Approach
The main goal of treatment is to ensure hydration, electrolyte balance, and nutrition during the period of intestinal adaptation. The ultimate aim is to return the patient to as normal a lifestyle as possible by reducing and ideally eliminating the need for PN.
Treatment depends upon the extent and anatomy of bowel resection and involves dietary alteration (including the need for increased energy intake), nutrient and fluid supplementation, and medications to minimize fluid losses and to control diarrhea.[4] In patients with irreversible intestinal failure, the absorptive capabilities of the small intestine are never recovered, and these patients require long-term PN.[1] Such patients will have a recurrence of weight loss, volume depletion, electrolyte imbalance, or malnutrition when PN weaning is attempted.
Surgical interventions are used to aid intestinal adaptation. A functioning colonic anastomosis is essential for adaptation, and reanastomosis of the colon is therefore a key surgical intervention.
Patients who are deemed to have PN failure require rescue therapy with intestinal transplantation or combined liver and intestinal transplantation.
Patients with jejunoileocolic anastomosis
Management primarily depends on the length of residual small bowel.
Patients with >100 cm of residual small bowel (or >150 cm if the colon is partially resected) may not require any PN support and can be managed with diet alone. Partial PN support with weaning can be initiated if adequate nutritional status is not achieved.
Patients with ≤100 cm of residual small bowel (or ≤150 cm if the colon is partially resected) usually require partial PN support in combination with oral diet. Patients with a jejunoileocolic anastomosis have the greatest likelihood of weaning from PN.[4]
All patients require electrolyte/micronutrient monitoring and replacement with oral rehydration. Gastric acid hypersecretion and diarrhea must be controlled if present.[4]
Patients should be encouraged to eat a diet rich in complex carbohydrates, starch, and soluble fiber, which can be synthesized in the colon to short-chain fatty acids, providing an extra source of energy.[23] Because the colon is in continuity, these patients are at risk for oxalate kidney stones and should also be instructed on a low oxalate diet.[4] Additional oral calcium supplementation may be beneficial.
Patients with jejunoileal anastomosis and a fully resected colon
The colon has a critical role for water and nutrient absorption, which is lost in this patient group. In addition, synthesis of vitamin K by the colonic intestinal flora (which could partially compensate for the intestinal malabsorption of vitamin K) is also lost, leading to a risk of severe vitamin K deficiency.
Most patients require PN. Those with 100 cm to 200 cm of residual small bowel usually require partial PN support in combination with oral diet. All patients also require electrolyte/micronutrient monitoring and replacement with oral rehydration. Gastric acid hypersecretion and diarrhea must be controlled if present.[2][4]
PN weaning should be attempted but may not be successful. Patients with ≤100 cm of residual small bowel will almost assuredly have dependence on PN.
Patients with end-jejunostomy or duodenostomy
These patients have the highest risk of chronic intestinal failure unless a primary reanastomosis to the colon is performed. In addition, these patients are at risk for water-soluble as well as fat-soluble vitamin deficiencies.
Primary reanastomosis of small bowel with colon must be performed in all patients whenever possible. This enables the intestine to take advantage of the colon's abilities during adaptation and greatly improves the patient's chances of weaning from PN.
Patients require total PN support for the first 7 to 10 days after surgery, after which partial PN support in combination with oral diet should be commenced. Patients with >100 cm residual small bowel (or >150 cm if the colon is partially resected) can be transitioned to oral diet relatively quickly, while those with ≤100 cm residual small bowel (or ≤150 cm if the colon is partially resected) may require PN for longer.
All patients require electrolyte/micronutrient monitoring and replacement with oral rehydration.[2] Gastric acid hypersecretion and diarrhea must be controlled if present.[2][4]
Patients should be encouraged to eat a diet rich in complex carbohydrates, starch, and soluble fiber, which can be synthesized in the colon to short-chain fatty acids providing an extra source of energy.[23] The creation of a colonic anastomosis places patients at risk for oxalate kidney stones and patients should therefore be instructed on a low oxalate diet.[4]
Parenteral nutrition
PN therapy
The decision to start PN is guided initially by the extent and anatomy of bowel resection and reviewed according to the clinical response. Most patients have had extensive rather than limited bowel resections and will require PN initially.
Necessary nutrition is given over a 24-hour period, with efforts made to infuse the daily nutritional requirements over a shorter timeframe so that the patient can remain free of the pump for some of the day (called cycling). The aim is to transition the patient to a 10- to 12-hour night-time feeding schedule so that hypothalamic hunger drive can be preserved during the daytime. At the end of a feeding period, PN should be tapered over 30 to 60 minutes to avoid hypoglycemia.
Catheter safety instructions are critical for the prevention of complications such as catheter sepsis and venous thrombosis.
Weaning from PN
This is determined by the rate of intestinal adaptation and can take up to 2 years, but may be longer in very rare cases. There are little data available to confirm the period of greatest and most complete or maximal adaptation.
Weaning is achieved by gradually increasing oral intake in small, frequent feedings as tolerated. This is accompanied by: a corresponding adjustment to the frequency and content of PN; monitoring of fluid and nutrition status; diarrhea control; and use of oral rehydration solutions. Patients should aim to consume 2 to 3 times their normal caloric intake during weaning. Once successfully weaned, increased caloric intake with oral rehydration and dietary changes should be continued.
PN dependency and PN failure
PN dependency
Patients with true intestinal failure will have a recurrence of weight loss, volume depletion, electrolyte imbalance, or malnutrition every time a reduction in PN is attempted. These patients are PN-dependent and require long-term PN support. Liver function must be monitored to prevent and detect liver failure, a known complication of long-term intestinal failure.[2]
Teduglutide, a human glucagon-like peptide-2 (GLP-2) analog administered subcutaneously, has been shown to improve intestinal absorption and reduce PN requirement in PN-dependent patients with SBS.[24][25] Weaning may be attempted after 4 weeks of treatment with teduglutide, and lifelong continuous treatment is required if weaning is successful. However, there is uncertainty regarding optimal maintenance dosing. There is a risk of acceleration of neoplastic growth with teduglutide. Small bowel neoplasia has been reported in animal studies and there is a theoretical risk of colorectal cancer in humans.[26] Therefore, patients with an intact colon require colonoscopy before starting treatment, and then at regular intervals during treatment (no less frequently than every 5 years). Treatment should be discontinued in patients with gastrointestinal malignancy, and caution should be used in patients with nongastrointestinal malignancy.
PN failure
Patients can be considered to be failing PN therapy if they have one or more of the following:[2][11]
Impending or overt liver failure because of intestinal failure-associated liver disease (IFALD)
At least two thromboses of major central venous vessels
Frequent central line-related sepsis (>2 bacterial infections annually or 1 fungemia ever)
Frequent severe volume depletion.
PN composition should be adjusted in patients developing IFALD. Dextrose overfeeding (>40 kcal/kg/day) should be avoided, and intravenous lipid intake reduced to under 1 g/kg/day if possible.[2] However, the intravenous soybean oil-based lipid emulsion should still supply at least 4% to 8% of total energy in order to avoid essential fatty acid deficiency. This usually requires an overall reduction in caloric intake, as overfeeding needs to be avoided. Alternative lipid emulsions, containing fish oil or a combination of fish and olive oils, may be used as an energy source in patients with IFALD.[27][28]
If there is no clinical improvement after PN adjustment, or PN failure has occurred owing to recurrent thromboses of central venous vessels or frequent severe volume depletion, the patient should be referred to a small bowel transplant center for intestinal transplantation.
Frequent central line-related sepsis is a controversial criteria for PN failure and is not well adopted owing to the high incidence of post-transplant infection.[11] Furthermore, catheter sepsis is commonly related to poor catheter care technique. It is the author’s opinion that frequent catheter infection is a risk factor for post-transplant infection, and that improved instructions for catheter care that includes return demonstration may be a more suitable option for the patient than an intestinal transplant. Intestinal transplantation is reserved as a final option, because of the associated risk of high morbidity and mortality. Patients with end-stage liver disease will require combined liver and intestinal transplantation. Ideally, early isolated small bowel transplantation avoids the need for liver/intestine transplantation. Due to anatomic considerations, multivisceral transplantation is rarely required.
Bowel lengthening/tapering surgery for PN-dependency
PN-dependent patients with dilated bowel segments can undergo a bowel lengthening/tapering surgical procedure, such as the Bianchi procedure or the serial transverse enteroplasty (STEP) procedure, which can aid intestinal adaptation and weaning from PN.
The Bianchi procedure takes an immotile segment of small bowel, transects the segment, and reconnects the halves end to end, thereby doubling the length of bowel and helping motility. Inclusion criteria include an intestinal diameter >3 cm; length of residual small bowel >40 cm with ≥20 cm of dilated small bowel; PN dependence; and an absence of liver disease, Crohn disease, and radiation enteropathy. In one study, 14 of 16 children were successfully weaned off PN using this procedure; anastomotic stenoses, a major complication, occurred in approximately 10% of patients.[11][29][30]
The STEP procedure involves applying linear staples along the small bowel in alternating and opposite directions in order to incompletely divide the dilated intestine. This has the same effect as the Bianchi procedure, but has the advantage of avoiding postoperative stricture formation.[31]
No randomized controlled trials have compared the Bianchi and STEP procedures; therefore, it is not clear which procedure is superior, although STEP is technically less challenging for surgeons to perform.
Patients with SBS and dilated nonfunctional segments of bowel may have bacterial overgrowth in the bowel. If persistent, this should be treated before performing these procedures.
Oral intake
Hydration
When thirsty, oral rehydration solution (ORS) should be encouraged in all patients instead of water, juice, or sports drinks.[10][32][33] ORS was developed by the WHO, and is composed of 2.5 g NaCl, 1.5 g KCl, 2.5 g sodium bicarbonate, and 1.5 g sucrose in 1 liter of water. This composition takes advantage of the intestinal sodium-glucose cotransport mechanism to maximize water absorption. Commercial preparations in powdered or ready-to-use forms are available. Urine output should be maintained at a minimum of 1000 mL in 24 hours.
ORS that is specifically formulated to suit certain patients may need to be prepared, according to local protocols: for example, a solution that contains no potassium for a patient with, or at risk of, hyperkalemia.
Dietary instruction
Patients must be encouraged to eat 2 to 3 times more calories than they did prior to acquiring SBS. This may produce further diarrhea, but helps with intestinal adaptation and weaning from PN.
Foods containing lactose are a rich source of calcium and should be encouraged unless the patient is known to be lactose intolerant, or a massive jejunal resection has been performed.[34]
Patients with an ileal resection have bile salt and fat malabsorption, and magnesium, vitamin B12, and calcium deficiencies. Fat-soluble vitamin deficiency (A, D, E, K) may also develop as a result of fat malabsorption. Although fat is an energy-dense macronutrient, it may cause diarrhea in patients with a colon in continuity. Medium-chain triglycerides (MCT) can be supplemented as a fat source because they are absorbed directly into the portal circulation, without the need for bile salt binding from the stomach, small bowel, and colon; however, they have poor taste and a low smoking point when used in cooking. MCT do not supply essential fatty acids.
A small body of evidence has shown that peptide-based enteral formulas are not superior to other formulas and should therefore not be routinely prescribed.[35][36]
Prescription of oral medications
Oral medications will be absorbed unpredictably in each patient, and alternatives to oral dosing should be sought.
Sublingual medications are preferred.
Intravenous formulations are usually avoided if possible, as frequent catheter access can predispose to infections.
Serum drug-concentration monitoring should be carried out whenever possible to ensure that the dose is not toxic or subtherapeutic.[33]
Management of fluid loss
Patients with SBS have two major sources of fluid loss. The first is gastric acid hypersecretion stimulated by hypergastrinemia. The second is diarrhea, which is multifactorial.
Acid reduction: a proton-pump inhibitor (PPI), such as omeprazole or lansoprazole, is required for the first 6 months to reduce the temporary compensatory gastric hypersecretion that occurs following extensive GI surgery.[2][4][37][38][39][40][41] Less-extensive surgery, such as small segmental resections for Crohn disease, may not cause gastric hypersecretion, and PPI therapy is not required for these cases. A serum gastrin concentration can be used to guide the need for PPI therapy. PPIs can induce diarrhea in some patients, so monitoring diarrheal volumes before and after the commencement of PPI treatment is important.
Diarrhea control: loperamide and diphenoxylate/atropine are first-line agents for the management of diarrhea.[10] Opioids such as codeine or tincture of opium are second line.[2] Third-line alternatives include the bile-acid binding drugs cholestyramine and colestipol, which help prevent diarrhea caused by unabsorbed bile acids, but they may enhance fat-soluble vitamin and medication malabsorption and increase diarrhea. Octreotide can control diarrhea by slowing intestinal transit and increasing water and sodium absorption, but can induce cholelithiasis, and inhibits intestinal adaptation, prolonging the time needed on PN.[42][43] Clonidine can reduce diarrheal volume in patients with residual colon in continuity due to its effects on chloride absorption, but can produce significant side effects of hypotension, and central effects such as drowsiness.[44]
Electrolyte/micronutrient monitoring and replacement
All patients require electrolyte/micronutrient monitoring and replacement.
Calcium supplementation is indicated in all patients. Potassium, magnesium, bicarbonate, phosphorus, or any deficient vitamins and nutrients should be supplemented as needed. Caution must be used with oral magnesium supplements as they can induce diarrhea and worsen absorption. Magnesium gluconate may cause less diarrhea than oxide, sulfate, or citrate salts. Lifelong management of vitamin B12 and fat malabsorption is required in patients with greater than 60 cm of terminal ileum resection, as intestinal adaptation cannot compensate for the unique functions of the terminal ileum.
Levels need to be frequently checked during supplementation as absorption is different for every patient. [Figure caption and citation for the preceding image starts]: Management of short bowel syndrome. MCT, medium-chain triglycerides; PPI, proton-pump inhibitor; PN, parenteral nutritionAdapted from Buchman AL, et al. Gastroenterology. 2003;124:1111-1134. Used with permission. [Citation ends].
Use of this content is subject to our disclaimer