December 2015 Issue
Short Bowel Syndrome in Adult PN Patients - Today's Dietitian Magazine
By Mandy L. Corrigan, MPH, RD, CNSC, FAND
Today's Dietitian
Vol. 17 No. 12 P. 30
Short bowel syndrome is a complex condition affecting the GI tract. Learn more about its pathophysiology and treatment and management strategies to improve patient care.
Caring for adult parenteral nutrition (PN) patients who have various disease states often is challenging for the clinical dietitian. One disease that's particularly complex when it comes to treatment and management is short bowel syndrome (SBS).
SBS is characterized by malabsorption of nutrients, fluids, and electrolytes following intestinal resections or damage to the functional capacity of the intestine. Because the anatomy of SBS patients varies widely, the heterogeneity of this population doesn't lend itself well to the completion of large prospective randomized trials. Most of the scientific knowledge of nutritional management of SBS comes from best practices based on trials completed with small groups of patients. Nutritional, medical, and surgical interventions to treat SBS depend on patients' individual needs and therefore bring unique challenges for clinicians.1
Fluids, electrolytes, micronutrients, oral diet modifications, medications to manage bowel motility, and PN management are areas dietitians can address in accordance with a nutrition care plan for SBS patients. It's imperative to assess nutrients provided by the enteral (oral or enteral tube feeding) and parenteral routes. "Eating food has important benefits for quality of life, even for HPN [home parenteral nutrition]-dependent patients with short bowel syndrome," says Marion Winkler, PhD, RD, CNSC, surgical nutrition specialist at Rhode Island Hospital. "Dietitians can help patients address four important roles of food, although not every patient will eat for the same reasons. These include socialization (eating for taste, pleasure, comfort, and belonging), health benefits and immune enhancement, gastrointestinal (GI)-symptom management (although diarrhea often has no rhyme or reason), and energy and nutrient contribution (especially if receiving supplemental PN). I always recommend that my patients eat small meals frequently throughout the day and chew, chew, chew and sip, sip, sip."
This article will provide a brief overview of the pathophysiology of SBS and practical nutrition treatment strategies for clinicians managing adult patients.
Population Impact
While the Crohn's and Colitis Foundation of America estimates that 10,000 to 20,000 adult patients in the United States have SBS, more accurate incidence and prevalence data remain relatively unknown. There is no US patient database for SBS, and it would be difficult to determine these figures based on PN registries from international countries since the incidence and prevalence vary widely by country and region.
Defining SBS
SBS is characterized by malabsorption due to either surgical resection or functional loss of the small intestine in which the length remains but the bowel functions abnormally. These factors prevent normal absorption of fluid, micronutrients, macronutrients, and electrolytes.1,2 The length of small bowel that remains often defines the severity of SBS, but this is only a small piece of the puzzle because the quality of the remaining anatomy plays an important role.
Most SBS patients will require the use of PN in the immediate postoperative phase after a large intestinal resection; however, not all patients will require lifelong PN support. The potential for regaining nutritional autonomy via the enteral route depends on the amount, location, and quality of the remaining small bowel, as well as the presence or absence of the ileocecal valve and the colon. It's imperative to understand what has been surgically resected and the current anatomy that remains to direct the nutrition care plan. In general, patients with at least 100 to 150 cm of functional small bowel without a colon or 60 to 90 cm with a fully functional colon in continuity can be successfully weaned from PN.2,3 In the two years following resection, the bowel is in an adaptation phase.
Types of Intestinal Resection and Nutritional Consequences
Common features of SBS are rapid transit of intestinal contents through the intestinal tract and malabsorption of micro- and macronutrients due to the loss of surface area. The type of resection provides clues to the nutrition challenges patients will encounter.
Jejunal ileal resections (in which a portion of the jejunum and some ileum are resected and the remaining portions are in continuity with the colon) generally are well tolerated. This type of resection preserves the ileocecal valve (responsible for preventing the reflux of bacteria between the ileum and colon and regulating motility); vitamin B12 production is maintained, and the ileum can adapt to assume some of the functions of the jejunum that was resected. In general, patients with a jejunal ileal resection do better from an absorption standpoint compared with other types of intestinal resections.3,4 With jejunal resections, gastric acid hypersecretion may be problematic (which will be discussed more in the following section). Retaining the colon also lends itself to enhanced fluid and calorie absorption.
Large ileal resections leading to jejunum anastomosed to the colon is more problematic compared with jejunal ileal resections. These patients often will require supplemental vitamin B12, have bile salt malabsorption, fat soluble vitamin malabsorption, potential for small bowel bacterial overgrowth due to loss of the ileocecal valve, and higher fluid losses due to rapid intestinal transit.
Patients with a jejunostomy (no colon in continuity) are most challenging to manage since the jejunum can't adapt to take on the functions of the lost portion of the ileum. SBS patients with a jejunostomy have high-volume fluid and electrolyte losses, micronutrient deficiencies (especially zinc and copper), and rapid intestinal transit leading to malabsorption. Often, these patients will require high-volume PN solutions and are most likely to require parenteral support long-term.
Treatment and Management Challenges
Not only are patients with SBS plagued by rapid transit of intestinal contents through the GI tract, they often experience gastric acid hypersecretion, fluid and electrolyte abnormalities, weight loss due to malabsorption of macronutrients, and bacterial overgrowth, and they require diet modifications.5 An interdisciplinary team approach to managing these patients can address all facets of the nutrition, medical, and surgical care plan to maximize intestinal adaptation, prevent complications, and preserve quality of life. "Parenteral nutrition management of patients with short bowel syndrome can be done safely and effectively by routinely monitoring clinical and laboratory parameters in close cooperation with the patient, PN solution supplier, and the patient's medical team," says Ezra Steiger, MD, FACS, FASPEN, a professor of surgery at the Cleveland Clinic in Ohio.
Gastric Acid Hypersecretion
Following a large intestinal resection, especially a large jejunal surface area loss, the mechanism that controls gastric acid production is compromised. This can continue for roughly six months postoperatively and lead to several problems. First, the volume of gastric secretions increases, pushing a higher volume of secretions into the GI tract. Second, the high acid content alters the pH of the intestinal tract and can denature the pancreatic sections that are composed of pancreatic enzymes and bicarbonate, which enter the duodenum. As a result, it's prudent for dietitians to ensure patients are receiving either a histamine2-receptor antagonist or proton pump inhibitor, both of which decrease gastric acid production.5
Fluid Challenges
Patients with an enterostomy, jejunostomy, or ileostomy have higher fluid requirements compared with patients who have a colon in continuity. Having at least one-half of the colon is equivalent to having an additional functionality of 50 cm of small bowel. The improved fluid and sodium absorption due to having a colon in continuity enables the colon to ferment undigested carbohydrates into short chain fatty acids for additional energy absorption,3,5 which can be a valuable source of calories for patients with malabsorption.
Moreover, patients with SBS may develop physical signs and symptoms of dehydration well before changes in biochemical studies are seen.6 RDs can look at the volume of urine patients produce (the goal is a minimum of 1,200 mL/day) to guide oral or IV fluid delivery, and monitor vital signs and physical symptoms. Signs of dehydration may include dizziness or lightheadedness, dark or concentrated urine, dry mucous membranes, excessive thirst, and sunken eyes.
Often, patients with SBS experience a high volume of GI fluid losses, and their natural reaction is to consume more fluid in response to thirst sensations. However, consuming more fluid can lead to greater fluid losses and worsen dehydration. IV fluids and PN solutions, which aren't associated with malabsorption, can improve and maintain hydration status in SBS patients. RDs must educate patients about diet modifications that will reduce fluid losses, encourage them to monitor their fluid balance, and ensure they learn to recognize signs and symptoms of dehydration. Patients can sip oral rehydration solutions throughout the day, although they should limit hypertonic beverages, as these also may lead to excess fluid losses via the GI tract.5
Electrolyte Challenges
Fluid losses often are coupled with electrolyte losses. Frequent electrolyte imbalances seen in patients with SBS come from great losses of sodium, potassium, magnesium, bicarbonate, and chloride from the GI tract. Tables that quantify electrolyte content of various types of GI losses have been published in the literature.5,7 When making adjustments to electrolytes within PN solutions, RDs can evaluate serum electrolyte levels, calculate approximate additional electrolyte requirements based on the type of anatomy and volume of GI losses (eg, from tables that provide approximate electrolyte content of GI secretions), and assess IV electrolyte infusions provided apart from PN solutions. It's important to remember that as GI losses and malabsorption are better controlled with dietary modifications and medications, electrolyte losses may not be as severe and PN solutions may need adjustments to prevent excessive serum electrolyte values. Electrolytes are best repleted and maintained when delivered through the IV route. Oral or liquid electrolyte delivery via the enteral route is plagued by malabsorption in SBS patients and leads to inconsistent serum levels. When RDs observe electrolyte imbalances, it's critical to inquire about any physical symptoms associated with that electrolyte during the patient interview.
Oral Diet Modifications
While making dietary modifications, it's important to remember that digestion starts in the mouth with the help of the enzymes lingual lipase and salivary amylase. In addition, chewing food thoroughly is essential to preparing the food for the lower GI tract. The prescribed diet for patients with SBS comprises eating small amounts of food frequently throughout the day (eg, three small meals and three snacks), separating foods from liquids, sipping liquids slowly throughout the day, avoiding simple sugars or concentrated sweets as well as salty and starchy foods. This pattern of eating allows for optimal absorption of nutrients. Patients with an enterostomy can consume a diet with a fat content of 30% to 40% of total calories, whereas patients with a colon in continuity fare better following a diet with a fat content of 20% to 30% of total calories and a carbohydrate content of 50% to 60% of total calories.2,8 Overall, RDs should encourage polyphagia (ie, patients should eat nutrient-dense foods that are higher in calories than expected to meet energy needs), to offset some of the malabsorption these patients experience.
Long-Term PN Considerations and Social Support
Managing patients on short-term PN infusions in a hospital is much different from managing patients requiring long-term PN in the home setting. Maintaining quality of life is an important goal for patients requiring PN and long-term diet modifications due to SBS.
Clinical considerations related to schedules and equipment modifications can enhance PN delivery in the home setting. Cycled infusions are used in place of continuous around the clock PN infusions. Patients on home PN often are mobile. They carry portable-sized ambulatory pumps in backpacks that allow for more movement during cycled infusions.5 RDs can counsel and encourage patients, and support long-term nutrition modifications with continuous reinforcement.
Long-term patients often benefit from support not only from family, friends, and caregivers, but organizations such as the Oley Foundation and the SBS Foundation that offer education and advocacy to SBS patients and those receiving enteral nutrition or PN outside the hospital setting. RDs can refer patients to organizations such as these to connect with others who have similar conditions.
Infection Prevention
Another consideration is the risk of blood stream infections in patients who use a central venous catheter for PN delivery. Prevention is key, so it's important for RDs to encourage patients to practice good hand hygiene. Hand hygiene and the aseptic technique are important to practice when patients are preparing to hook up PN solutions, priming tubing, adding additives to the PN bag, or providing routine line care, which involves changing the end cap, dressing, and skin/catheter site care. Patients with SBS are prone to experiencing a large volume of stool losses, so it's imperative to keep the end of the central venous catheter from coming in contact with stool and away from enterostomy bags. Encouraging patients to practice good hand hygiene may seem simple, but continued reminders and education can play a role in prevention.9
Optimal Patient Care Is Possible
Caring for patients with SBS can be challenging medically and nutritionally. However, dietitians who develop an in-depth understanding of SBS, its nutritional consequences, and the treatment and management challenges associated with it, and who work with an interdisciplinary team will be well equipped to care for SBS patients, promote positive outcomes, and preserve quality of life.
— Mandy L. Corrigan, MPH, RD, CNSC, FAND, is a nutrition support clinician and consultant in St. Louis.
References
1. Jeppesen PB. Spectrum of short bowel syndrome in adults: intestinal insufficiency to intestinal failure. JPEN J Parenter Enteral Nutr. 2014;38(Suppl 1):8S-13S.
2. Matarese LE. Short bowel syndrome. In: Mullin GE, Matarese LE, Palmer M, eds. Gastrointestinal and Liver Disease Nutrition Desk Reference. Boca Raton, FL: CRC Press; 2012:35-50.
3. Messing B, Crenn P, Beau P, Boutron-Ruault MC, Rambaud JC, Matuchansky C. Long-term survival and parenteral nutrition dependence in adult patients with short bowel syndrome. Gastroenterology. 1999;117(5):1043-1050.
4. Tappenden KA. Pathophysiology of short bowel syndrome: considerations of resected and residual anatomy. JPEN J Parenter Enteral Nutr. 2014;38(Suppl 1):14S-22S.
5. Parrish CR. The clinician's guide to short bowel syndrome. Pract Gastroenterol. 2005;31(9):67-106.
6. Konrad D, Corrigan ML, Hamilton C, Steiger E, Kirby DF. Identification and early treatment of dehydration in home parenteral nutrition and home intravenous fluid patients prevents hospital admissions. Nutr Clin Pract. 2012;27(6):802-807.
7. Whitmire SJ. Fluid, electrolytes, and acid-base balance. In: Matarese LE, Gottschlich MM, eds. Contemporary Nutrition Support Practice: A Clinical Guide. 2nd ed. Philadelphia, PA: Saunders Elsevier; 2003:127-144.
8. Nordgaard I, Hansen BS, Mortensen PB. Colon as a digestive organ in patients with short bowel. Lancet. 1994;343(8894):373-376.
9. John BK, Khan MA, Speerhas R, et al. Ethanol lock therapy in reducing catheter-related bloodstream infection in adult home parenteral nutrition patients: results of a retrospective study. JPEN J Parenter Enteral Nutr. 2012;36(5):603-610.
TOOLBOX FOR CLINICAL RDS
Consider the following six factors and the management strategies under each when caring for patients with short bowel syndrome (SBS) who are receiving parenteral nutrition (PN).
1. Anatomy
• No two SBS patients are exactly alike, so it's important for clinical dietitians to learn all they can about the individual needs of patients. Determine what part of the small or large bowel has been resected, whether the ileocecal valve remains, and if the patient has a colon in continuity with the small intestine. In addition, establish the length/functional quality of the remaining small bowel.
• Know where vitamins, minerals, and electrolytes are absorbed to anticipate what deficiencies patients may have if a certain area of the bowel is surgically absent.
• Learn the anatomy of the gastrointestinal (GI) tract to facilitate evaluating which diet modifications patients may benefit from and prevent unnecessary dietary restrictions.
2. Fluids
• Monitor fluid status closely and evaluate for physical signs of dehydration such as dizziness, lightheadedness, decreased urine output, darker color urine, excessive thirst, dry mucous membranes, and sunken eyes, and correlate to blood chemistries. In addition, look for high-volume GI losses.
• Set a goal for the patient to produce at least 1,200 mL of urine daily.
• PN or use of IV fluids guarantees hydration, whereas oral fluids may worsen dehydration. If the patient continues to drink, additional fluid loss via the GI tract may result.
• Encourage patients to sip oral rehydration solutions (ORS) slowly throughout the day. ORS activate the sodium glucose co-transport system and turn on a mechanism enabling the bowel to absorb fluid.
• Compliance with ORS can be challenging because of the taste; however, patients often report improvements in hydration with their use and by eliminating plain water and hypertonic beverages (ie, simple sugar beverages).
3. Medication Review
• If an SBS patient has undergone a major jejunal resection, check to make sure they're receiving a histamine2-receptor antagonist or proton pump inhibitor to combat gastric acid hypersecretion.
• Evaluate a patient's medication list for antidiarrheal agents (eg, Imodium, diphenoxylate-atropine, codeine, tincture of opium) and antisecretory agents (eg, octreotide, clonidine). It's important to know what medications are being prescribed at what dosage, and the time they've given.
• Schedule the administration of antidiarrheal medications 30 to 60 minutes before meals instead of after meals or on an as-needed basis. This gives antidiarrheal agents an opportunity to slow peristalsis so food has the most contact with the bowel for absorption.
• Choose medications in either capsule or tablet form. Liquid medications contain sorbitol for palatability, which can cause nausea, vomiting, abdominal cramping, dry mouth, and osmotic diarrhea, and increase fluid and electrolyte losses. Often, liquid medications are prescribed to SBS patients to facilitate absorption, but this isn't always the case as they may contribute to diarrhea.
4. Stool/Enterostomy Output Characteristics
• Dietitians should talk to patients about the consistency, color, and volume of diarrhea or enterostomy output to determine patients' response to medications, assess fluid status, and help guide the nutrition care plan.
5. Oral Supplements and Vitamins
• Encourage patients to add oral nutrition supplements to their diets that are low in carbohydrates/simple sugars. (The "no added sugar" or "diabetes" formulations can benefit patients if sipped slowly.) Oral supplements can benefit SBS patients who can't consume enough calories while they're being weaned from PN to an oral diet.
• Chewable, complete multivitamins are preferred over liquid vitamins that contain sorbitol.
6. Infection Prevention
• Urge patients to practice good hand hygiene before preparing PN solutions to prevent any fecal material from coming into contact with catheters.
• An ethanol lock may help prevent catheter-associated blood stream infections, but it doesn't take the place of good catheter care and hand hygiene practices.1
— MLC
Reference
1. John BK, Khan MA, Speerhas R, et al. Ethanol lock therapy in reducing catheter-related bloodstream infection in adult home parenteral nutrition patients: results of a retrospective study. JPEN J Parenter Enteral Nutr. 2012;36(5):603-610.