Small Intestine: Intestinal Failure

Intestinal Failure

Definition

  • Inability of the Gut to Absorb the Necessary Water, Nutrients & Electrolytes to Sustain Life
  • In the Past was Uniformly Lethal, Now Much Improved Prognosis with 90% Long-Term Survival

Causes

  • Short Gut Syndrome (Most Common Cause)
    • 80% of Adults
    • 50% of Peds
  • Adult Causes:
    • Mesenteric Ischemia
    • Crohn’s Disease
    • Volvulus
    • Chronic Intestinal Pseudo-Obstruction
    • Familial Polyposis
    • Tumors
    • Radiation Enteritis
    • Bariatric Surgery
  • Pediatric Causes:
    • Intestinal Atresia
    • Necrotizing Enterocolitis
    • Gastroschisis
    • Volvulus
    • Hirschsprung’s Disease with Significant Involvement of Small Intestine
    • Microvillus Atrophy
    • Autoimmune Enteropathy
    • Intestinal Epithelial Dysplasia

Short Gut Syndrome (SGS) (Short Bowel Syndrome/SBS)

  • Definition: Intestinal Failure After Extensive Loss of Small Intestine
  • Defined by Function, Not Length
  • Most Often from One Single Large Resection (75%), Rather than Multiple Sequential Surgeries

Bowel Length

  • Residual Small Bowel < 180 cm are at Risk
    • Decreased Risk: Functional Ileocecal Valve or ≥ 50% of Colon
    • Jejunum Resection Better Tolerated than Ileum
  • General Requirements to Survive off TPN:
    • 75 cm Small Bowel without Competent Ileocecal Valve
    • 50 cm Small Bowel with Competent Ileocecal Valve

Intestinal Adaptation

  • Bowel Adapts Over 1-2 Years After Loss
  • Most Prominent Throughout Ileum
  • Structural Adaptations:
    • Remnant Bowel Dilation & Elongation
    • Villus Lengthening
    • Microvillus Expansion
    • Crypt Cell Hyperplasia
  • Functional Adaptations:
    • Increased Absorption/Permeability
    • Increased Gut Hormonal Secretion
    • Slowed Rate of Gut Transit
    • Gut Microbiota Changes

Presentation

  • Symptoms:
    • Fatigue
    • Weight Loss
    • Nausea & Vomiting
    • Diarrhea
    • Steatorrhea
  • Complications:
    • Nutritional Deficiencies
    • Esophagitis & Peptic Ulcers
    • Cholestasis & Cholelithiasis
    • Osteomalacia
    • Nephrolithiasis

Diagnosis

  • Clinical Diagnosis
  • Supportive Tests:
    • Labs – Electrolytes, Vitamin Levels & Albumin
    • D-Xylose Absorption Test
      • D-Xylose (Easily Absorbed Monosaccharide) Given Orally & Urine Level is Measured
      • Low Urine Level Indicated Malabsorption
    • Sudan III Stain Test
      • Sudan Dye (High Affinity for Lipids) Used on Stool Sample to Determine Level of Fecal Fat
      • High Level of Fecal Fat Indicates Steatorrhea
    • Schilling Test
      • Vitamin B12 Given Orally & Urine Level is Measured
        • Multiple Stages with Intrinsic Factor, ABX & Pancreatic Enzymes
      • Low Urine Level Indicates Malabsorption
    • Serum Citrulline Test
      • Citrulline (Nonessential Amino Acid Produced by Enterocytes) Blood Level Measured
      • Strong Marker for Enterocyte Mass & Low Level (< 20 μmol/L) Associated with Intestinal Failure

Intestinal Failure – Management

Initial Treatment

  • Early Enteral Feeding – Vital for Intestinal Function & Adaptation
  • Electrolyte Management & Parenteral Nutrition as Indicated
  • PPI or H2 Blocker – Prevent Gastric Hypersecretion
  • Antidiarrheal Medications as Needed

Pharmacologic Adjuncts

  • GLP-1 Analog (Liraglutide)
    • Supports Intestinal Epithelium
  • GLP-2 Analog (Teduglutide)
    • Supports Intestinal Epithelium & Adaptive Response
    • Promotes Weaning from Parenteral Nutrition
  • Growth Hormone & Glutamine (Enterocyte Energy Source)
    • Improves Intestinal Absorption
    • Glutamine Alone Does Not Appear to Benefit
  • Octreotide
    • Increases Transit Time & Reduces Fluid Loss

Surgical Management

  • Indication: If Fails to Wean Off Parenteral Nutrition
  • Restore Intestinal Continuity if Any Segments Were Previously Bypassed or Unused
  • If Intestine Lengthening Necessary: Serial Transverse Enteroplasty
    • Requires Dilated Bowel of Adequate Length
    • If Not Dilated May Consider Segmental Reversal (Interposition of Reversed Segments to Slow Transit)
  • Intestinal Transplant
    • Indications:
      • Lifelong Parenteral Nutrition Dependent with Irreversible Parenteral Nutation Complications
      • Lifelong Parenteral Nutrition Dependent with Failure to Manage Hydration/Nutrition
    • Definitions:
      • Intestinal Transplant – Can Include Intestines, Liver & Multi-Visceral Transplants
      • Isolated Intestinal Transplant – Only Intestines Transplanted
    • Exact Operation Tailored to the Patient
    • Liver-Inclusive Transplant Has Improved Survival Over Isolated Intestine Transplant Due to Immunologic Tolerance from the Liver

Autologous Intestinal Reconstruction Surgery (AIRS)

  • Requires Dilated Bowel of Adequate Length
  • Serial Transverse Enteroplasty (STEP Procedure)
    • Fire Transverse Staple Loads Partially Across the Lumen Alternating from the Mesenteric & Antimesenteric Edges of Dilated Bowel
  • Longitudinal Intestinal Lengthening & Tailoring (LILT/Bianchi Procedure)
    • Vascular Tunnel Created Between the Mesenteric Vessels & Longitudinal Division of the Intestine into Two Separate Pieces Which are Then Anastomosed
    • The First Original Intestinal Lengthening Procedure
    • Fallen Out of Favor – More Complex & Risk for Compromised Blood Flow

Serial Transverse Enteroplasty (STEP) 1

References

  1. Wester T, Borg H, Naji H, Stenström P, Westbacke G, Lilja HE. Serial transverse enteroplasty to facilitate enteral autonomy in selected children with short bowel syndrome. Br J Surg. 2014 Sep;101(10):1329-33. (License: CC BY-NC-ND-3.0)