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!