Short Bowel Syndrome Causes and Management

Short bowel syndrome definition, causes, diagnosis and treatment

1. Short Bowel Syndrome(SBS) DR KULDIP PATIL Assintant Professor

2. Outline Anatomy Physiology Definition Pathophysiology Classification(including etiology) Clinical Presentation Workup Treatment

3. Anatomy Length of small gut* Neonate 250 cm Adult Average 600 cm (Range 260- 800 cm) Short Gut Syndrome 200 cm viable (Adult) >50 %-80% lost Lifelong TPN Dependence (Minimal gut length required for life) Adult With intact colon 60 cm Without colon 100 cm Infant With ileocecal valve 11 cm Without ileoceal valve 12-25 cm __________________________________________________________________ *As a consequence, the infant and the young child have a favorable long-term prognosis compared to an adult in regards to potential intestinal growth after intestinal resection

4. Physiology Jejunum Ileum Villi Long Shorter Absorptive surface area Large Less Tight Junction Relatively large  epithelium more porous to larger molecules free and rapid flux of water and electrolytes Tighter permitting less flux of water and electrolytes from the vascular space into the intestinal lumen Water absorption Less effective More efficient Absorption Carbohydrates, proteins, fat, vitamins (iron-duodenum) Bile acids, vitamin B-12 GI hormones that affect intestinal motility enteroglucagon and peptide YY Etymology: Duodenum (Latin: duodēnum  Twelve ) (duodenum is 12 fingerbreadth long) Jejunum ( Latin: jejunus  fasting )( because it was usually found to be empty after death ). Ileum ( Greek: eilein  to twist up tightly)

5. Physiology Proximal jejunal resection is better tolerated than distal ileum resection

6. Definition Clinically defined by malabsorption , diarrhea, steatorrhea , fluid and electrolyte disturbances, and malnutrition due to ≥ 50 % (viable gut <200 cm) of structural or functional loss of small gut.

7. Pathophysiology

8. Pathophysiology Loss of ileocecal valve transit time is faster, and loss of fluid and nutrients is greater C olonic bacteria colonize the small bowel, worsening diarrhea and nutrient loss.

9. Pathophysiology Preservation of the colon MERITS DEMERITS colonic water absorption could be increased to as much as five times its normal capacity following small bowel resection increase incidence of urinary calcium oxalate stone formation (Oxalate is normally bound by calcium in the small bowel and thus is insoluble when it reaches the colon. After massive enterectomy , much of this calcium is bound by free intraluminal fats) Colonic bacteria  metabolize undigested carbohydrates(starch & fibres ) into short-chain fatty acids, such as butyrate, propionate, and acetate. (up to 500 kcal/day) small intestinal bacterial overgrowth. ( in absence of ileocecal valve)

10. Natural History ( 3 Phases) Acute Phase Adaption Phase Maintenance Phase

11. Acute Phase Starts immediately after bowel resection and lasts 1-4 months Ostomy output of greater than 5 L/day (as high as 6-8 L/day) Life-threatening dehydration and electrolyte imbalances Extremely poor absorption of all nutrients Development of hypergastrinemia and hyperbilirubinemia

12. Adaption Phase Enterocyte hyperplasia + villous hyperplasia + increased crypt depth  increased surface area ; intestinal dilatation and lengthening  increased capacity/Low transit time(reduction in volume and frequency of bowel movements) _______________________________________________________ Begins within 48 hours of resection and lasts up to 1-2 years ~ 90 % of the bowel adaptation takes place during this phase Luminal nutrition is essential for adaptation and should be initiated as early as possible; parenteral nutrition is also essential throughout this period

13. Maintenance Phase Absorptive capacity of the intestine is at its maximum

14. Classification Congenital versus Acquired CONGENITAL ACQUIRED Congenital Short Small Bowel * NEONATAL PERIOD ADULT Necrotizing enterocolitis Crohn disease Intestinal atresias radiation enteritis Intestinal volvulus mesenteric vascular accidents OLDER INFANTS and CHILDREN Trauma Intussusception with ischemic small-intestinal injury recurrent intestinal obstruction * Also associated with g astroschisis , omphalocele and meconium peritonitis.

15. Classification Structural versus functional STRUCTURAL FUNCTIONAL Any insult leading to  < 200 cm or loss of ≥ 50% of viable small bowel  Increased risk of developing SBS ( NOT ALWAYS) PREDISPOSING FACTORS premorbid length of small bowel segment of intestine that is lost, Age of the patient (infant tolerate better) Remaining length of small bowel and colon, Presence or absence of the ileocecal valve Length maintained BUT function is lost For example: Radiation Enteritis Cloacal Extrophy

16. Classification SBS due to proximal jejunal resection versus SBS due to distal ileum resection

17. Clinical Presentation Diarrhea ± steatorrhea dehydration and electrolytes disturbances Significant weight loss, fatigue, malaise, and lethargy Malnutrition Mineral deficiencies ( f olate , iron , calcium , magnesium , zinc) Vitamins deficiencies (A,D, E, K , B complex esp B12) Macro- nutrient deficiencies ( CHO,Protein,fat )

18. Clinical Presentation Recurrent bacterial enteritis Stones and related problems Gall stones due to altered bile metabolism Renal stones due to high oxalate Vomiting, bloating, GERD, gastric ulceration Failure to thrive Drug toxicities Bowel Obstruction (potential complication)

19. Clinical Presentation TPN related issues Line sepsis and fulminant liver failure Enteral Feeding related issues gastrostomy or nasogastric tube issues

20. Clinical Presentation During the physical examination, pay close attention to these clinical signs Vitals State of hydration State of nutrition, as measured by a patient's weight for height and anthropometric measurements Signs of sepsis Form of nutritional therapy used in the patient ( eg , central line access or enteral access) Specific clinical signs of nutritional deficiency Signs of liver disease

21. Workup Hematological and Biochemical investigations Radiological investigations Microbiological investigations Histopathological investigations Miscellaneous

22. Workup Hematological and Biochemical investigations CBC Anemia (MCH, MCHC, MCV) Thrombocytosis/thrombocytopenia Hyper segmented neutrophils Albumin (half life 21 days) good indicator of hepatic protein synthesis indicator of overall nutritional status Prealbumin ( 3-5 days) indicator of acute nutritional status monitor the efficacy of nutrition support regimens AST/ALT TPN induced liver failure Electrolytes (Na, K, Cl , Zn, Ca , Mg,Cr , Se, PO 4 -3 ) TPN monitoring BUN Renal reserve Dehydration(>20:1) Overfed with protein Vitamins Level Coagulation Profile Deranged Liver function

23. Workup Hematological and Biochemical investigations Frequency* Electrolytes, BUN, creatinine , calcium, magnesium, phosphorous Twice weekly Comprehensive metabolic panel, CBC, triglycerides, cholesterol Weekly Folate , vitamin B-12, vitamin E, copper, zinc, selenium Monthly *both in initial phase and the late period or at the time of presentation for instability

24. Workup Radiological investigations Plain Chest X-ray Post CV line insertion Plain Abdominal X-ray Suspected bowel obstruction Barium imaging of the bowel Abdominal USG fungal balls in the kidney (sepsis) Renal Stones and related problems Gall stones and related problems Liver failure (spleen, ascites, liver texture, Portal vein flow-Duplex) CT-Abdomen identify persistent sepsis Potential Liver/Bowel transplant Angiography

25. Workup Microbiological investigations Blood cultures (both central and peripheral sites) Urinalysis and blood culture (specifically to search for fungal infection ) CV line tip SOURCE of SEPSIS: Line Sepsis, Gut mucosal atrophy  bacterial translocation Skin flora penetration

26. Workup Histopathological investigations Liver biopsy(rare) TPN related liver problems

27. Workup Miscellaneous Upper GI endoscopy to assess for peptic ulcer disease and possible signs of liver disease e.g . esophageal varices , hypertensive gastropathy Dual radiographic absorptiometry Bone density estimation in Metabolic Bone Disease

28. Treatment (aggressive MULTI DISCPLINARY APPROACH ) MEDICAL CARE Nutrition Early aggressive enteral feeding Parenteral nutrition Aggressive Hydration Electrolytes r eplacement Acid reducing agents(PPI, H 2 blocker) Antibiotics for bacterial overgrowth Bile salt chelators ( Cholestyramine ) Psychosocial support SURGICAL CARE Nontransplant surgery Small bowel ± liver transplantation

29. Nutrition

30. Common Concerns with enteral nutrition Fat Intolerance (increase in stool output with the appearance of fecal-reducing substances) LCFA(high energy density) better tolerated carbohydrates parenterally and providing fats enterally Continuous enteral feeds is better tolerated than bolus feeds High stool volume and frequency DON’T STOP or substantially lower the volume and frequency of feeds in response to changes in stool volume (as long as it does not compromise the child's hydration, acid base balance, and serum electrolyte levels) RATIONALE: Most of fluid and electrolytes disturbances can be corrected by IV formula Decreasing amount of carbohydrates within the enteral feeds decreasing the volume and concentration of feeds Avoid fibers GERD, Vomiting Decreasing either the volume or rate of feeds

31. Early Aggressive Enteral Nutrition Elemental/modular formulas RATIONALE CHO mixture of monosaccharides and polysaccharides is preferred to disaccharides in order to limit osmotic load Fat Medium-chain triglycerides (MCT) readily absorbed in the stomach and proximal small bowel  improving fat and total energy absorption long-chain triglycerides (LCT) prevent essential fatty acid deficiency 10% of the patient's energy needs trophic effect on the intestinal mucosa Protein Oligopeptide formulas are better absorbed than elemental amino acid formulas di- tripeptide absorption exceeds that of amino acids. Concentration either one-fourth or one-half strength increasing in volume before increasing energy density/conc.

32. Factors predictive of achieving independence from TPN Residual Bowel length Intact colon Intact ileocecal valve Healthy (versus diseased) residual small gut Jejunal resection (versus ileal resection) Bacterial overgrowth Dysmotility Teduglutide enhancement or restoration of the structural and functional integrity of the remaining intestine SERUM CITRULLINE LEVEL

33. Serum Citrulline * in SBS α-amino acid key intermediate in the urea cycle. Citrullinemia is correlated to small bowel length and to net digestive absorption of fat Cuff-off value of 20 µ mol /l classified short bowel patients with permanent intestinal failure with high sensitivity (92%), specificity (90%), positive predictive value (95%), and negative value (86 %); more reliable indicator than anatomic variables to separate transient as opposed to permanent intestinal failure. __________________________________________________________________ *Etymology: Latin citrullus = watermelon (from which it was first isolated)

34. postabsorptive plasma citrulline concentration surrogate marker for bowel length and function . past the 2-year adaptive period, a powerful independent indicator allowing distinction of transient from permanent intestinal failure.

35. Micronutrients Supplementation Rationale/Route Water soluble Vit A, Vit D, and Vit E In case of significant steatorrhea (IV) Calcium Oral route for bone mineralization and growth (Dual energy x-ray absorptiometry (DEXA) scan) Vitamin K Not required ( synthesize by enteric bacteria) (monitored by PT time) deficiency of water-soluble vitamins is rare except Vitamin B 12 Vitamin B 12 IV on a monthly basis or as a nasal gel

36. Micronutrients IV iron infusion bacterial overgrowth or malabsorption Zinc secondary to increased fecal losses manganese and selenium pharmacologic doses as required. Copper associated with anemia and cardiomyopathy

37. Bacterial overgrowth Predisposing factor Absence of ileocecal valve Dysmotilty of residual gut Manifestations deconjugation of bile salts and depletion of bile salt stores Vitamin B12 deficiency  Pernicious anemia carbohydrate malabsorption  worsening of osmotic diarrhea metabolic lactic acidosis  CNS disturbances Dehydration Treatment metronidazole alternating with either kanamycin or oral gentamicin

38. Codeine and loperamide to slow intestinal transit time DEMERIT: leads to bacterial overgrowth Octreotide Rarely used for concerns of the effect on growth and worsening cholestatic liver disease Glutamine and CCK No selective advantage

39. Surgical Care Diverting ileostomy In case of malfunctional colon Central Venous line insertion PEG (percutaneous endoscopic gastrotomy ) Reversal of stoma To capitalize on absorptive capacity of all residual gut

40. Surgical Care To slow transit time* Segmental reversal of small bowel Interposition of segment of colon between segments of small gut Construction of small gut valves Retrograde electrical pacing of small gut To increase gut length/area LILT ( Longitudinal Intestinal Lengthening and tailoring) or Bianchi procedure STEP (Serial transerve enteroplasty procedure)

41. LILT (Bianchi 1980 ) Procedure Separation of dual blood supply Longitudinal division Iso -peristaltic end-to-end anastomosis

42. STEP Serial applications of an intestinal stapling device, with firings oriented perpendicular to long axis of intestine By 2013, amongst 111 patients operated 47 % cases had achieved enteral autonomy by 21 months. 1 st performed in 2003 on 2-year-old baby who had been born with gastroschisis

43. Intestinal Transplantation Indications Life threatening complications due to intestinal failure or long term TPN Impending or overt liver failure Thrombosis of major central veins Frequent episodes of catheter-related sepsis Frequent episodes of severe dehydration.

44. Available at surgicalpresentations