GI_FINAL_Session 8

  1. What are the clinical manifestations of acute ischemic bowel? What are some Sx's of chronic intestinal ischemia? What about non-occlusive forms?
    • abrupt in onset, w/varying degrees of severity
    • LLQ pain & tenderness
    • abd cramping, possibly N/V
    • mild diarrhea, often bloody
    • *non-occlusive = diffuse, waxing/waning pain
    • chronic inestinal ischemia:
    • abd cramping & pain following the ingestion of a meal
    • wgt loss & chronic diarrhea
    • **abd pain w/o wgt loss is NOT chronic
  2. what is mesenteric ischemia? compare acute and chronic.
    • mesenteric ischemia = reduction in instestinal blood supply
    • acute:
    • most often involves SMA
    • from emboli, thrombi or vasoconstriction 2ndary to low flow
    • Chronic:
    • post prandial abd pain, marked wgt loss
    • caused by repeated transient episodes of inadequate intestinal blood flow
  3. what is colonic ischemia?
    • is the most frequent form of mesenteric ischemia
    • mostly involves the L colon
    • mostly elderly
    • Etiology:
    • low-flow state
    • embolus
    • post MI
    • post AAA reconstruction
    • closed loop construction (lift side intact ileocecal valce)
    • volvulus
    • mesenteric V Thrombosis
  4. describe the vascular supply of the bowel. what are "watershed areas"?
    (see Khuen ppt)

    Watershed areas = splenic flexure & rectosigmoid jct
  5. compare acute colonic ischemia with acute ichemia of the small bowel
    • acute Colonic:
    • >60yo
    • acute precipitating cause is rare
    • pt's don't appear very ill
    • mild abd pain, tenderness
    • rectal bleeding/bloody diarrhea
    • **colonoscopy = procedure of choice!

    • acute ischemia of small bowel:
    • age varies w/etiology
    • acute trauma/cause is usual
    • pt's look very ill
    • pain is severe, mostly w/o tenderness
    • bleeding uncommon until very late
    • **angiography is best 1st procedure
  6. what diagnostic tests are indicated for mesenteric ischemia? ischemic colitis?
    • Mesenteric Ischemia:
    • routine labs (CBC, serum chem, coag profile, art bg, amylase, lipase, lactic acid, blood type & cross match & cardiac enzymes).
    • regardless of the need for urgent surgery, emergent admission to a bed or IVU is recommended for resuscitation & further evaluation
    • useful tests that should not delay surgery are: ECG, XRay, CT, & Mesenteric angiography
    • for suspicion of ACUTE arterial occlusion is laparotomy is the "gold standard"
    • *from lecture: do CT first (air bubbles = pneumotosis intestinalis), then maybe do angiogram
    • for ischemic colitis specifically:
    • colonoscopy should be performed to assess integrity of colon mucosa
  7. what is the pathogenesis of mesenteric ischemia?
    • Acute:
    • ebmolism from Lside of heart to SMA-->middle colic (75%)
  8. name the regions that are at risk for decreased blood flow.
    • Griffith's point (collateral vessels @ splenic flex)
    • Sudeck's point (coll. vess. @ desc/sigmoid colon)
  9. what are potential complications of ischemic bowel?
    • perforation
    • sepsis
  10. wha is the management of ischemic bowel?
    surgery, type & area depends on extent of necrosis
  11. *Don't forget physio, histo, anatomy, pharm, & micro!
  12. what are the clinical manifestations of (viral) gastroenteritis?
    • acute onset vomitting AND/or diarrhea
    • fever/N/abd cramps, anorexia, malaise
  13. describe the virology of the norovirus.
    • Family of Caliciviridae
    • prototype = Norwalk Virus
    • +ssRNA, non-enveloped Icosahedral
    • Shellfish concentrate the virus, but can get with fecal-oral contamination too
    • it is somewhat resistant to Cl- so can be transmitted in swimming pools
    • *use immuno assays for detecting antiviral ab's
  14. describe the virology of Rotavirus.
    • Family = Reoviridae
    • dsRNA, naked, icosadedral
    • D/V/fever
    • virus destroys epithelial cells
    • infection travels seasonally (southwest in autumn, northeast by early summer)
    • vaccine available; immunological protection occurs after infection
  15. In someone who presents with 2d of watery diarrhea, vomitting, & fever, and h/o eating shellfish 2d before onset of Sx's, what is the ddx of etiology?
    • dx: gastroenteritis
    • etiology:
    • Norovirus
    • Vibrio cholerae & V. parahaemolyticus
    • these can be found in shellfish
  16. describe the virology of V. cholerae & V. parahaemolyticus.
    • G-, facultative anaerobic curved rod, Oxidase +
    • some produce Cholera toxin
    • --> AB toxin (B binds ganglioside GM1 on intestinal epithelial cells; A interacts w/G proteins that stim cAMP overproduction = hypersecretion of fluids/electrolytes)
    • found in marine waters
    • **need relatively high inoculums (~105-108) compared to C. jejuni (medium); Shigella AND Norovirus & Rotovirus (low).
  17. what are diagnostic tests for suspected gastroenteritis?
    • For viral etiology, it is a dx of exclusion; often you only Tx dehydration (check skin turgor & electrolytes) and replenish with pedialyte
    • For bacterial etiology check stool & blood for leukocytes; culture stool if indicated.
  18. what is the management protocol for gastroenteritis?
    • For self limiting types, hydration w/pedialite
    • tell them to AVOID dairy (anything with lactose) to avoid further complicating the illness
    • can prescribe Loperamide to decrease diarrhea
    • NO ABX!!!
  19. What is the ddx for travele's diarrhea?
    • Infectious causes:
    • ETEC
    • EAEC
    • Salmonela
    • Shigella
    • Campylobacter

    • Non-infectious:
    • excess sorbitol
    • heavy metal poisoning
    • carcinoid tumors
    • VIPomas
    • thyrotoxicosis
    • AI
    • Parathyroid insufficiency
    • lactase deficiency
    • pancreatic or biliary insufficiency
    • celiac spru
  20. what are the clinical presentations that would suggest traveler's diarrhea?
    • h/x of travel to developing or different countries
    • develops w/in 2-10d of traveling
    • many loose stools/d
Card Set
GI_FINAL_Session 8
Westernu GI final, session 8