Pediatric Short Bowel Syndrome 

Updated: May 23, 2019
Author: Carmen Cuffari, MD; Chief Editor: Jatinder Bhatia, MBBS, FAAP 

Overview

Practice Essentials

A suggested definition for short bowel syndrome (SBS) in pediatric patients is the requirement for intravenous nutrional and fluid supplementation in those with less than 25% of remaining small bowel that is expected for gestational age.[1] This condition results from the alteration of intestinal digestion and absorption that occurs after extensive bowel resection. It is a complex disorder with nutritional, metabolic, and infectious consequences. Bowel obstruction is a potential complication of SBS (see the image below).

Small-bowel obstruction caused by intussusception Small-bowel obstruction caused by intussusception in a 5-month-old patient is visible on plain radiograph.

Signs and symptoms

Although SBS may rarely be a congenital condition, most patients with SBS have undergone bowel resection for one of the following:

  • A congenital anomaly such as an omphalocele, gastroschisis, or intestinal atresia

  • Necrotizing enterocolitis associated with prematurity[2]

  • Intestinal ischemia from malrotation and volvulus

  • Crohn disease (infrequent with current treatment)

Children with cloacal exstrophy do not have SBS in the classical sense but often have all the signs and symptoms associated with functional intestinal failure.

Patients with SBS may present with any of the following:

  • Nutritional deficiencies

  • Malabsorptive diarrhea

  • Dehydration

  • Vomiting

  • Bloating

  • Gastroesophageal reflux

  • Failure to thrive

  • Drug toxicities

  • Sepsis

See Presentation for more detail.

Diagnosis

Children with SBS should undergo standard hematologic and biochemical studies, according to institutional guidelines. Studies may include the following:

  • Electrolytes, BUN, creatinine, calcium, magnesium, phosphorous - Biweekly in both the initial phase and the late period or at the time of presentation for instability

  • Comprehensive metabolic panel, CBC, triglycerides, cholesterol - Weekly in both the initial phase and the late period or at the time of presentation for instability

  • Folate, vitamin B-12, vitamin E, copper, zinc, selenium - Monthly in both the initial phase and the late period or at the time of presentation for instability

  • Carnitine

The workup for suspected sepsis in patients with SBS may include the following:

  • Blood cultures from both the central and peripheral sites

  • Urinalysis and blood culture specifically to search for fungal infection

  • Abdominal ultrasonography to search for fungal balls in the kidney (only in the case of persistent fungal infection)

  • CT scanning of the abdomen to identify persistent sepsis

  • Ultrasonography of Broviac tip

The workup for suspected bowel obstruction in patients with SBS may include the following:

  • Plain radiography of the abdomen

  • Barium imaging of the bowel

Laboratory procedures may include the following:

  • Upper endoscopy to assess for peptic ulcer disease and possible signs of liver disease (eg, esophageal varices, hypertensive gastropathy)

  • Liver biopsy to evaluate for total parenteral nutrition (TPN)-related liver disease (rarely performed unless the presentation is unusual)

See Workup for more detail.

Management

The management of SBS requires an aggressive multidisciplinary approach that is most often tailored to the individual needs of the patient.[3] Features of treatment include the following:

  • The institution of early and aggressive enteral therapy is the most important stimulus for intestinal adaptation and the eventual discontinuation of parenteral therapy.

  • Teduglutide is indicated for children aged 1 year or older with short bowel syndrome who are dependent on parenteral support.

  • Aggressive resuscitation with fluids, parenteral nutrition, or both is often required in the first week after intestinal resection.

  • Serum electrolytes and a comprehensive biochemical panel should be monitored daily in the early postoperative period and on a biweekly or triweekly basis once the values have stabilized.

  • The hypersecretion noted within the first 12 months postresection is usually treated with H2 blockers or proton pump inhibitors.

  • Parenteral fluid replacement needs may be ongoing, depending on the amount of stool or ostomy output.

  • Bacterial overgrowth in the proximal small bowel may require antibiotic therapy, including metronidazole alternating with either kanamycin or oral gentamicin.

  • Cholestyramine has been used to bind bile salts in patients with choleretic diarrhea.

  • A diverting ileostomy can be used to prevent the stagnation of stool in patients with significant dysmotility.

  • Small-bowel transplantation is used only if absolutely necessary in patients with associated severe advanced liver disease and those with major vascular access problems.

  • Isolated orthotopic liver transplantation without small-bowel transplantation has been demonstrated to be effective.

See Treatment and Medication for more detail.

Background

Short bowel syndrome (SBS) is the result of the alteration of intestinal digestion and absorption that occurs following extensive bowel resection. A suggested definition for pediatric patients is the requirement for intravenous nutrional and fluid supplementation in those with less than 25% of remaining small bowel that is expected for gestational age.[1] Short bowel syndrome represents a complex disorder that affects normal intestinal physiology with nutritional, metabolic, and infectious consequences. Few conditions in pediatric gastroenterology pose as great a challenge as short bowel syndrome.[4]

In general, the leading causes of death in affected infants who are being treated with parenteral nutrition are central line sepsis and liver failure with the prolonged use of parenteral nutrition. 

Pathophysiology

The small intestine of the neonate is approximately 250 cm in length. By adulthood, the small intestine grows to approximately 750 cm. As a consequence, the infant and the young child have a favorable long-term prognosis compared to an adult in regards to potential intestinal growth after intestinal resection. Intestinal adaptation may take weeks to months to be achieved; in the interim, children who have had intestinal resection need nutritional support through various therapeutic measures, including parenteral nutrition. The duodenum and jejunum are responsible for the absorption of most dietary constituents except vitamin B-12 and bile acids.

The jejunum is characterized by long villi and a large absorptive area. The tight junctions are relatively large, rendering the epithelium more porous to larger molecules and the free and rapid flux of water and electrolytes. In comparison, the ileum has shorter villi and a less absorptive surface area than the jejunum. Furthermore, the tight junctions are tighter, permitting less flux of water and electrolytes from the vascular space into the intestinal lumen and, consequently, the ileum is more efficient in the absorption of water. Although nutrients are less well absorbed in the ileum, it has site-specific receptors for the absorption of bile acids and vitamin B12. Moreover, many GI hormones that affect intestinal motility, including enteroglucagon and peptide YY, are produced in the ileum. The small intestinal sites of nutrient absorption are as follows:

  • Duodenum - Iron

  • Jejunum - Carbohydrates, proteins, fat, vitamins

  • Ileum - Bile acids, vitamin B-12

In general, virtually all digestion and absorption is completed within the first 100-150 cm of jejunum in a healthy individual. In the absence of an intact colon, the minimum length of healthy bowel necessary to avoid parenteral nutrition is approximately 100 cm. Patients who have less than 100 cm of jejunum exhibit significant malabsorption. Although the ileum is limited in its capacity to form chylomicrons compared to the jejunum, studies have shown that the ileum has greater adaptive function as far as improving its absorptive function in the presence of short bowel syndrome. Similarly, studies in animals have shown that intestinal transit time is more likely to improve (ie, increase) in patients with proximal small-bowel resection as opposed to patients with distal small-bowel resection.

The jejunum cannot develop site-specific carriers for the transportation of vitamin B12 and bile salts, and, consequently, these are malabsorbed permanently in patients, following ileal resection. Furthermore, the loss of enteroglucagon and peptide YY cannot be underscored in the regulation of small-bowel motility.

In addition to the effects of long-term parenteral nutrition on the liver, small bowel dilation in children with short bowel syndrome is associated with mucosal damage, bowel-derived bloodstream infections, and cholestatic hepatic injury.[5] The presence of a pathologic small bowel diameter ratio exceeding 2.17 was associated with increased fecal calprotectin and decreased citrulline, and small bowel diameter ratio was greater in the presence of intestinal bloodstream infections.[5]

Etiology

Necrotizing enterocolitis, intestinal atresias, and midgut volvulus are the most common causes of short bowel syndrome in the neonatal period.

Intussusception with ischemic small-intestinal injury is a common cause of short bowel syndrome in older infants and children.

Through innovations in the surgical management of patients with chronic inflammatory bowel disease, Crohn disease is a less frequently associated cause of short bowel syndrome.

Prognosis

The long-term survival of children with very short bowel syndrome appears to be excellent—providing no life-threatening complications requiring transplantation develop.[6, 7]  Risk factors for nutritional failure include gastroschisis and delayed ostomy closure. Intestinal rehabilitation may potentially lead to complete weaning of parenteral nutrition before these children reach adulthood.[6]  In general, weaning off parenteral nutrition is strongly dependent on the anatomic profile and length of the residual bowel.[8] Nonetheless, for those who survive as well as their family/caretakers, short bowel syndrome has a significant impact on quality of life, including psychosocial and emotional functioning.[9, 10]

Complications

The leading cause of death in infants with short bowel syndrome who are treated with parenteral nutrition is central line sepsis and complications of the liver and biliary tract associated with the prolonged use of parenteral nutrition.

Cholestasis is also a frequent complication of patients on long-term parenteral nutrition. To some extent, bacterial overgrowth and specific nutrition deficiency can lead to worsening cholestasis in patients with short bowel syndrome. The use of a fish-oil based fatty acid emulsion has been shown to decrease cholestasis once established compared with historic controls.[11]

 

Presentation

History

The history of a patient with short bowel syndrome (SBS) is typically of a child who was born with a congenital anomaly, such as an omphalocele, gastroschisis, or intestinal atresia, and who required a small-bowel resection. In addition, premature infants with necrotizing enterocolitis and require extensive bowel resection with or without the loss of the ileocecal junction also contribute to this patient population.[2]

Other patients present with a past medical history of intestinal ischemia from malrotation and volvulus that required intestinal resection. Congenital short bowel syndrome is a rare cause of short bowel syndrome. Over the last several years, the authors have noted numerous patients with short bowel syndrome associated with cloacal exstrophy. Although these children do not have short bowel syndrome in the classical sense, they behave clinically with all signs and symptoms associated with functional intestinal failure.

Children with short bowel syndrome may present with various medical issues, depending on the extent of their bowel resection and the level of medical complexity. The history should consider all the potential clinical ramifications of managing cases of short bowel syndrome, including those outlined below.

Parenteral nutrition

  • The degree of home nutrition support necessary in the management of a child on total parenteral nutrition (TPN) is noteworthy.

  • Guidelines for the safe use of parenteral nutrition have been established by the American Society for Parenteral and Enteral Nutrition.[12]

  • Patients may present with issues entirely separate from the medical problems related to short bowel syndrome, including problems associated with intravenous access, infection, and signs and clinical symptoms associated with TPN-related liver disease.

Enteral nutrition

  • Quickly initiate enteral feeding for all children with short bowel syndrome.

  • Once again, patients may present with a history entirely separate from the medical problems related to short bowel syndrome, including gastrostomy or nasogastric tube issues. For example, gastrostomy tubes may accidentally fall out. In these patients, the immediate replacement of these tubes is important in maintaining the patency of the tube entry site.

  • Although complications are uncommon, be aware of potential gastric ulceration, gastrostomy tube migrations, and intestinal obstruction, which all may be associated with bilious vomiting and the risk for pancreatitis.

Nutrition

  • Closely monitor all children on long-term enteral and parenteral nutrition for specific nutritional issues.

  • Patients may present with various symptoms related to specific nutritional deficiency, including specific vitamin (or mineral) deficiencies and the related signs, symptoms, and electrolyte abnormalities and their potential complications.

Medical and surgical histories

Obtain a detailed account of the patient's past medical and surgical histories, including the following:

  • The pathology leading up to the surgical resection

  • The extent and location of bowel resection, the presence or absence of the ileocecal valve

  • Medical complications

  • TPN dependency

  • Enteral nutrition

  • Enteral access

  • Type of nutritional formula used

  • Nutritional supplements

  • Medications

  • Allergies

History of complications associated with short bowel syndrome

  • Malabsorptive diarrhea

  • Dehydration

  • Vomiting

  • Bloating

  • Gastroesophageal reflux

  • Failure to thrive

  • Drug toxicities

Physical Examination

During the physical examination, pay close attention to the following clinical signs:

  • Vitals

  • State of hydration

  • State of nutrition, as measured by a patient's weight for height and anthropometric measurements

  • Signs of sepsis

  • Form of nutritional therapy used in the patient (eg, central line access or enteral access)

  • Specific clinical signs of nutritional deficiency

  • Signs of liver disease

 

Workup

Laboratory Studies

Perform standard hematologic and biochemical studies in all children with short bowel syndrome (SBS). Each institution follows its own specific guideline. The following list is not intended to represent an exhaustive list of laboratory evaluations:

  • Electrolytes, BUN, creatinine, calcium, magnesium, phosphorous - Biweekly in both the initial phase and the late period or at the time of presentation for instability

  • Comprehensive panel, CBC count, triglycerides, cholesterol - Weekly in both the initial phase and the late period or at the time of presentation for instability

  • Folate, vitamin B-12, vitamin E, copper, zinc, selenium - Monthly in both the initial phase and the late period or at the time of presentation for instability

  • Carnitine

Microbiology

  • Any suspicion of sepsis necessitates blood cultures. Children with short bowel syndrome are susceptible to intestinal bacterial translocation, with the central line as the most likely source of seeding. They are also susceptible to translocation of skin flora such as Staphylococcus species.

  • Obtain blood cultures from both the central and peripheral sites.

  • Consider opportunistic infections, including fungal infections, in the differential diagnosis of a child presenting with sepsis. Obtain a urinalysis and blood culture in these children specifically to search for fungal infection.

Imaging Studies

Imaging studies are needed to assess for potential complications, including those outlined below

Infection

  • Abdominal ultrasonography to search for fungal balls in the kidney

  • Computed tomography (CT) scanning of the abdomen to identify sepsis

  • Ultrasonography of Broviac tip

Bowel obstruction

  • Plain radiography of the abdomen (see image below)

    Small-bowel obstruction caused by intussusception Small-bowel obstruction caused by intussusception in a 5-month-old patient is visible on plain radiograph.
  • Barium imaging of the bowel

Liver disease

  • Abdominal ultrasonography to study the liver, biliary tract, and spleen, as well as assess for the presence of ascites

  • Abdominal ultrasonography with Doppler to assess portal flow

Potential liver or bowel transplant

  • Volumetric CT scanning of the liver

  • Possible angiography

Procedures

Children with short bowel syndrome may require laboratory procedures, including the following:

  • Upper endoscopy to assess for peptic ulcer disease and possible signs of liver disease (eg, esophageal varices, hypertensive gastropathy)

  • Liver biopsy to evaluate the patient for signs of total parenteral nutrition (TPN)-related liver disease (This is rarely performed unless the presentation is unusual.)

 

Treatment

Approach Considerations

A multidisciplinary team should closely monitor patients with short bowel syndrome (SBS).

The gastroenterologist, nutritionist, and pharmacist who manage the patient's total parenteral nutrition (TPN) are integral to the success of outpatient management of the patient with short bowel syndrome. The cooperation between these health care providers and home care nursing services is necessary for the proper surveillance of patients with short bowel syndrome and the execution of investigative testing and treatments.

The frequency of home testing, nurse visitation, outpatient follow-up, and hospitalization often lead to noncompliance, morbidity, and treatment failure.

Medical Care

The management of short bowel syndrome (SBS) requires an aggressive multidisciplinary approach that is most often tailored to the individual needs of the patient.[3] Nutrition plays an important role in the management of short bowel syndrome. The institution of early and aggressive enteral therapy is the most important stimulus for intestinal adaptation and the eventual discontinuation of parenteral therapy.

Medical therapies

Teduglutide is synthetic analog of glucagonlike peptide 2 (GLP-2), a naturally occurring gut peptide with trophic effects on the intestinal villi. The US Food and Drug Administration (FDA) gave approval in 2012 for the use of teduglutide among adult patients with short bowel syndrome; in May 2019, it gained FDA approval for children as young as 1 year.[13, 14] Teduglutide has been shown to increase villous height and crypt depth among patients with short bowel syndrome and to increase both fluid and macronutrient absorption. Most studies showed that the drug was well-tolerated; however, the potential risk for intestinal adenomas demands that all patients undergo a screening colonoscopy prior to its use.[15]   

Approval of teduglutide in children was supported by a study in 69 children with short bowel syndrome who chose to take the drug or receive standard care.[15] Patients who chose to receive teduglutide treatment were subsequently randomly assigned to 0.025 mg/kg/day (n = 24) or 0.05 mg/kg/day (n = 26); nine patients received standard care. At the end of the 24-week study, 69% of patients who took teduglutide 0.05 mg/kg daily reduced their volume of parenteral support by 20% or more. Based on patient-diary data, patients who received this dose of the drug experienced a 42% mean reduction in parenteral support volume (mL/kg/day) from baseline (-23 mL/kg/day from baseline).[15]

Other outcomes at 24 weeks showed 38% of patients in the 0.05 mg/kg dose group were able to reduce parenteral support infusion by at least 1 day per week. There was also a reduction in infusion time by 3 hours per day on average compared to baseline. During the study, three children (12%) were completely weaned off parenteral support.[13, 16]

Codeine and loperamide can be used in pediatric patients to slow intestinal transit time; however, results have been mixed because of concerns for worsening of bacterial overgrowth. Octreotide is rarely used to limit the amount of intestinal losses after bowel resection. Its use in pediatric patients is controversial because of concerns of the effect on growth and worsening cholestatic liver disease. Cholestyramine has been used as a means of binding bile salts in patients with choleretic diarrhea. Antibiotics are sparingly used to prevent small-bowel overgrowth.

Children, especially young infants, also have a greater capacity to adapt than adults in response to massive small bowel resection. Numerous physiological responses to short bowel syndrome are observed. Although the small intestine is unable to extend itself in length, it does have the capacity to hypertrophy by increasing the number and size of intestinal villi, as well as crypt depth. All these adaptive functions are important in increasing intestine’s absorptive surface area by increasing mucosal mass.

Several mechanisms are involved in stimulating mucosal hypertrophy, including hormones secreted by the small bowel on exposure to intraluminal nutrients, as well as intestinal growth factors produced by both the pancreas and biliary system. Intestinal growth factors, including glucagonlike peptide and other proglucagon-derived peptides produced by the epithelium have been shown to stimulate intestinal growth and adaptation. Similarly, non-GI hormones (eg, cortisol, thyroxin) may also be involved. Mucosal hyperplasia also depends on exposure to intraluminal contents. Certain dietary components have a trophic influence on the intestinal mucosa; thus, an aggressive provision of enteral nutrition can be regarded as an important therapeutic tool in allowing for intestinal adaptation.

Glutamine is an important fuel for the intestinal mucosa and has been shown to stimulate mucosal growth. However, most clinical trials have not shown any selective advantage with the supplementation of children with short bowel syndrome with pharmacological doses of glutamine.[17]  The same can also be said with the supplementation of pharmacological doses of cholecystokinin.

An uncontrolled clinical trial using intravenous cholecystokinin in patients with short bowel syndrome and cholestasis did not show any added therapeutic benefit. The authors are also in the process of investigating the usefulness of choline therapy. The authors' experience has shown that the best way of managing cholestasis is usually through aggressive weaning of parenteral nutritional therapy because patients with short bowel syndrome show improved tolerance of enteral feeds. If parenteral nutrition cannot be entirely weaned, the authors tend to selectively eliminate amino acid and fat supplementation, assuming that the patient’s nitrogen balance and caloric needs are being met through enteral nutrition.

Parenteral nutrition

The length and function of the remaining intestine and the presence of normal physiologic mechanisms that regulate intestinal transit time, including the ileocecal valve and colon, determine whether the patient requires a limited course of specialized enteral therapy or prolonged total parenteral nutrition (TPN).

In 1991, Goulet et al studied the relative importance of several clinical factors in predicting the long-term needs for parenteral nutrition.[18] In 54 neonates who underwent extensive small-bowel resection, the presence of less than 40 cm of small intestine in children with either colonic resection or an absent ileocecal valve had a strong association with a prolonged need for parenteral nutrition (>48 mo).

Although this has been the experience at most pediatric tertiary care centers that care for children with short bowel syndrome, the authors' collective experience at The Johns Hopkins Children’s Center suggests that, with aggressive introduction of continuous modular enteral feeds and selective weaning of protein and fats from the parenteral nutrition, children with extensive small bowel resection may be salvaged sooner and weaned off of parenteral nutritional support. The ultimate goal is avoiding the need for either liver or multivisceral transplantation.

Teduglutide has been shown to reduce the need for parenteral support.[19] Studies have found that treatment with teduglutide has resulted in enhancement or restoration of the structural and functional integrity of the remaining intestine and has reduced the need for parenteral nutrition support in patients with short bowel syndrome and intestinal failure.[20]

Excessive fluid losses

Massive fluid and electrolyte losses are usually observed during the first week after excessive intestinal resection. Patients with short bowel syndrome most often require aggressive resuscitation with fluids or parenteral nutrition, or both. Instituting enteral therapy as soon as possible is very important in order to facilitate the adaptive intestinal response.

In the early postoperative period, monitor serum electrolytes and a comprehensive biochemical pattern daily. When these values have stabilized, monitor them on a biweekly or triweekly basis. The hypersecretion noted within the first 12 months postresection is usually treated with histamine 2 (H2)–receptor antagonists or proton pump inhibitors.

The provision of adequate parenteral fluid replacement needs may be ongoing depending on the amount of stool or ostomy output. Indeed, enteral nutrition can cause significant osmotic diarrhea.

Malabsorption

Extensive jejunal resection leads to carbohydrate malabsorption. The undigested foods produce an osmotic diarrhea typical of most patients with short bowel syndrome. The proximal small bowel is also important in the absorption of proteins, fat, and certain micronutrients, including copper.

Extensive resection of the ileum may lead to severe malabsorption of bile salt and vitamin B-12. Bile salt malabsorption produces a choleretic diarrhea. Furthermore, bile salt depletion affects fat absorption, thereby worsening steatorrhea and fat-soluble vitamin malabsorption. Ileal resection leads to the malabsorption of bile salts and an abnormal bile acid pool that leads to the formation of a lithogenic bile and cholelithiasis.

The ileocecal valve is important in preventing bacterial overgrowth. Problems associated with proximal small-bowel overgrowth include deconjugation of bile salts and depletion of bile salt stores. Bacteria often compete for vitamin B-12, which may facilitate a pernicious anemia. Bacteria overgrowth also leads to carbohydrate malabsorption, worsening of osmotic diarrhea, and increased risk of metabolic acidosis and dehydration. Treatment is generally aimed at lessening the degree of bacterial overgrowth with antibiotic therapy, including administration of metronidazole alternating with either kanamycin or oral gentamicin.

Motility disturbances

Patients with short bowel syndrome have a decrease in intestinal transit time. Patients with extensive proximal small-bowel resection have increased gastric emptying, thereby further decreasing intestinal transit time.

The absence of normal physiologic mechanisms that increase intestinal transit, including the ileocecal valve and colon, also shortens intestinal transit time. However, if the existing small bowel or colon shows signs of dysmotility due to fibrosis or surgical narrowing, stagnant bowel contents may aggravate an existing bacterial overgrowth, thereby worsening malabsorption and diarrhea.

Small-bowel overgrowth also leads to d-lactic acidosis and may be associated with CNS disturbances. Antibiotics are used to prevent small bowel overgrowth and should be cycled on a weekly or biweekly basis. Numerous potential antibiotic therapies can be used. At the Johns Hopkins Children’s Center, metronidazole, kanamycin, nitazoxanide and rifaximin are the preferred therapies used in managing patients with small bowel bacterial overgrowth.

Short bowel syndrome associated colitis is not an infrequent complication. Patients often present with hematochezia and have histologic signs of colitis on intestinal biopsies.

In patients where the colon is not removed, histological signs of colonic mucosal hypertrophy that serves to increase colonic fluid and electrolyte absorption are noted. Studies have shown that these adaptive responses may actually be hormonally mediated by various growth factors, including glucagonlike polypeptides. Although a functional colon is always preferred in short bowel syndrome, patients who exhibit colonic dysmotility may generally achieve a more rapid advancement with enteral feeds with a diversion proximal colostomy. The authors' experience at The Johns Hopkins Children’s Center has shown that prokinetic agents such as erythromycin and raglan have limited efficacy in improving residual bowel function, especially in patients with significant small and large bowel dysmotility.

Among patients with significant dysmotility issues, the authors' experience has shown that a diverting ileostomy can be used to prevent the stagnation of stool. By establishing a good flow of stool, enteral feeds are allowed to continue and be maximized. Rectal tubes can also be used to facilitate the flow of stool, albeit somewhat problematic in the older child. Among those children that a rectal tube is only partially effective, a diversion ileostomy can be performed.

Patients with ongoing issues of dysmotility should have a small bowel enema performed to rule-out intestinal strictures. Those lesions should be dealt with by surgery. Furthermore, proximal GI issues, including gastroparesis can be medically treated; however, the authors' experience has shown that among the most refractory cases that postpyloric feeding tubes are required.

Gastric acid hypersecretion

Gastric acid hypersecretion is common in patients with short bowel syndrome. The degree of hypersecretion is proportional to the degree of bowel resected. Hypersecretion may contribute to malabsorption by inactivating pancreatic enzymes and, thus, interfering with fat absorption. The usual treatment is with H2 blockers.[21]

Although the usual treatment is with H2 blockers, the availability of proton pump inhibitors especially in pharmacological forms conducive to the needs of children with enteral feeding tubes has now been the treatment therapy of choice in managing children with short bowel syndrome and gastric acid hypersecretion.

Surgical Care

Surgical care is related to venous access (ie, central line placement to provide TPN). The loss of intravenous access through repeated episodes of sepsis and thrombosis can lead to the early need for intestinal transplantation despite good hepatic function. Surgery may be required for gastrostomy tube placement to provide for enteral access.

Intestinal lengthening procedures and transplantation are always avoided if at all possible. Several attempts at increasing bowel length through surgical means have been made over the last decade. The bowel is transected longitudinally to preserve the blood supply. The largest experience comes from the University of Nebraska. In this experience, surgical intervention improved intestinal adaptability and weaning from parenteral nutrition in a dozen patients. However, with repeated surgical interventions, the risk of intestinal stricture formation increases, as well as the risk of small-bowel obstruction secondary to adhesion formation.

Small-bowel transplantation has shown mixed success. The problems associated with transplantation, including the need for immunosuppression and the risk for intestinal rejection and lymphoproliferative disease, has limited this treatment option for most patients with short bowel syndrome unless absolutely necessary in patients with associated severe advanced liver disease and those with major vascular access problems. Isolated orthotopic liver transplantation without small-bowel transplantation has been demonstrated to be effective.

Consultations

The authors' experience has also shown that most catheter infections can be managed on an out-patient basis.[22] With a robust nursing home support mechanism, most infections, including fungal infections can be managed effectively at home. This clinical approach requires a committed family willing to take on this responsibility in administering intravenous antibiotics and a specialized medical support system that sustains an optimized level of communication with the family, especially during the weekends and evenings. When sepsis is present with no identifiable bacterial source, the aid of an infectious disease specialist may be requested.

In addition to consultation with a gastroenterologist, in the setting of fungemia, consulting an infectious disease specialist to guide antifungal therapy is best and, in the setting of liver or intestinal failure, consult a transplant surgeon.

Diet

Enteral therapy

In infants with massive small-bowel resection, enteral nutrition is initiated very quickly by using elemental formulas. The mixture of monosaccharides and polysaccharides is preferred to disaccharides in order to limit osmotic load, in combination with long-chain triglycerides (LCT) and medium-chain triglycerides (MCT). The authors favor starting with formulas that are either one-fourth or one-half strength, depending on the patient's tolerability, and increasing in volume before increasing energy density. Oligopeptide formulas are better absorbed than elemental amino acid formulas because di-tripeptide absorption exceeds that of amino acids.

MCTs are important in the dietary management of patients with short bowel syndrome because they are readily absorbed in the stomach and proximal small bowel, thereby improving fat and total energy absorption. Current recommendations are to use MCTs as the main source of fat and energy needs. Long-chain fatty acids are required to prevent essential fatty acid deficiency and should make up approximately 10% of the patient's energy needs. Long-chain fatty acids may have a trophic effect on the intestinal mucosa.

The question of fat intolerance has always been a point of contention; however, the use of long-chain fats, which have increased energy density, is usually better tolerated than use of carbohydrates. Testing the tolerability of either fats or carbohydrates and adjusting the modular formula accordingly is advisable. In some cases, providing carbohydrates parenterally and providing fats enterally is preferred in order to improve a patient's tolerance. The use of continuous enteral feeds is better tolerated than bolus feeds in patients with small-bowel resection. An increase in stool output with the appearance of fecal-reducing substances is an indication that the patient may have reached the tolerance limit.

Enteral nutrition remains the lone medical therapy that can facilitate intestinal adaptation. The residual bowel must be constantly exposed to nutrients in order to allow the bowel to adapt. Hence, the physician must be able to allow for substantial stool volume and frequency, as long as it does not compromise the child's hydration, acid base balance, and serum electrolyte levels. A common mistake is the tendency to either stop enteral feeds or substantially lower the volume and frequency of feeds in response to changes in stool volume. Most fluid and electrolyte perturbations that result from short bowel syndrome, or in response to modifications in enteral nutritional therapy, can be easily compensated through an adjustment in the parenteral formula. If possible, the physician should avoid altering the rate or the concentration of the enteral formula too aggressively, in order to allow the adaptive process to proceed.

Many animal models have shown that the bowel is very sensitive to starvation. In the absence of enteral nutrition, the crypt cell population decreases and epithelial cell cycle increases, thereby decreasing the proliferation of the intestinal epithelium. In contrast, in response to a continual and large supply of enteral nutrients, crypt cells proliferate, leading to an increase in crypt depth and lengthening of the intestinal villi. An increase in the absorptive area does not always coincide with functional adaptation.

The production of digestive enzymes and nutrient receptors is in direct response to the quality and quantity of intestinal nutrients. The physician must ensure a constant provision of macronutrients, in order to facilitate this adaptive process. The adaptive process may, in large part, also depend on the production of trophic intestinal hormone and secretions that are produced in response to nutritional therapy.

In a healthy individual, other than fluid and calcium absorption, the colon has a limited absorptive capacity; however, in patients with short bowel syndrome, the colon may assume an increased nutritional role. The colonic flora is capable of metabolizing nonabsorbed starch and fiber into the production of short-chain fatty acids. These short-chain fatty acids are regarded as the preferred fuel for the colon and may actually stimulate water absorption. Therefore, the residual colon may provide an opportunity to improve water absorption in patients with short bowel syndrome.[23]

Decreasing the amount of carbohydrates within the enteral feeds and decreasing the volume and concentration of feeds help manage the problems with excessive stool volume and abdominal distension in the setting of significant malabsorption. The addition of fiber can also increase stool frequency. Decreasing either the volume or rate of feeds may treat patients with gastroesophageal reflux and vomiting. The advancement of enteral feeds is based on the patient's tolerance.

Parenteral therapy

Provide parenteral nutrition to patients with massive intestinal resections as soon as possible. Increase parenteral nutrition accordingly, based on the patient's tolerance level. Before the availability of parenteral nutrition, most patients with short bowel syndrome died. The dramatic improvement in patient survival primarily is because of advances in parenteral nutrition. Today, survival has been shown in patients with as little as 11 cm of proximal small bowel and an ileocecal valve to as little as 25 cm of small bowel without an ileocecal valve. Anecdotal reports of children surviving with as little as 12 cm of bowel without an ileocecal valve are also noted. The clinical factors that are associated with prolonged (>2 y) parenteral nutritional requirements include the following:

  • Residual bowel

  • Limited absorptive function

  • Bowel adaptation (ileum has greater adaptability than jejunum)

  • Dysmotility

  • Bowel length (< 40 cm)

  • Absent ileocecal valve

  • Colon resection

  • Bacterial overgrowth

Several strategies have been proven to improve a patient's tolerance of parenteral nutrition in the setting of short bowel syndrome, including limiting the amount of toxic amino acids administered parenterally and providing protein requirements enterally with specialized infant amino acid formulas. Similarly, because enteral feeds are known to facilitate bile flow, the initiation and progression of enteral feeds may actually prevent cholestasis. Choleretic agents, such as phenobarbital and ursodeoxycholic acid, have also been shown to help treat cholestatic liver disease. Patients on long-term parenteral nutrition are at risk for central intravenous catheter infection and sepsis. Patients require aggressive home care nursing and the outpatient execution of investigations, including hematologic, biochemical, and microbiologic testing.

Moreover, these patients are at risk for intestinal bacterial translocation. Approximately 20% of all central venous catheters are removed secondary to recurrent infection. In the author's experience at the Johns Hopkins Hospital, approximately 90% of central venous catheter infections can be cleared with antibiotics alone. The role of prophylactic antibiotic therapy is controversial.

Specific nutrient requirements

Multivitamins and minerals are preferentially administered parenterally in patients with extensive small-bowel resections. In the presence of significant steatorrhea, water-soluble forms of vitamin A, vitamin E, and vitamin D are available commercially. Because calcium supplementation is important in the setting of vitamin D deficiency and malabsorption, provide supplementation enterally in order to allow for bone mineralization and growth. Regularly monitor serum calcium. Dual energy x-ray absorptiometry (DEXA) scanning may be used to monitor bone density. Because enteric bacteria synthesize vitamin K, supplementation is not necessary but can be monitored with the measurement of prothrombin time. The deficiency of water-soluble vitamins is rare.

Vitamin B-12 can be administered parenterally on a monthly basis as needed in patients with extensive ileal resections. It is also available as a nasal gel. Patients with iron deficiency secondary to either bacterial overgrowth or malabsorption should be monitored carefully and can be supplemented with intravenous iron infusions. Zinc supplements are often needed secondary to increased fecal losses. In individuals who are not on parenteral nutrition, zinc supplements can be provided in tablet form. Other micronutrients, including manganese and selenium, can be provided in pharmacologic doses as required. Although copper deficiency is rare, deficiency has been associated with anemia and cardiomyopathy. Periodic measurements of copper and selenium are merited for individuals on long-term parenteral nutrition.

Outcome

The successful nutritional management of patients with short bowel syndrome has increased long-term survival rates. The complex pathophysiology of short bowel syndrome often requires a multidisciplinary approach to patient management. Additional experience with adjunct medical and surgical therapies will potentially expand existing treatment options, thereby improving patient survival and precluding potential complications associated with long-term parenteral nutrition support.

 

Medication

GLP-2 Analogs

Class Summary

Analogs of a naturally occurring glucagonlike peptide-2 (GLP-2) bind to the GLP-2 receptors located in intestinal subpopulations of enteroendocrine cells, subepithelial myofibroblasts, and enteric neurons of the submucosal and myenteric plexus.

Teduglutide (Gattex)

Binds to GLP-2 receptors and activates local release of intestinal mediators that increase intestinal absorptive capacity, resulting in increased fluid and nutrient absorption. It is indicated for children aged 1 y or older with short bowel syndrome who are dependent on parenteral support.

Antibiotics

Class Summary

These agents are used sparingly to prevent small-bowel bacterial overgrowth. They are used on a biweekly basis to prevent bacterial resistance.

Metronidazole (Flagyl)

Used to prevent intestinal small-bowel bacterial overgrowth.

Gentamicin (Garamycin, Gentacidin)

Aminoglycoside antibiotic for gram-negative coverage. May be used to prevent bacterial overgrowth in children with SBS.

Consider if penicillins or other less toxic drugs are contraindicated.

Gentamicin works well when administered PO to prevent intestinal overgrowth.

Drug interactions and precautions are likely to be clinically insignificant because PO gentamicin has minimal systemic absorption.

H2 blockers

Class Summary

This agent is one of two treatment modalities used for gastric acid hypersecretion.

Ranitidine (Zantac)

Inhibits histamine stimulation of the H2 receptor in gastric parietal cells, which in turn reduces gastric acid secretion, gastric volume, and hydrogen concentrations.

Proton pump inhibitors

Class Summary

This agent is one of two treatment modalities used for gastric acid hypersecretion.

Omeprazole (Prilosec)

Decreases gastric acid secretion by inhibiting parietal cell H+/K+ -ATP pump.

Choleretic agents

Class Summary

These agents improve biliary flow and prevent total parenteral nutrition (TPN)-induced liver disease.

Ursodiol (Actigall, Urso)

Also called ursodeoxycholic acid. Improves bile acid–dependent bile flow.

Phenobarbital (Barbita, Luminal, Solfoton)

Improves bile acid–independent flow.

Bile salt binders

Class Summary

These agents decrease choleretic diarrhea.

Cholestyramine (Prevalite, Questran)

Forms a nonabsorbable complex with bile acids in the intestine, which in turn inhibits enterohepatic reuptake of intestinal bile salts. Effective in reducing the choleretic diarrhea in patients with SBS.

Antisecretin agents

Class Summary

These agents decrease intestinal secretions.

Octreotide (Sandostatin)

Acts primarily on somatostatin receptor subtypes II and V. Inhibits GH secretion and has multitude of other endocrine and nonendocrine effects, including inhibition of glucagon, VIP, and GI peptides.

Hypomotility agents

Class Summary

These agents increase intestinal transit time.

Loperamide (Imodium, Kaopectate)

Acts on intestinal muscles to inhibit peristalsis and slow intestinal motility. Prolongs movement of electrolytes and fluid through bowel and increases viscosity and loss of fluids and electrolytes.