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Ischemic bowel disease Flashcards

1
Q

If pt presents with any belly pain esp older pt what should always be on your DDx?

A
  • mesenteric ischemia
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2
Q

Incidence of ischemic bowel disease? Mortality rate? Patterns/

A
  • incidence increases with age
  • dx frequently is delayed, high mortality: 50-90%
  • patterns:
    small and/or large bowel
    diffuse or localized
    segmental or focal
    superficial or transmural
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3
Q

What are the 4 major causes of acute mesenteric ischemia?

A
  • SMA emobolism (50%)
  • SMA thrombosis (15-25%): often superimposed on pts with progressive atherosclerotic disease, also occurs with trauma or infection
  • nonocclusive ischemia: 20-30%
  • mesenteric venous thrombosis: 5%
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4
Q

Occlusive causes of acute mesenteric ischemia?

A

arterial: usually SMA
- embolic: Afib, valves
- thrombotic: atherosclerosis, trauma, infection

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5
Q

Nonocclusive cuases of acute mesenteric ischemia?

A

hypoperfusion (low cardiac output or shock (MI, arrythmias, septic shock) - leading to splanchnic vasoconstriction

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6
Q

Circulation to the intestines?

A
  • primarily SMA and IMA
  • lots of collateral circulation
  • reqrs 10-35% of CO
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7
Q

Regulation of intestinal circulation?

A
  • perfusion pressure
  • neura and hormonal mechanisms
  • sympathetic nervous system, renin angiotensin system, vasopressin from the pituitary:
    vasopressin - causes mesenteric (arterial) vasoconstriction and venous dilation
    reduces portal venous pressure in pts bleeding from portal HTN
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8
Q

hallmarks of clinical presentation of ischemic bowel?

A
  • severe cramping abdominal pain, out of proportion to physical findings, poorly localized
  • worst pain of their life, may hear some bruits (if they have atherosclerotic disease)
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9
Q

clinical presentation of ischemic bowel?

A
  • abdominal exam may be normal initially
  • occult blood in stool
  • as bowel ischemia worsens:
    abdominal distension, absent bowel sounds, peritoneal signs, +/- feculant odor to the breath
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10
Q

Clincial syndromes of ischemic bowel (occlusive and non-occlusive)?

A

occlusive:

  • mesenteric arterial embolism
  • mesenteric arterial thrombosis
  • mesenteric venous thrombosis

non-occlusive:
hypoperfusion

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11
Q

RFs assoc with acute mesenteric arterial embolism?

A
  • advanced age
  • coronary artery disease
  • cardiac valvular disease
  • hx of dysrhythmias - esp Afib
  • post- MI mural thrombi
  • hx of thromboembolic disease
  • aortic surgery
  • aortography
  • coronary angiography
  • aortic dissection
  • CHF (low output)
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12
Q

Main characteristics of mesenteric arterial embolism: who it effects? What is usually effected?

A
  • median age: 70, 2/3 women (smaller vessels)
  • SMA often involved and affects the jejunum
  • 6-8 cm beyond arterial origin, near middle colic artery
  • thrombus form L atrium, L ventricle or cardiac valves: over 20% of cases have mult emboli, arteriolar vasoconstriction also occurs
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13
Q

Clinical presentation of mesenteric arterial embolism?

A
  • sudden onset of severe pain, that is out of proportion to physical findings 75%
  • N/V, frequent BMs
  • occult blood in stool 25%
  • more favorable prognosis than SMA thrombosis
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14
Q

mesenteric arterial thrombosis - usual culprits?

A
  • atherosclerotic disease
  • trauma
  • infection
  • does not appear to be assoc with coagulopathy
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15
Q

Characteristics of mesenteric arterial thrombosis?

A
  • usually can elicit a hx of chronic mesenteric ischemia
  • usual site of blockage is orign of SMA or celiac axis
  • less favorable prognosis compared with embolic
  • sxs don’t develop until sig blockage (collateral circulation) which can complicate revascularization
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16
Q

What pop more commonly affected by mesenteric venous thrombosis? What tpye of clots are the most common? Onset?

A
  • younger pop: 48-60
  • primary 20%
  • secondary clot 80%
  • onset can be acute or develop over the course of a few weeks
  • thrombosis of superior mesenteric vein or intestinal strangulation from hernia or volvulus: 30% of cases involve thrombosis of the portal vein
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17
Q

sxs in mesenteric venous thrombosis?

A

more insidious onset of sxs:

  • pain diffuse and nonspecific initially, but later becomes constant
  • anorexia 53-54%
  • vomiting 41-77%
  • diarrhea 36%, constipation 13-34%
  • hematemesis 9-425
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18
Q

RFs for mesenteric venous thrombosis?

A
  • **hypercoagulable state (upt to 75% have hypercoag. disorder)
  • **portal HTN
  • abdominal infections
  • blunt abdominal trauma
  • pancreatitis
  • splenectomy
  • malignancy in portal region
  • personal or family hx of DVT or PE
  • dehydration
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19
Q

PP of intestinal ischemia in mesenteric venous thrombosis?

A
  • decreased mesenteric venous blood flow
  • results in bowel wall edema (how you can tell the diff b/t arterial and venous on CT)
  • fluid efflux into bowel lumen
  • results in systemic hypotension and increase in blood viscosity
  • this results in diminished arterial flow
  • leading to submucosal hemorrhage and bowel infarction
20
Q

Cause of nonocclusive mesenteric ischemia? RF?

A
  • result of splanchnic hypo perfusion and vasoconstriction
  • RF: atherosclerotic disease
  • often pt has a life-threatening illness/is being tx (ex: CHF, MI, sepsis)
  • pathogenesis: mesenteric vasospasm - homeostatic mechanism maintains cardiac and cerebral blood flow, vasopressin and angiotensin involved
21
Q

Mortality of nonocclusive mesenteric ischemia? Sxs?

A
  • high mortality (up to 70%)
  • severity and location of pain may be different than occlusive mesenteric ischemia:
    going to have progressive abdominal pain, bloating, N/V, mental status changes
  • up to 25% of pts don’t have abdominal pain
  • listen for bowel sounds!!
22
Q

Ischemia in the colon presentation?

A
  • 90% of pts over age of 60
  • acute precipitating cause is rare
  • pts don’t appear severely ill
  • mild abdominal pain, tenderness present
  • rectal bleeding, bloody diarrhea typical
  • colonoscopy is procedure of choice
23
Q

Main cause of arterial emboli?

A
  • afib, MI
24
Q

Main cause of arterial thrombosis?

A
  • atherosclerotic disease
25
Q

Main cause of venous thrombosis?

A
  • underlying disorder in coagulation (hypercoagulable), neoplasm
26
Q

Main cause of nonocclusive mesenteric ischemia?

A
  • nonocclusive mesenteric ischemia: low flow states
27
Q

Work up of ischemic bowel disease?

A
  • lab

- imaging: plain abdominal xrays, CT scan of abdomen

28
Q

What will you see on labs in ischemic bowel disease?

A
  • increase in WBCs with predominance of immature cells
  • increased HCT (hemoconcentration)
  • increase in amylase (50%), increase phosphate (80%)
  • increase in serum lactate
    77-100% sensitivity/42% specificity
  • metabolic acidosis: any pt with abdominal pain and metabolic acidosis has intestinal ischemia until proven otherwise
29
Q

What will you see on plain x-rays?

A
  • pneumatosis intestinalis
  • portal venous gas
  • thickened bowel wall with thumb-printing
  • air fluid levels
  • dilated bowel loops (can look like a bowel obstruction)
  • gasless abdomen
30
Q

In cases of surgiclly proven acute mesenteric ischemia - this is what is seen?

A
  • air fluid levels (67%)
  • dilated bowel loops (18%)
  • gasless abdomen (10%)
  • pneumatosis (2%)
  • portal venous gas (2%)
31
Q

What is pneumatosis intestinalis?

A
  • gas cysts in bowel wall
  • it isn’t gas in the bowel lumen
  • suggestive of necrotizing enterocolitis
32
Q

What is portal venous gas?

A
  • accum of gas in portal vein and its branches

- a variety of causes such as ischemic bowel, intra-abdominal sepsis and other

33
Q

Imaging for dx ischemic bowel disease - steps?

A
  • upright and supine plain abdominal x-rays are the first step in eval of acute abdomen
  • free air, obstruction, ileus, intusseception, volvulus
  • mesenteric ischemia is diff to dx on plain films alone
  • CT is next step if dx isn’t made on plain fims and if pt is stable
34
Q

Preferred imaging? How will appearance vary?

A
  • CT
  • oral and IV contrast, do IV first
  • oral necessary for eval of mucosal thickening of bowel wall
  • if just ordering CTA may not want oral contrast b/c it can obscure view of mesenteric vessels
- appearance will vary based on:
cause
severity
localization
extent and distribution
Presence and degree of submucosal or intramural hemorrhage, superimposed bowel wall infection, or bowel wall perf
35
Q

Findings on CT?

A
  • bowel wall thickening: most common finding in ischemic colitis, colonic infarction, and venous occlusion
  • bowel dilation (can be assoc with wall thinning)
  • fat stranding and ascites
  • varying degrees of attenuation: high attenuation (white), low (black)
  • pneumatosis and portomesenteric gas
36
Q

When is a CTA or MRA indicated?

A
  • CTA: good study for eval of suspected intestinal ischemia but don’t do if planning on percutaneous angiography too (excessie contrast with 2 studies)
  • MRA: better at dx venous occlusions
37
Q

When is a mesenteric percutaneous arteriography used? When can you not use this?

A
  • if dx is in doubt after non-invasive radiologic eval
  • if dx is fairly certain and need consideration for percutaneous tx or for surgical planning
  • can’t be used for venous occlusions
38
Q

Dx and Tx process of ischemic bowel disease?

A
  • hemodynamic monitoring and support: correct hypotension, hypovolemia
  • correction of metabolic acidosis
  • broad spectrum abx
  • NG tube for gastric decompression
  • vasopressors that have less effect on mesenteric perfusion: dobutamine, low dose dopamine, milrinone
  • anticoag unless actively bleeding
  • correction of arrhythmias
  • then imaging
  • may start with plain films or CT but if strong clinical suspicion should go directly to angiography
  • at angiography can give papaverine (potent vasodilator) directly to relieve mesenteric vasoconstriction
  • if peritoneal signs, may proceed directly to the OR for surgical repair
39
Q

What is the gold std dx study for acute arterial ischemia?

A
  • mesenteric angiography
40
Q

Tx for MAE?

A
  • surgery and embolectomy or local infusion of thrombolytic therapy
41
Q

Tx for MAT?

A
  • surgery with thrombectomy + revascularization or heparinization
42
Q

Tx for MVT?

A
  • heparinization + resection of infarcted bowel
43
Q

Tx for nonocclusive mesenteric ischemia?

A
  • papaverine infusion during angiography
  • reverse underlying conditions
  • repeat angiography can be done in 24 hrs
  • surgical exploration reserved for pts with peritoneal signs

tx goal: reverse underlying cause

44
Q

Basic care guidelines for these ischemic bowel pts?

A
  • cardiac monitor, venous access, O2
  • may reqr fluid resuscitation
  • broad spectrum abx
  • surgery
45
Q

Characteristics of chronic mesenteric ischemia?

A
  • intestinal angina
  • episodic or constant intestinal hypoperfusion
  • secondary to atherosclerosis
  • strongly assoc with meals
  • pts generally have sxs for a year, have unintentional wt loss, hurts to eat
    tx: stents to open up blocked areas

GI (21 decks)

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