Short Bowel Syndrome, SBS (Short Gut) and intestinal failure

Definitions

• Malabsoptive state due to resection of the small intestine, congenital defect or disease associated loss of absoptive capacity
• Refers to malabsoption of macro and micro nutrients, not a specific length of intestine

• GI function that is inadequate to maintain adequate hydration, nutrient, and growth status without IV or enteral supplementation
• Dependence on supplemental parenteral support for a minimum of 60 days within a 74-consecutive day interval - The american society of Enteral and Parenteral Nutrition

• Response of the GI tract to massive resection
• Changes in the GI lumen/mucosa which increase absoptive capacity over time

• The state where a patient can achieve appropriate growth without perenteral nutrition or IV support. (May still need Tube feeds)
• Changes include: lengthening and dilation of bowel, lengthening ov the villi and deepening of the crypts, increased synthesis of digestive enzymes, proliferation and apoptosis of enterocytes, changes in gene expression
• Factors which improve chances of achieving enteral autonomy:
  
• Longer residual length, preservation of IC valve
• Residual small bowel length of >40 cm is associated with enteral autonomy.
• Small bowel continuity with >50% residual colon is associated with enteral autonomy.
• Prompt initiation and advancement of enteral feeding promotes adaptation.
• NEC has more favorable outcomes than gastroschisis, atresias, and others causes
• -Patients at centers that emphasize rehabilitation and provides time and support to optimize intestinal adaptation, typically have a better chance at achieving autonomy (vs early referral to intestinal transplant center)

• Probability of weaning from PN by 24mo was 96% in infants with >50cm of residual small bowel (36% in infants with <50cm)
• Institution and individual depedent: in some centers 48% of patients with <20cm residual sm bowel achieve enteral autonomy in <2yrs
• Section remaining may affect outcomes as well: ileal remnant may do better than jejunal remnant

• Ileum can compensate for absorption of Protein, carbs, and fats after loss of jejunem (deodenum cannot compensate for loss of ileum as well)
• Ileum is better at absorbing fluids. Pts with Loss of ileum can have recurrent watery diarrhea
• Absorption of B12 and Bile salts (needed to absorb fats and fat soluble vitamins) Lake of terminal ileum can lead to diarrhea from malabsorbed bile salts (bile acid diarrhea) or from inability to absorb fats -steatorrhea
• Ileal Brake: unabsorbed lipids reaching the ileum delay gastric emptying (slower release to small bowel may enhance absorption)
• IC Valve: loss of IC valve associated with lower chance of achieving enteral autonomy

• NEC: 26%
• Gastroschisis: 16%
• Intestinal Atresias: 10%
• Volvulus: 9%
• Hirshprungs: 4%
• Other: 18%

Management

• Losses of fluids and electrolytes
• Malabsorption of Macronutrients
• Malabsorption of vitamins/minerals
• Poor weight gain / growth
• Dysmotility (esp gastroschisis patients)

• IFALD: intestinal failure-associated liver disease
• SIBO
• Feeding difficulties/disorders

• Management of fluids, nutrition, and electrolytes via TPN
• Lab monitoring (see labs below) also monitor for IFALD
• Fluid losses can be common early on - strict I&O's; replacement of enteral losses is warranted - monitor for high-output ostomy or stool losses
• Acid suppression: Gastric acid hypersecretion often seen after surgery. (alters pH affects enzymes, meds, fat absorption) Start with H2 blocker, if effective continue for several months. If ineffective, start PPI. Attempt to wean after 2-3months

• Early initiation of Enteral feeds supports intestinal adaptation (once stable, often a few days s/p surgery) Essential to prevent intestinal atrophy
• Continuous Trophic feeds via NG or gastrostomy tube (if dysmotility or poor gastric emptying, consider post-pyloric feeds)
• Human milk is optimal (Breast is best), if unable to start breastmilk, start Elemental formula. Older children can tolerate intact protein or blenderized food formulas
• Offer small volume oral feedings at appropriate intervals to allow for normal development and avoidance of oral-aversion

• Advancement depends on amount of residual intestine, patients age, size, growth
• Work with nutrition/dietician for target and Speech Pathologist for oral feeding support
• Due to malabsorption, plan for 30-70% increase from TPN energy needs

• Infants typically benefit from higher fat content (40-50% of total energy intake)
• LCT's may help stimulate intestinal adaptation
• MCT's are better absorbed as they directly cross the enterocyte membrane (do not require lymphatic absorption)
• Ratio of 40% MCT to 60% LCT is recommended

• Triene/tetraene ratio >0.05
• Increased risk when weaning from PN
• Check fatty acid labs 1-2mo after weaning and annually
• Sx: poor growth, dry scale/ rash, thrombocytopenia, poor wound healing, increased infections
• Tx: supplement with oils high in essential fatty acids (canola, walnut, flaxseed)

• Transition to bolus when patient is taking 1/2 of total energy requirements from enteral feeds and remainder from PN
• Often times will continue with continuous overnight feeds

**Lab Monitoring

• BMP, Mg, Phos, Albumin, Prealbumin, Triglycerides (on initiation, then weekly, then with changes. Once stable can check q1-3mo)
• CBC / Iron studies (q1-3mo or as clinically indicated)
• Hepatic function (when PN initiated, qwk until stable, then q1-3mo)
• Cu, Zn, Selenium, with CRP (30days after initiation of PN and then q6mo - unless making changes, then q2-3mo)
• PT, INR (q6mo)
• ADEK Vitamins (Annually, q3-6mo if deficiency, liver Dz, or supplementation) D = 25-OHVitD, E = alpha-tocopherol
• B12 (Annually)
• Essential fatty acid panel (q3-6mo if total fat intake <g/kg/day for over 10-14 days)
• Aluminum, carnitine profile (30 days after starting PN , then q6mo)
• Alpha-fetoprotein (annually for cirrhotic patients w/ h/o IFALD)
• Chromium, Manganese (Annually - more often if concern for glycemic control
• Urine Na (q6mo, more often if poor weight gain)

• BMP, Mg, Phos, Alb, prealbumin, TG's, CBC, Iron Panel, PT/INR, Cu, Zn, Selenium, CRP, ADEK vitamins, B12,

• Hepatic Panel and alph-fetoprotein if h/o IFALD
• Urine NA is poor wt gain, high ostomy output or NaCl supplementation

Troubleshooting

Surgical Interventions

• 2 procedures
• STEP Procedure (serial transverse enteroplasty procedure): no anastomoses, can be performed with Bianchi, can be repeated
• Bianchi Procedure (longitudinal intestinal lengthening and tailoring (LILT): requires multiple anastomoses