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Short Bowel Syndrome
(SBS)
Dr.Atul Kumar Mishra
M.S. (Gen.Surgery)
SBS
Result of surgical resection, congenital defect, or disease-associated loss of absorption
Characterized by inability to maintain protein-energy, fluid, electrolyte, or micronutrient balance when on a normal diet
Definition Presence of <one-third (approximately200
cm) of remaining small intestine
Clinically defined by malabsorption, diarrhea, steatorrhea, fluid and electrolyte disturbances and malnutrition
Functional or anatomic loss of extensive segments of small intestine that result in loss of absorptive surface area and increase in intestinal transit
EPIDEMIOLOGY True incidence of SBS in United States unknown
Overall neonatal incidence 24.5 per 100,000 livebirth, with higher incidence in premature infants (Wales et al)
15% of adult who undergo intestinal resection suffer from SBS, 3/4th from massive resection, 1/4th from multiple sequential resections
Case fatality rate 37.5%
With emergence of intestinal rehablitation centers and advancement in surgical procedures 70% patient alive 1year
Survival rates for pediatric SBS 52% - 95% at 5 years
SBS can be classified into 3 anatomic subtypes
Intestinal Anatomy
TYPE 1 – End jejunostomy
TYPE 2 – Jejunocolic anastomosis
TYPE 3 – Jejunoileocolic anastomosis
Causes of Short Bowel SyndromeAdults :
Postoperative Irradiation Cancer Mesentric vascular
disease Crohn disease Trauma Desmoid tumours
Childrens : Gastroschisis Necrotizing enterocolitis
Midgut volvulus Intestinal atresia
Shackelford’s Surgery of the Alimentary Tract 7th edition
Pathophysiologic Consequences of Massive
Resection GENERAL Malnutrition and weight loss Diarrhea and steatorrhea Vitamin and mineral
deficiencies Fluid and electrolyte
abnormalities
SPECIFIC Gastric hypersecretion Cholelithiasis Liver disease Nephrolithiasis
Pathophysiology
Manifestation related to site of resection
Duodenal resection Jejunal resection Ileal resection Loss of ileocecal valve Colon
Duodenal resection
Protein , CHO, fat maldigestion Ca, mg, iron, folate malabsorption Fat soluble vit deficiency
If significant portion or all of jejunum is resected, absorption of proteins, carbohydrates, most vitamins and minerals can be unaffected because of adaptation in ileum.
BUT unfortunately, enzymatic digestion suffers because of irreplaceable loss of enteric hormones produced by jejunum.
ALSO, gastrin levels rise, causing gastric hypersecretion. High acid output from stomach injure SI mucosa.
JEJUNUM
In addition, TI is site of absorption of bile salts and vitamin B-12
Continued loss of bile salts leads to fat malabsorption, steatorrhea, and loss of fat-soluble vitamins
Ileal resection severely decreases the capacity to absorb water and electrolytes.
ILEUM
Peptide YY, released from L cells in distal ileum and colon, slows gastric emptying and intestinal transit. In event of distal ileal and colonic resection, this feedback inhibition is lost
Retention of ileocecal valve plays pivotal role in massive small bowel resection
If ileocecal valve is lost, transit time is faster, and loss of fluid and nutrients is greater
Colonic bacteria can colonize the small bowel, worsening diarrhea and nutrient loss
ILEOCECAL VALVE
Preservation of the colon has positive and negative attributes.
Increasing colonic water absorption as much as 5 times its normal capacity
Resident bacteria capacity to metabolize undigested CHO into SCFA These are a preferred fuel source for coloncytes & body
Increasing the incidence of urinary calcium oxalate stone formation
Small intestinal bacterial overgrowth
COLON
NEGATIVE
POSITIVE
Phases Of SBS
Acute Phase Immediately after bowel resection and lasts for 1-3 months Ostomy output greater than 5 liters per day Life threatning dehydration and electrolyte imbalances Extremely poor absorption of all nutrients Development of hypergastrenemia and hyperbilirubinemia
Adaptation phase
Begins 12 – 24 hours after resection and last up to 1-2 years
90% adaptation occurs during this phase Enterocyte, villus hyperplasia and increased crypt depth
ocurrs resulting in increased absorptive area Luminal nutrition is essential for adaptation and should
be initiated as early as possible Parenteral nutrition is essential through out this period
Maintenance phase
Absorptive capacity is maximum during this phase Nutritional metabolic homeostasis can be achieved
with oral feeding
Change in morphorogy
Macroscopic Elongation and dilation
Microscopic Villus: increase height and diameter Crypt: elongation Epithelial cell life cycle: increase proliferation Decrease apoptosis
Change in functional capacity
Increase absorption per unit length Upregulation of sodium glucose
transporter
Factors Influencing Intestinal Adoptation GASTROINTESTINAL REGULATORY PEPTIDES Luminal contents Nutrients Secretions
SYSTEMIC FACTORS Growth factors Hormones Cytokines
TISSUE FACTORS Immune system Mesenchymal factors Mesentric blood flow Neural influences
Lab investigation
Blood U&E, bone profile, & mg, PRN then
biweekly CBC, triglycerides, cholesterol Weekly Folate, vit B12, copper, zinc, Monthly Blood gas and AG for suspected lactic
acidosis.
Microbiology
If sepsis suspected; blood & urine c/s Cultures from both the central and
peripheral sites. Consider opportunistic infections, so
search for fungal infection.
Imaging Studies
To assess for potential complications, Infection
Abdominal ultrasonography to look for fungal balls in the kidney
Bowel obstruction Plain radiography. Barium imaging of the bowel
Liver disease Abdominal US to study the liver, biliary tract,
& presence of ascites.
Clinical Features History of several intestinal resections as in Crohn
disease or major vascular event like midgut volvulus or embulus to superior mesenteric vessel
Diarrhea is almost constant finding (with or without steatorrhea)
Significant weight loss, lethargy and fatigue Dehydration, protein calorie malnutrition, and loss of
critical vitamins and minerals
Physical examination
Significant protein and calorie malnutrition present with temporal wasting, loss of digital muscle mass and edema. Skin dry and flaky
In children poor growth occurs Signs of vitamin and mineral deficiency appear
Management
The goals of nutritional therapy1.Maintain adequate nutrition2.Promote intestinal adaptation3.Avoid complications
Management
1. Fluid and electrolyte balance
2. Nutrition
Require TPN at least initially
Enteral feeding gradually introduced once ileus has resolved
3. Macro and micronutrients
4. Drugs: PPI, Antimotilty agents
HOME PN
Unfortunately, some patients are extremely difficult/impossible to wean from parenteral nutritionand and maintained on “home PN or HPN”
HOME PN
Common characteristics of these patients: Very short remaining small bowel segments (<60 cm) Loss of colon Loss of ileocecal valve or Small bowel strictures with stasis and bacterial overgrowth
Managements for SBS Nutritional support Fluid & electrolyte replacement Medication for possible complications Trophic therapy Randomized, controlled trials have not shown
glutamine and/or growth hormone to improve intestinal absorption
PARENTERAL NUTRITION
Typically, patients who have undergone massive enterectomy require TPN, once hemodynamic stability has been achieved, for the first 7 to 10 days after surgery
25 to 30 kcal/kg per day based on ideal body weight for adults
Indications for continued parental nutrition Poor weight gain or loss of maintenance
weight Extensive stomal fluid and electrolyte
losses which cannot be replaced orally
TPN Dextrose is providing 3.4 kcal/mL. Maximum
dextrose infusion rate should be 5 to 7 mg/kg/min Blood glucose should be monitored at least daily,
optimally QID, and should be <180 to 200 mg/dL, Addition of regular insulin toTPN may be required. If insulin is required, it should be added toTPN bag with initial dose of 0.1 U/g dextrose
Intravenous lipids used to provide 20 to 30 percent of infused calories
Protein supplied in form of amino acids and should be supplied at 1.0 to 1.5 gm/kg/day
Dietary Treatment When fluid and electrolyte balance has stabilized, bowel sounds have returned, and there
is < 2L/day of diarrhea, elemental diet may be initiated Goal is to provide patients with approximately 25 to 30 kcal/kg/day and 1.0 to 1.5 g/kg per
day of protein
Micronutrients, including water-soluble vitamins(B1, B2, B3, B6, B12, biotin, folate, C) and fat-soluble vitamins (A, D, E, K), and trace elements (Zn, Se) often require supplementation
Water-soluble vitamin deficiency is rare
Diet and Fluid SuggestionCOLON PRESENT COLON ABSENT
Carbohydrate 50%-60% of caloric intakeComplex carbohydrate
40%-50%
Fat 20%-30% caloric intake 30%-40%
Ensure adequate essential fats MCT/LCT
LCT
Protein 20%-30% caloric intakeHigh biologic values
same
Fiber Soluble soluble
Fluids ORS and/or hypotonic ORS
Oxalate Restrict _______
Lipid Medium-chain triglycerides
Better absorbed in presence of bile acid or pancreatic insufficiency
Long-chain triglycerides : more effective in stimulating intestinal adaptation
Mix MCT + LCT
Oral rehydration solutions (ORS)
To decrease dehydration and to decrease TPN fluid requirements in patients with residual jejunum ending in a jejunostomy
WHO: formulated by dissolving following in 1 L tap water:
NaCl (2.5 g), KCl (1.5 g), Na2CO2 (2.5 g), and glucose (table sugar, 20 g)
Optimal Na concentration : at least 90 mmol/L, which is usual
concentration of small bowel effluent NTHU: Babyate oral electrolyte maintenance sol.
ORS
With residual colon in continuity, ORS may of value, but, provided sufficient Na present in diet, amount of Na in ORS may not be as critical since colon readily absorbs Na and water against a steep electrochemical gradient
For patients with no jejunum, but have residual ileum, presence of glucose in ORS is not critical because ileal water absorption is not affected by presence of glucose
Patients with SBS should be cautioned against consumption of plain
water and should be encouraged to drink ORS whenever they are thirsty
Factors affecting TPN dependenceIn addition to residual small bowel length other
factors are: Presence of colon because it can absorb
large amount of fluid and electrolytes and absorption of short chain fatty acids
Intact ileocecal valve, it delays transit of chyme from small intestine to colon Increasing the time of contact of nutrient with absorptive small bowel mucosa
Contd
. Healthy small bowel has more absorptive
capacity than diseased small bowel Resection of jejunum is better tolerated than
ileum because ileum is associated with bile salt and vitamin B12 absorption
Factors that influence length of time until independent of TPN
Extent/ location of resection Presence or absence of colon Presence /Absence of ICV Degree of adaptation in remaining bowel Extent of residual bowel disease or
complications e.g. adhesions, strictures
Contd Anatomically TPN dependence persists when
100 cm of residual small bowl without functioning colon
And 60cm with functioning colon Among infants weaning from TPN has been
achieved even with 10cm of residual small gut
Pharmacologic therapy
Decrease stomal secretory losses H2 blockers, PPI & octreotide ??Loperamide
Ursodeoxycholic acid: Improves bile acid–dependent bile flow
Antibiotics used to prevent small-bowel overgrowth Insufficient data regarding -glutamine GH some benefit
Complications of SBS
Diarrhea Cholerheic diarrhea / Steatorrhea Gastric Hypersecretion Nephrolithiasis D-Lactic acidosis
Diarrhea
Anti-motility agents, such as loperamide hydrochloride
Octreotide (100 mcg SC, tid, 30 minutes before meals) Used only if fluid intravenous requirements are >3 L daily (High output jejunostomy)
Octreotide useful to slow intestinal transit and increase water and sodium absorption
Octreotide may impair post resectional intestinal adaptation. There is also an increased risk for cholelithiasis in a patient group already predisposed to this problem
Steatorrhea
Luminal digestion of lipid may be impaired because of impaired bile salt reabsorption related to resected ileum (>100 cm)
Insufficient evidence to recommend use of bile acid supplements to decrease steatorrhea; and they may worsen diarrhea
Cholestyramine is not useful in patients with >100
cm of ileal resection, and it may actually worsen steatorrhea because of the binding of bile salts
Gastric hypersecretion
Massive small bowel resection is associated with hypergastrinemia during initial first 6 months after surgery
High-dose H2 antagonists and proton pump inhibitors reduce gastric fluid secretion, and fluid losses during first 6 months post-enterectomy
Renal stones Normally, oxalate in diet binds to dietary calcium and is excreted
in stool In presence of significant fat malabsorption, dietary calcium
preferentially binds to free fatty acids, rendering the oxalate free to pass into colon
Once absorbed into colon, oxalate renally filtered, where it binds to calcium, resulting in hyperoxaluria and calcium oxalate nephrocalcinosis and nephrolithiasis
In patients with colon in continuity, oxalate should be restricted in diet
Oral Ca supplements may be for prevention of Ca-oxalate nephrolithiasis
Bacterial overgrowth
Resection of ileocecal valve may allow colonic bacteria to populate the small intestine, resulting bacterial overgrowth
Bacteria compete for nutrients with the enterocytes Treatment with antibiotics
D-lactic acidosis
diagnosis : serum level of D-lactic acid is >3 mmol/L
Standard treatment consists of minimizing oral carbohydrates, correction of metabolic acidosis, and long-term suppression of pathogenic floras with antibiotics
SICU protocol for SBS
Outcome prediction: <100 cm small bowel TPN
>100 cm small bowel,<100 cm small bowel + colon,100~150 cm small bowel + partial colon Partial TPN
>100 cm small bowel + colon TPN generally not required
Phamacological bowel compensationFor enhancing bowel adaptation Growth hormone at 0.03-0.13 s/c for
4weeks Parenteral or enteral Glutamine
Surgery for SBS• AUTOLOGOUS INTESTINAL RECONSTRUCTION SURGERY (AIRS)
Improve Intestinal Function and Motility/Maximize Remnant1.Avoid resection2.Restore continuity3.Recruit bypassed intestinal segments4.Relieve obstruction due to adhesions and strictures5.Slow intestinal transit6.Taper dilated bowel segments
Increase Absorptive Area1.Intestinal lengthing procedures2.Longitudinal intestinal lengthening and tailoring (LILT/Bianchi)3.STEP4.Isolated bowel segment (Kimura/IOWA procedure)
• INTESTINAL TRANSPLANTATION
Nontransplantation procedures To improve surface area or to slow transit
time Bianchi procedure (intestinal tapering or
lengthening) Indicated in small bowel with bacterial
overgrowth, dilated bowel and continued malabsorption
Cutting bowel longitudinally, and create a segment of bowel twice length, half diameter without loss of mucosal surface area
Contd
Goal of these operations is to slow intestinal transit time and increasing intestinal length
Operations for slow transit time include: Segmental reversal of small bowel Interposition segment
of colon between segments of small intestine Construction of small intestinal valves
Bowl Lengthening procedures
Longitudinal intestinal lengthening and tailoring procedure especially in pediatric patients with dilated small bowel
Tapering/Tapering/PlicationPlication
Bowel lengtheningBowel lengthening
Serial Transverse Enteroplasty (STEP)
SURGERY can both lengthen and taper the small intestine in some patients
During procedure, a short segment of intestine is carefully cut and reshaped into a longer, thinner segment. Longer, thinner intestine is thought to function more efficiently and lead to better absorption of food
Indications Impending or overt liver failure IV access loss Frequent central line related sepsis Intestinal failure
Small bowel transplantation
Intestinal Transplantation
Combined intestine-liver transplantation
Isolated intestinal transplantation
Is only alternative for patients who have developed end-stage liver disease related to SBS or long-term TPN therapy
Considered for patients with significant liver disease that has not yet progressed to cirrhosis
Also, for those with significant fluid losses and who have episodes of frequent, severe dehydration despite appropriate medical management.
Prognosis
Ultimately patient with SBS may be successfully wean from TPN although entire process may take several years
Intestinal transplantation should be consider as a last resort
Conclusion Early management of SBS replacement of fluid
and electrolytes
Enteral feeding should begin once patient stabilizes
Continuous enteral feeding preferred
Several pharmacological approaches have been tested to enhance intestinal adaptation and improve feeding tolerance. None are proven helpful, but studies are ongoing
THANKS FOR YOUR ATTENTION!
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