Case study
JF, a 28-year-old female, was admitted to the medical-surgical unit. She had a history of Crohn disease that was diagnosed in her teens. Following several exacerbations early in the disease, she underwent a successful resection and anastomosis of the damaged small intestine. Since then, she has required supplemental parenteral nutrition (PN) administered three to four times a week via a central venous port. Her quality of life has been severely disrupted as she is often hospitalized for severe nutritional imbalances. She also appeared emaciated and often complained of a low energy level. She was on various medications to promote intestinal absorption and reduce the need for PN.
After carefully screening her health history, she qualified for treatment with.1 She responded favorably to this medication with a significant increase in her short bowel wall thickness over 6 months, corresponding to a weight gain and an increase in her energy levels. In addition, she reported being able to engage more with her family and friends.
She is currently employed part-time and living independently. She receives financial and residential support and psychosocial therapy arranged by her case manager and social worker. She undergoes regular monitoring for potential complications such as acceleration of neoplastic growth and intestinal obstruction, cholecystitis, and pancreatitis, all related to teduglutide.2 She reports being happy with her life at this time.
Introduction
Short bowel syndrome (SBS) is most often associated with major surgical resection of the small intestine resulting in malabsorption of essential macronutrients and micronutrients. The clinical disease is correlated with the length of the small intestine removed due to its ability to compensate for the loss of reduced absorptive surface area.
Intestinal failure (IF) results when the individual's gastrointestinal function is inadequate and unable to support optimal nutrition and hydration in its present state. The classification of IF is based on the disease severity, which is related to the length and location of the small intestine that has been resected. Because the jejunum is responsible for nutrient absorption, the length and location of small intestine removed significantly impacts the extent of IF. Resections that include portions of the ileum also require fluids in addition to the nutrient supports.3
SBS with IF (SBSIF) is a rare, debilitating malabsorptive disorder resulting in micronutrient and macronutrient malabsorption that decreases the patient's quality of life. IF is an umbrella term that includes surgical SBS (intestinal resection for acquired or congenital gastrointestinal diseases, leading to clinically significant malabsorption and requiring specialized nutritional therapy), as well as disorders of gastrointestinal motility, such as intestinal pseudo-obstruction and congenital enterocyte disorders like microvillus inclusion disease and tufting enteropathy.3
SBSIF is an "orphan" condition: one that occurs in less than 200,000 people.4 Amassing data on the incidence of SBSIF has been difficult because of the condition's rarity and the varied case definitions.
Attempts to effectively manage SBSIF resulted in poor patient outcomes and increased morbidity and mortality as treatment options were expensive because most health insurance plans did not cover them.5 This led to research to improve treatment modalities, including surgery, medical equipment, nutritional products, and nursing care. As a result, in the last 10 years, options for care have advanced significantly to improve patients' quality of life and survival rates.3
This article provides an overview of SBSIF in adults for nurses who encounter patients with this disorder in inpatient and outpatient settings.
Pathophysiology
SBS occurs in neonates and adults.5,6 It is a complicated disease caused by the anatomic loss from a large surgical resection of the small intestine or a functional loss due to a chronic or congenital disease process of the small intestine.7 This results in the inability to maintain optimal levels of protein, macronutrients, micronutrients, and fluids and electrolytes due to a reduced surface area for absorption.7 While the causes for SBS may differ in both populations, its effect on the body is the same. Patients with SBS cannot meet nutritional requirements because they have a reduced ability to absorb nutrients, such as fats, carbohydrates, vitamins, minerals, trace elements, and fluids.8
Malabsorption of macronutrients and micronutrients can result in inadequate growth and development, fluid and electrolyte imbalances, and increased susceptibility to infections. The malabsorption of vital nutrients is proportionately related to the amount of bowel that has been removed or is nonfunctional, as well as whether there is a preservation of the ileocecal valve (ICV) and the large intestine. The ICV acts as a barrier preventing the reflux of contents from the large intestine back to the small intestine. The ICV also regulates the flow of fluids and nutrients from the small intestine toward the large intestine.9
Without supplemental PN or enteral nutrition, SBS can lead to IF with fatal consequences. There is no cure for SBS, but it can be treated effectively. The presentation and severity of signs and symptoms can vary among patients depending on the portion of the affected intestines. Therefore, nurses must understand the anatomy and function of the intestines (see Anatomy and function of the small and large intestines and The digestive system).
In adults, SBSIF may be caused by functional loss or loss of absorptive surface area. Any disease, traumatic injury, vascular disorder, or other pathology that leaves less than 200 cm of viable small intestine or results in a loss of 50% or more of the small intestine places the patient at risk for developing SBS.2
Functional loss is caused by the inability of the small intestine to absorb nutrients despite a normal length. Causes include Crohn disease, mesenteric ischemia, radiation enteritis, intestinal obstruction, dysmotility, and congenital defects.10,11
Loss of absorptive surface area can result from a small bowel resection. A bowel resection may be required because of trauma, bleeding, malignancy, intestinal obstruction, infection, or ischemic necrosis.12 Patients who have undergone massive intestinal resection need nutritional support through various therapeutic measures, including PN.11 It is critical to begin nutritional supplementation to achieve the best possible patient outcomes.
Signs and symptoms
SBSIF is primarily characterized by diarrhea, steatorrhea, sodium depletion, dehydration, and malnutrition. The signs and symptoms vary according to the extent of bowel integrity, length of healthy bowel, and patient age.12 Diarrhea is the most debilitating, common, and life-altering symptom of SBSIF. It can be severe, leading to unintended weight loss, malaise, skin infection, and dehydration.13
The malnutrition associated with SBSIF leads to other associated risks, such as muscle wasting, peripheral edema, and vitamin deficiency.14 Deficiencies of fat-soluble vitamins (A, D, E, and K) and vitamin B12 can cause complications, including night blindness, excessive bleeding, peripheral neuropathy, bone loss, and anemia.15 Loss of small intestine segments results in a change in the levels of the hormones cholecystokinin, secretin, and gastrin, all involved with digestion. This results in increased acid secretion, which causes complications including esophagitis and peptic ulcer disease.16 The malabsorptive challenges associated with SBSIF lead to reduced quality of life and high healthcare costs.
Diagnosis
SBSIF is diagnosed based on the patient's history of gastrointestinal disorders as well as a history of surgical resection of any portion of the small or large intestine. A comprehensive clinical evaluation including lab tests and imaging studies can confirm the diagnosis. The lab tests include serum albumin levels, which may indicate malnutrition when below range or dehydration when elevated; a complete blood cell count for anemia; and a metabolic profile for electrolyte imbalances as well as liver enzymes and creatinine levels to identify liver function and renal clearance, respectively.
Abdominal X-rays, computerized tomography scan of the abdomen, MRI of the abdomen, and abdominal ultrasound can help identify SBSIF by detecting changes in the intestinal wall thickness and possible intestinal obstructions.4
Treatment options
The care of patients with SBSIF has often required prolonged hospital stays to provide frequent supplementation with PN. With the advancement in methods of administration of I.V. supplementation, such as central venous access devices (CVADs) and peripherally-inserted central catheters, it is possible to provide PN in the home setting, thus improving patient quality of life.3,4,17 It has also been beneficial in reducing healthcare costs.
Parenteral nutrition
Patients with SBS initially require PN, which is administered via a CVAD. Many patients will gradually reduce PN as their small intestine recovers and compensates for the functions of the lost portion. This process is called intestinal adaptation. Patients who are unable to absorb sufficient amounts of vital nutrients, fluids, electrolytes, and trace elements, despite receiving other I.V. and oral nutritional supplements, will likely need PN for their lifetime.18
Patients receiving long-term PN support for SBSIF often develop liver dysfunction. Studies have shown that the amount and content of the I.V. lipid emulsion used is closely related to the development of IF-associated liver disease. This is reflected in abnormal liver function tests of patients who receive PN. Including I.V. fish oil lipid emulsions in PN minimizes disturbances in the liver function tests, especially bilirubin levels in hospitalized adult patients.19
Catheter-related bloodstream infection (CRBSI) is a serious complication that can frequently occur with up to 18 catheter infectious events in 1,000 catheter days.20 It is most often caused by poor management of the catheter insertion site. Prolonged use of PN and a lack of enteral feeding may result in small intestine bacterial overgrowth within the gut lining, leading to an increased risk for sepsis. Other complications include the potential for a Clostridioides difficile infection, hyperglycemia, acute kidney injury related to dehydration, and potentially fatal PN-associated cholestatic liver disease defined as conjugated (direct) bilirubin greater than 2 mg/dL.21
Pharmacotherapy
There are various medications with which to treat patients with SBS. An important consideration is the absorption of medications. Increased doses of medications may be required to balance the decreased absorption that is related to SBS. Extended-release medications are not recommended. Alternate routes of administration, such as transdermal, nasal, inhaled, or subcutaneous should be considered.
Teduglutide is a glucagon-like peptide-2 (GLP-2) analogue indicated for the treatment of adults and pediatric patients 1 year of age and older with SBS who are dependent on parenteral support. It is given once daily by subcutaneous injection.22 GLP-2 is a peptide secreted in the distal ileum and the colon. It was found to improve intestinal mucosal growth and its absorptive surface area, which then allows for improved absorption of fluids and nutrients. This has resulted in an improvement in bone mineral density and lean body mass in adults with SBS.3
Teduglutide can cause any abnormal cells in the body to grow faster. Some abnormal cells could become cancerous, increasing the risk of cancer of the liver, gallbladder, pancreas, or intestines and may also increase the risk of colon polyps.6 Patients will need to undergo clinical examinations and repeated colonoscopies (or alternate imaging/diagnostics, such as fecal occult blood testing) during treatment with teduglutide to monitor for the development of polyps and neoplasia of the GI tract.
Antidiarrheal medications include diphenoxylate, loperamide, codeine, and opium tincture. These medications assist with digestion by slowing peristalsis, which in turn prolongs the movement of food through the intestines allowing for increased absorption and decreasing diarrhea.
Patients who have lost all of their colon and ileum and some of the jejunum or patients who do not respond to the treatments mentioned, may be candidates for octreotide which can significantly decrease diarrhea. The use of octreotide has been questioned as it is thought to affect intestinal adaptation by inhibiting hormones released by the intestines that are responsible for intestinal mucosal growth.
Histamine-2 receptor blockers and proton pump inhibitors like famotidine, ranitidine, omeprazole, and lansoprazole have been used to reduce gastric acids.23
The human growth hormone, somatropin has been approved by the FDA for the treatment of SBS. This medication is like the growth hormone that is produced in the pituitary gland. This medication can improve absorption of nutrients in the small intestine and therefore decrease the use of PN.17
Pancreatic enzymes such as pancrelipase and bile-acid resins like cholestyramine may be used. Since food does not stay in the stomach for a prolonged period, it does not have sufficient time to mix with normal pancreatic and biliary secretions that contribute to digestion of fats, fatty acids, and carbohydrates.
Antibiotics may be used in patients who develop small intestinal bacterial overgrowth and probiotics are sometimes used to introduce beneficial bacteria into the gut.23
Intestinal lengthening procedures
Following surgical resection, intestinal adaptation is needed to achieve healthy enteral autonomy defined as being independent of PN support.24 However, this is often impaired by the long-term complications of PN that have been discussed earlier. Autologous intestinal reconstruction surgery is an option to attain enteral autonomy by increasing the absorptive surface area of the intestine wall.
Various surgical reconstruction options are available, ranging from simple procedures like tapering, reversed segments, and colon interposition, to more complex lengthening procedures, such as longitudinal intestinal lengthening and tailoring.14 Longitudinal intestinal lengthening and tailoring (also known as the Bianchi procedure) and serial transverse enteroplasty procedure (STEP) are performed to increase the bowel length with decreasing bowel diameter to increase the absorptive surface area of the intestine, allowing for the patient to be weaned off PN.25 These procedures are performed at any age. The STEP procedure appears to decrease postoperative morbidity and mortality.6
Small bowel transplantation has become the standard of care in some patients with IF. Positive outcomes have been noted for patients with SBSIF who undergo this procedure owing to advances in surgical techniques, immunosuppressive therapy, and postoperative care.26
Nursing considerations
SBSIF is a complex, multifaceted condition requiring diligent assessment to identify and prevent potential, life-threatening complications such as sepsis, fluid and electrolyte imbalance, and loss of central venous access for PN.
Careful analysis of vital signs, lab data, and subjective information should be routinely obtained during a thorough patient assessment. Additionally, a patient who is well educated by the RN about their condition and potential complications will be able to contribute data that may be pertinent in preventing complications and in enhancing a patient's quality of life (see Nursing considerations for patients with SBSIF).
Conclusion
With ongoing clinical research and trials, there has been progress in the treatment and outcomes for patients with SBSIF. However, awareness of SBSIF and ongoing professional education at every level of care is necessary for improving patient outcomes and quality of life.
Anatomy and function of the small and large intestines25
The small intestine is divided into three main portions:
* Duodenum: The first portion, about 30 cm or 12 inches long, is connected to the stomach. Once food is ingested via the mouth, it continues to be broken down in this segment so that the intestinal lining can absorb it along with iron, calcium, and magnesium.
* Jejunum: About 200 cm or 80 inches long, this is the midportion where most nutrient absorption from carbohydrates, fats, proteins, and vitamins occurs.
* Ileum: The last portion of the small intestine is connected to the large intestine. The ileum can adapt to compensate for the loss of jejunum functions. Some end products of digestion not fully absorbed by the jejunum can be absorbed here. Additionally, the final portion of the ileum (terminal ileum) has binding sites for absorbing bile acids and vitamin B12. The ICV is located in the terminal ileum. The ICV's function is to prevent the backward movement of digested material and to slow the transit of intestinal contents to the large intestine to allow for better digestion and absorption of nutrients. Preservation of the ICV with resection is advantageous for individuals with SBS.
Lastly, the large intestine, about 5 feet long in an adult, primarily functions to absorb water and electrolytes and produce vitamin K.8
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