; Longitudinal Assessment of Bariatric Surgery (LABS) project  —  funded by National Institutes of Health; currently in phase II; 89% of patients followed for 7.5 to 10 yr; data suggest that risks higher and patient compliance lower than reported in single-institution studies; 1-yr mortality rate 5% in high-risk patients; other studies end follow-up at 30 days; in LABS report, mortality risk factors included advanced age, male sex, and surgeon experience; training curve  —  80 to 100 cases

Complications: mortality; leaks (0%-3% of cases; 10% of deaths occur ³1 yr after surgery); metabolic complica­tions; type of operation and when performed influence risk for complications; 15% of patients develop nutri­tional deficiencies preoperatively (preoperative nutritional testing recommended); patients’ food preferences change after surgery; postoperative deficiencies depend largely on type of procedure performed due to differ­ences in size and type of remaining absorptive surface; patients should take supplements of vitamin B₁₂, folate, and fat-soluble vitamins; weight loss should not exceed 1 lb/wk beyond first 6 wk after surgery

Protein-calorie malnutrition: occurs in 26% of patients undergoing biliopancreatic switch (common channel 50 cm long; associated with rapid weight loss, but may require reversal if complications become severe); also oc­curs in »1% of patients with common channel >200 cm; patient may require short course of EN feeding to achieve adequate repletion of protein before reversal surgery; iron deficiency most common nutrient deficiency after bariatric surgery

Vitamin and mineral deficiencies: exacerbated by pregnancy after surgery in patients who cease taking supple­ments; folate deficiency associated with fetal neural tube defects; relatively common reason for litigation after bariatric surgery; deficiencies of all fat soluble vitamins also common in patients with malabsorptive proce­dures; >50% of patients undergoing biliopancreatic switch will develop vitamin D deficiency due to malab­sorption (need huge replacement doses [35,000 to 50,000 IU/day for several weeks, followed by maintenance dose of 25,000 IU] to prevent metabolic bone disease)

Management of metabolic bone disease: increase patient’s intake of calcium; supplement ergocalciferol and cal­citriol; intramuscular or transdermal vitamin D

Vitamin B₁₂ deficiency: relatively rare; daily dose 1 to 3 µg if patient has intrinsic factor; bariatric supplements contain 500 µg (patients who lack intrinsic factor absorb 1% passively

Vitamin B₁ (thiamine) deficiency: can develop due to persistent nausea and vomiting; if serious, may lead to Wer­nicke encephalopathy; characterized by ataxia, visual changes, and global confusion; failure to recognize may be grounds for lawsuit; diagnose by measuring serum erythrocyte transketolase levels

Classic emergency complaints: abdominal pain, vomiting, fever, melena or hematochezia, and hematemesis most common; ask if patient has had symptoms before or any other complications

Possible diagnoses: recent surgery (within 5-7 days)  —  leak most likely; surgery >30 days ago  —  possible obstruc­tion; after adjustable band surgery  —  pain usually associated with slipped gastric band; low pain after gastric bypass  —  leak may be at Roux-en-Y connection (patient may also complain of pelvic pressure); severe unrelent­ing pain  —  surgery indicated

Intra-abdominal complications: if pain generalized and persistent, rule out hernia (surgery likely needed; cannot be repaired endoscopically); white foamy vomit suggests overeating; vomiting of recently ingested food suggests stomal stenosis, proximal Roux-en-Y obstruction, or (most commonly) repetitive dietary indiscretions; persis­tent vomiting of large quantities of darker fluid suggests low torsion or obstruction; fever in patient with recent gastric bypass or gastric sleeve suggests leak; persistent unexplained tachycardia most common presenting symptom of leak

Potential leak sources: pouch; staple line of excluded stomach; jejunojejunostomy; gastrojejunostomy leaks com­mon (usually require repeat surgery); pouch leaks also require surgery; insert drain to manage leak at excluded stomach; leak at jejunojejunostomy requires surgery; pain occurs in lower pelvis; diagnosing leaks  —  perform water contrast computed tomography (upper GI series unreliable in morbidly obese patients); assess patient’s overall clinical condition; percutaneous drainage possible in some cases, but most will require surgery

Other complications: stomal obstruction of gastrojejunostomy or jejunojejunostomy (usually presents as pain and cramps; obstruction of biliary limb sometimes associated with jaundice as well as severe cramping pain); internal hernia through small bowel mesentery or Petersen’s space (behind Roux-en-Y); obstruction of transverse colon; bleeding at staple line  —  if soon after surgery, return to operating room; if in excluded stomach, appears as bright red blood per rectum 3 to 7 days postoperatively; usually requires reoperation; bleeding at jejunojejunostomy usually presents as melena or hematochezia within 24 hr of surgery (usually requires suturing, but trial of treat­ment with thrombin slurry may be attempted first; suture under endoscopic guidance); emergent cases  —  stomal obstruction; band slippage (causes torsion of stomach and gastric necrosis); high-grade bowel obstruction; inter­nal hernias; leaks; bleeding

Conclusion: “surgery not the answer”; average body weight in United States decreased for last 2 yr; education is key

Suggested Reading

Beedupalli J: Bariatric surgery and mortality. N Engl J Med 2007 Dec 20;357(25):2633; Bell L: Early enteral nutrition in critically ill patients. Am J Crit Care 2010 May;19(3):269; Blackburn GL et al: Nutrition support in the intensive care unit: an evolving science. Arch Surg 2010 Jun;145(6):533-6; Deveney CW, Martindale RG: Factors in selecting the optimal bariatric procedure for a specific patient and parameters by which to measure appropriate response to surgery. Curr Gastro­enterol Rep 2010 Aug;12(4):296-303; Elder KA, Wolfe BM: Bariatric surgery: a review of procedures and outcomes. Gas­troenterology 2007 May;132(6):2253-71; Longitudinal Assesment of Bariatric Surgery (LABS) Consortium: Perioperative safety in the longitudinal assessment of bariatric surgery. N Engl J Med 2009 Jul 30;361(5):445-54; Martin JM, Stapleton RD: Omega-3 fatty acids in critical illness. Nutr Rev 2010 Sep;68(9):531-41; Martindale RG et al: Guide­lines for the provision and assessment of nutrition support therapy in the adult critically ill patient: Society of Critical Care Medicine and American Society for Parenteral and Enteral Nutrition: Executive Summary. Crit Care Med 2009 May;37(5):1757-61; McClave SA et al: Guidelines for the Provision and Assessment of Nutrition Support Therapy in the Adult Critically Ill Patient: Society of Critical Care Medicine (SCCM) and American Society for Parenteral and Enteral Nu­trition (ASPEN). JPEN J Parenter Enteral Nutr 2009 May-Jun;33(3):277-316; Wolfe B: Bariatric surgery: an evolving field. World J Surg 2009 Oct;33(10):1981-2; Wolfe BM, Morton JM: Weighing in on bariatric surgery: procedure use, re­admission rates, and mortality. JAMA 2005 Oct 19;294(15):1960-3.