Chapter 70 Short Bowel Syndrome
PATHOPHYSIOLOGY
Short bowel syndrome (SBS) is the syndrome of malabsorption and malnutrition that occurs because of a congenitally malfunctioning bowel or after resection of small bowel necessitated by congenital or acquired conditions (Box 70-1). Symptoms of SBS include chronic diarrhea, impaired nutrient absorption, malnutrition, and poor growth and development. In addition, many affected children are chronically dependent on parenteral nutrition (PN), which can lead to liver dysfunction and disease.
Box 70-1 Etiology of Short Bowel Syndrome
SBS has three characteristic stages. Stage I begins in the immediate postoperative period and usually lasts for 7 to 10 days after the enterostomy is created. Characteristics of this stage include intractable diarrhea with massive water, fluid and electrolyte losses, dependence on parenteral nutrition and, possibly, bowel mucosa atrophy. Stage II begins 2 weeks later and can last up to 1 year after surgery. During stage II, gastric acid hypersecretion can lead to quick intestinal transit time and diarrhea, impaired pancreatic enzyme function, and gastric ulcers. At the end of stage II, stabilization of diarrhea and progression of enteral feedings occur. These changes signal an adaptive hyperplasia of the intestinal mucosa including elongation of both intestinal villi and crypts. Stage III is seen up to 2 years after the surgery. This stage represents control of diarrhea and increased tolerance of enteral nutrition (EN). Oftentimes stomas are reanastomosed at this time. Reaching this stage is dependent upon bowel adaptation, which is critical to the patient with SBS. Bowel adaptation is, in turn, dependent upon many factors, the first of which is intestinal length. Most surgeons agree the 25 cm of small bowel without an intact ileocecal valve (ICV), or 15 cm of small bowel with an intact ICV, is necessary for tolerance of enteral feedings. The second significant factor is the presence of the ICV. The ICV slows intestinal transit time, allowing increased nutrient and fluid absorption, and prevents contamination of the small bowel with colonic flora. Although important, the presence of the ICV is not absolutely necessary, depending on bowel length. The third factor important to bowel adaptation is the location of resection. The adaptive response is greater in the ileum than in the jejunum. Changes in the crypts and the villi allow the ileum to take over some of the functions of the jejunum, whereas the reverse is not true.
The fourth factor in bowel adaptation is the reintroduction of EN. Early and aggressive initiation and advancement of EN, especially human breast milk, protein hydrolysate formulas, or amino acid–containing formulas, appears to promote intestinal adaptation. The fifth factor is the age of the infant at resection. Because intestinal length doubles between the second trimester and full term, a preterm infant has a great capacity for adaptation. The final factor is individual response. Liver tolerance of chronic PN, the number and virulence of infections, and the development of bowel obstructions from strictures or adhesions all seem to play an important role in the overall outcome of patients with SBS.
COMPLICATIONS
1. Gastrointestinal: fluid and electrolyte imbalance, especially in the early postoperative period, diarrhea, gastric acid hypersecretion, gallbladder disease
2. Hematologic: sepsis, hepatomegaly indicative of PN-induced liver disease
3. Nutrition: difficulty advancing enteral feedings, poor growth, vitamin and mineral deficiency, osteopenia, poor healing
4. Integumentary: skin breakdown, especially in the buttocks and the perineum, and at the enterostomy site
5. Developmental: failure to meet developmental milestones; oral aversion
6. Other: need for multiple surgeries, particularly for bowel obstructions
LABORATORY AND DIAGNOSTIC TESTS
Refer to Appendix D for normal values and ranges of laboratory and diagnostic tests.
1. Complete blood count (CBC) with differential and platelet count—may see increased or decreased white blood cell count with sepsis, decreased platelets, and anemia secondary to liver dysfunction
2. Serum electrolytes, glucose, blood urea nitrogen, creatinine—to assess fluid and electrolyte imbalances, tolerance of PN
3. Liver function test—to assess liver tolerance of PN
4. Alkaline phosphatase levels—to assess liver function and monitor course of cholestasis
5. Dipstick or urinalysis for protein, glucose, blood, and ketones—to assess tolerance of PN
6. Gastric pH—to assess the presence of gastric acid hypersecretion
7. Stool hematest, reducing substances, stool ictotest—to assess tolerance of EN and check for the presence of bile in stool
8. Abdominal x-ray study—to check for dilated or obstructed loops of bowel
9. Ultrasound of liver and gallbladder—to check for cholestasis and gallstones
10. Liver scan—uses a radioactive isotope to help determine liver function
MEDICAL MANAGEMENT
The medical management of SBS focuses on the minimization of symptoms through medication and diet therapy. EN is initiated as soon as the postoperative ileus has resolved. Early initiation and aggressive advancement of EN will help promote intestinal adaptation and decrease complications of prolonged PN. Surgical interventions are offered as needed. A number of medications may be used for the complications, as shown in Box 70-2.
Box 70-2 Medications Used to Treat Complications
A Diarrhea
1. Loperamide (Imodium)—an antidiarrheal opioid agent that slows transit time, thereby increasing absorption of water and nutrients
2. Cholestyramine—bile-salt binder to decrease secretory diarrhea
3. Octreotide acetate (Sandostatin)—decreases secretory diarrhea by inhibiting exocrine and endocrine, gastrointestinal, and pancreatic secretions (little is known about effects in infants; decreases insulin and growth hormone levels)
4. Fiber source (Benefiber or pectin)—decreases water content in stool
D Intestinal bacterial overgrowth
1. Trimethoprim (Bactrim)—use a half dose for antibiotic prophylaxis to “sterilize” the intestine and to prevent bacterial overgrowth, translocation, and sepsis.
2. Metronidazole (Flagyl)—same action as trimethoprim
3. Probiotics (CULTURELLE, Lactobacillus GG)—live, human-derived microorganisms that improve intestinal microbial balance
Nutritional interventions for patients in stage I SBS focus on postoperative fluid management and beginning the healing process. Initially, nutrition is provided entirely parenterally through a central venous catheter. PN must be monitored to assure sufficient calories, proteins, and amino acids for healing and sustained growth. In the immediate postoperative period, fluid and electrolyte losses are large, especially sodium. Sodium replacement must occur with a fluid other than PN. Once the postoperative gastrointestinal (GI) motility has returned, trophic low-volume feedings of human breast milk or dilute formula may be initiated. These feedings are advanced aggressively in both strength and volume, as tolerated, based on stool output. Rates as low as 1 ml/hr may prevent mucosal atrophy and decrease intestinal adaptation time.
Nutritional interventions in stages II and III SBS focus on intestinal adaptation and sustaining growth. Enteral feedings of human breast milk or an elemental formula such as Alimentum (Ross Laboratories) or Pregestimal (Mead Johnson) are continued. If the infant is premature, the enteral feedings should be changed gradually to premature formula once feedings are tolerated. Enteral feedings should be given through continuous infusion into the stomach through an orogastric or gastrostomy tube. Increased transit time will maximize absorption. Enteral feeding volumes are advanced based on stool volume output. Feedings are advanced until stool volume output increases by 50% or is greater than 40 to 50 ml/kg/day and/or significant malabsorption occurs. During this time, it is essential to provide an oral motor stimulation program to prevent oral aversion.
Parenteral nutrition should be customized to meet the patient’s changing mineral needs. Supplements of zinc and selenium are often needed, and copper and manganese should be deleted if liver dysfunction develops. Later in stage II, cycling of parenteral nutrition may be attempted. Although this technique remains highly debated, it appears to decrease the incidence of cholestasis and allows for some time with greater freedom of movement for the patient.
Surgical interventions are designed to slow transit time, increase mucosal surface area, or increase intestinal length. Indications for surgical intervention include poor tolerance of EN; numerous complications of PN such as multiple catheter-related infections, which limit venous access; and liver dysfunction and disease. In order to improve nutrient absorption, some surgical interventions focus on slowing intestinal transit time. There are four possible procedures currently being used. The first procedure is the placement of an intestinal valve. Clinical experience is limited, but the intervention is designed to slow transit time in a process similar to the way the ileocecal valve functions. The second procedure is the placement of areversed intestinal segment. A 3- to 6-cm segment of the child’s own bowel is inserted in a position such that retrograde peristalsis occurs, thus increasing absorption time. It is most effective when placed in the distal bowel and is limited to patients who have longer small bowel length. In the third procedure, a colon interposition, a piece of the colon is placed between two segments of small bowel; this may slow transit time by virtue of the colon’s inherently slow peristalsis. The fourth procedure is reversed electrical pacing; electrical signals are applied to the distal region of the small bowel to initiate retrograde peristalsis. This procedure is experimental with no successful clinical reports as yet, but further study is needed.
Surgical interventions that focus on increasing mucosal surface area are the tapering enteroplasty and the neomucosa. In the tapering enteroplasty, the caliber of the dilated small bowel is reduced to a more normal size. In theory, this should increase peristalsis within this segment and decrease bacterial overgrowth. Clinical experience with this procedure is limited. The neomucosa is the transplantation of a patch of intestine with new mucosa. This mucosa has been grown in the laboratory from a cut edge of the normal bowel. To date, this procedure has only been done in animal trials.
The final group of surgical interventions focuses on increasing intestinal length. This procedure includes the Bianchi and Iowa procedures. In the Bianchi procedure the dilated short bowel is divided lengthwise into two separate segments, which are joined together by creating an end-to-end anastomosis; the result is a doubling of length. This procedure has been performed many times with varying clinical results. The Iowa procedure is a two-step surgery. The first step involves securing a segment of bowel under the surface of the liver or the posterior abdominal wall musculature to help the bowel develop neovascularization. The second step of surgery involves longitudinal division of the newly vascularized bowel to increase the length. There is limited clinical experience with this procedure; however, early results are promising.
Bowel and multiple organ transplantation remain as a last option for those patients in end-stage liver disease or with complete intestinal failure. Success has been limited; however, survival rates have improved with more effective immunosuppressive therapy.
NURSING ASSESSMENT
1. See the section on Gastrointestinal Assessment in Appendix A.
2. Assess for fluid and electrolyte imbalances.
4. Assess child’s tolerance of PN.
5. Assess child’s readiness for and tolerance of EN.
6. Assess child for presence of pain (see Appendix I).
7. Assess for signs and symptoms of infection.
8. Assess for signs of skin breakdown.
9. Assess child’s height and weight, head circumference, and pattern of growth (see Appendix E).
10. Assess child’s response to medications.
11. Assess family’s response to hospitalization and child’s condition (refer to Appendix F).
12. Assess family’s readiness for discharge and ability to manage home treatment regimen.
NURSING INTERVENTIONS
1. Assess for fluid and electrolyte imbalances, hydration status, and tolerance of PN.
2. Monitor readiness for and tolerance of enteral nutrition.
3. Monitor for verbal and nonverbal pain behaviors; administer nonpharmacologic and pharmacologic pain measures (see Appendix I).
4. Assess for any signs or symptoms of infection.
5. Monitor for growth deficiencies.
6. Monitor for appropriate growth and development (see Appendix B).
Discharge Planning and Home Care
1. Instruct family about home administration of nutrition.
2. Instruct family about medications—administration and monitoring for desired and undesired effects.
3. Instruct family about care of the central venous catheter and other catheter care.
4. Instruct family about enterostomy care (if applicable).
5. Arrange for and instruct family about follow-up appointments with specialists and primary care physician.
6. Arrange any developmental and/or oral stimulation program follow-up (see Appendix G).
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Kim HB, et al. Serial transverse enteroplasty for short bowel syndrome: A case report. J Pediatr Surg. 2003;38(6):881.
Wales PW, et al. Neonatal short bowel syndrome: Population-based estimates of incidence and mortality rates. J Pediatr Surg. 2004;39(5):690.
Warner BW, et al. What’s new in the management of short gut syndrome in children. Am J Coll Surg. 2000;190(6):725.
