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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
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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
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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
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describe the vascular supply of the bowel. what are "watershed areas"?
(see Khuen ppt)
Watershed areas = splenic flexure & rectosigmoid jct
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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
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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
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what is the pathogenesis of mesenteric ischemia?
- Acute:
- ebmolism from Lside of heart to SMA-->middle colic (75%)
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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)
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what are potential complications of ischemic bowel?
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wha is the management of ischemic bowel?
surgery, type & area depends on extent of necrosis
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*Don't forget physio, histo, anatomy, pharm, & micro!
:)
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what are the clinical manifestations of (viral) gastroenteritis?
- acute onset vomitting AND/or diarrhea
- fever/N/abd cramps, anorexia, malaise
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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
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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
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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
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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).
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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.
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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!!!
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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
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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
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