Intestinal Failure

Pediatric Surgery
Discussion with Dr. Brad W. Warner about intestinal failure

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What is intestinal failure?

  • An umbrella term for when the small bowel is unable to digest and absorb an adequate amount of nutrients to sustain a patient through enteral means alone.
  • Short gut is a component of intestinal failure where significant intestinal length has been removed (or is missing
  • Intestinal failure may also be due to dysmotility (e.g. Hirschsprung’s disease) or mucosal disease, which are not considered short gut syndrome.
 Significance of bowel length
  • Fetal intestinal length doubles in length during the last trimester. This is significant because a premature baby who undergoes a significant bowel resection has much greater ability to adapt and is less likely to develop IF.
  • For a neonate, presence of the ileocecal valve and 10-15 cm of small bowel may be adequate.
  • Without the colon and ileocecal valve, at least 15-20 cm would be necessary for a neonate.
  • In adults, the 5-10 year mortality for patients with 50 cm of small bowel is 40%.
     Prognosis of patients with short gut requiring TPN
    • 25% die, 25% require small bowel +/- liver transplant, and 50% wean from TPN.
       Causes of death in patients with intestinal failure
      • Liver failure, typically secondary to TPN hepatotoxicity
      • Sepsis (associated with central line infection and bacterial overgrowth in the small bowel)
      • Variceal bleeds associated with TPN-related cirrhosis and portal hypertension
      • Loss of venous access
         Small bowel transplant candidacy
        • At least some degree of intestinal adaption will occur after small bowel resection, and patients should thus be given time for this to occur. This may take up to 2 years.
        • The goal during this period should be aggressively weaning parenteral nutrition and attempting enteral nutrition.
        • The contraindications to continuing this approach are multiple line-infections, rising bilirubin, and stool exceeding 40 mL/kg/day.
           Causes of short gut syndrome
          • The most common causes of short gut syndrome are necrotizing entercolitis, gastroschisis, midgut volvulus, and intestinal atresias.
          • Less common causes are trauma and inflammatory bowel disease
             Medical management of short gut syndrome
            • Start with TPN providing a goal of 100-120 kcal/kg/day (50% glucose and the remainder fat and protein).
            • The goal for protein is 2-3 g/kg/day and for fat is 2-3 g/kg/day.
            • Enteral feeding (preferably using breast milk in neonates) should be started as soon as feasible (e.g. after return of bowel function in the post-operative patient). Slow (1 mL/hr), continuous enteral feeds are favored over bolus feeds by Dr. Warner. This should be slowly increased. On the other hand, oral feeds have the advantage of stimulating release of more GI hormones.
            • In patients who are not growing, and thus require increased nutrient administration, enteral nutrition should be increased first (up to the aforementioned limit of stool output) prior to increasing TPN.
            • The patient’s weight should be closely monitored, with a goal of gaining 20-30 g/day. Lack of weight gain, or weight loss, is an indication for increasing the number of parenteral calories delivered. However, enteral feeds should continue unless stool output becomes excessive.
               Primary prevention of TPN cholestasis
              • Hyperbilirubinemia is secondary to TPN cholestasis.
              • Lipid reduction should be attempted by reducing parenteral fat reduction to 1g/kg/day given 2-3 days per week. Reduced fat intake may be detrimental to neurodevelopment.
              • An alternative is use of a lipid formulation high in omega-3 fatty acids (Omegaven), as opposed to convention lipid formulations which are based on soybean oil and are high in omega-6 fatty acids. The omega-3 formulations do not contain sufficient amounts of essential fatty acids.
              • Smoflipid (Fresenius Kabi USA, Warrendale, PA) contains soybean oil (which provides the essential fatty acids), medium chain triglycerides, olive oil, and fish oil. This formulation may be more physiologic.
                  Continuous enteral feeding
                • Start at 1 mL/hr. Double this in a few days. Increase by 50-100% after another few days. This should be guided by stool output.
                • Once the stool output has increased too much, enteral feed rate can be held and the patient given at least a few weeks to allow for continued intestinal adaptation.
                   Choice of enteral formula
                  • For neonates, breast milk is preferred, particularly due to its containing essential nutrients as well as growth factors and oligosaccharides.
                  • For older patients, elemental formulas are not typically used. While these formulas may be more easily absorbed, more complex formulas may actually better stimulate intestinal adaptation.
                     Surgical management of intestinal failure
                    • In patients who have not yet reached the 1-2 year mark (and thus have continued for potential further intestinal adaptation), an indication for surgical intervention may be worsening tolerance of enteral nutrition.
                    • Other indications include sepsis associated with dilated small bowel loops (and bacterial overgrowth), as well as worsening hyperbilirubinemia.
                       Surgical workup
                      • Start with plain abdominal radiograph.
                      • Next is contrast enema and upper gastrointestinal series with small bowel follow through with transit time. These help to rule out a "simple” cause of failure to progress, such as adhesive bowel disease.
                      • Dilated bowel loops (greater than 4-5 cm diameter) are an indication for surgical bowel-lengthening procedure.
                          Surgical options
                        • Start with laparotomy.
                        • If the patient has over 100 cm of small bowel, it is unlikely that a lengthening procedure will be beneficial to this patient, particularly if the bowel is not significantly dilated. These patients are more likely to have a motility disorder or a mucosal enteropathy.
                        • If there is less than 100 cm of small bowel, and particularly if it is dilated (greater than 4-5 cm in diameter), the patient is more likely to benefit from a bowel lengthening surgery.
                        • The Bianchi procedure and serial transverse enteroplasty procedure (STEP) are common lengthening options, with STEP being more popular.
                            Bianchi procedure
                          • Takes advantage of the fact that there is a bifurcation of the blood supply to the bowel at the mesenteric surface of the bowel.
                          • Essentially doubles the length of the bowel.
                          • The procedure is started proximal to the dilation.
                             STEP Procedure
                            • Partial, transverse transection of the bowel on alternating sides of the bowel.
                            • Serves to reduce the caliber and increase the effective length of the intestine.
                            • Technically easier to perform than the Bianchi procedure.
                            • The bowel may dilate again following a STEP procedure and these patients may require re-do STEP procedure.
                            • A STEP may be performed on bowel which has previously undergone Bianchi procedure, but the opposite is not true.
                            • Patients who undergo STEP may have post-operative motility problems permanently. Consequently, Bianchi may be a better, primary lengthening procedure.
                               Bianchi Procedure Pearls
                              • When dividing the bowel, ensure the stapler is in the proper plane and oriented longitudinally. Make sure to stay in the midline between the vessels supplying the bowel.
                              • Avoid kinking of the bowel when performing the anastomosis.
                              • Ensure that the peristaltic segments are oriented properly.
                                Role of tapering
                                • Tapering may be indicated in patients who have dilated bowel and at least 90-100 cm of intestinal length.
                                • Patients with adequate intestinal length and dilation should be tapered.
                                    Secondary prevention of TPN cholestasis
                                  • Bile salts may be given to improve bile flow.
                                  • Changing lipid composition (as discussed earlier).
                                  • Increasing the ratio of feeds given enterally.
                                  • Cholecystokinin has not been shown to improve TPN cholestasis.
                                      Medical management of intestinal bacterial overgrowth
                                    • There are no therapies with strong evidence supporting them.
                                    • Oral antibiotics (often ciprofloxacin and/or metronidazole)
                                    • Probiotics
                                    • Prebiotics – Nutrients for the "good” bacteria
                                    • Fecal transplantation
                                    • Best treatment is addressing the underlying cause, which is dysmotility and dilated bowel.
                                       Role of growth factors
                                      • A glucagon-like peptide (GLP-2) analogue, teduglutide (Gattex, Shire, Dublin, Ireland), has been tested in adults in randomized prospective controlled trials and allowed for a significant reduction in TPN requirement. This drug is not approved for children in the United States.
                                      • There is a concern that this drug may pose a malignancy risk, particularly in children.
                                      • In animal studies, other growth factors have demonstrated improved intestinal adaption to decreased intestinal length. These factors include epidermal growth factor (EGF), heparin binding EGF, multiple interleukins, growth hormone, and glutamine.
                                         Intestinal transplant
                                        • Survival is 50-60% at 5 years. One year survival is around 70-80%.
                                        • Difficult balance between graft versus host disease and side-effects of immunosuppressive drugs.
                                        • Patients who are stable and not experiencing TPN cholestasis should not under intestinal transplant exclusively to get them off TPN due to the risks of transplant.
                                           
                                           Management of central line-associated infections
                                          • Ethanol lock significantly reduces the number of episodes of sepsis associated with Broviac catheters.
                                          • This is used prophylactically in patients on home TPN.

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