Diagnosis and Treatment of Acute Mesenteric Ischemia

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Diagnosis and Treatment of Acute Mesenteric
Ischemia
Eric S. Weiss, M.D.
Department of Surgery The Johns Hopkins Medical
Institutions Baltimore, MD
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Case Presentation

• 81 F presents in the early evening to the
  emergency department with a vague abdominal pain
  and no additional complaints
• Pain is described as diffuse located primaily in
  the lower abdomen
• PMH includes
• CAD s/p angioplasty with stents
• Diverticulosis
• CT scan ordered but never completed in ED

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Case Presentation

• At approximately midnight she is transferred to
  the floor without a diagnosis
• At 2am the on call resident called
• Hypotension
• Shortness of breath
• Worsening abdominal pain
• ABG 7.15/24/84/8
• Transferred to MICU for vasopressor and
  respiratory support

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Case Presentation

• General surgery consulted
• ABG 7.05/35/100/8 on 100 positive pressure
  ventilation
• Lactate 12
• Dopamine and Norepinephrine infusing
• Decision made to take to the operating room for
  an exploratory laparotomy
• Bowel found to be grossly necrotic form ligament
  of treitz to descending colon.

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Acute Mesenteric Ischemia

• Severe disease affecting 1/100,000 hospitalized
  patients
• Diagnosis often delayed
• Mortality rates high
• 60 80

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Classification

• Acute Mesenteric Ischemia (AMI)
• Chronic Mesenteric Ischemia (CMI)
• Intestinal Angina
• Colonic Ischemia (CI)

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Classification
Acute Mesenteric Ischemia (AMI)
Occlusive Disease
Non Occlusive Disease
Arterial Occlusion
Low Flow States
Venous Occlusion
Vasopressor Use
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Pathophysiology

• Bowel is very good at living with low flow
• 25 of capillaries remain open during fasting
• With thrombosis, or emboli
• intestinal blood flow falls below 30ml/100
• lt70 mmHg SBP
• ischemia develops

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Pathophysiology

• Impaired microcirculation leads to activation of
  inflamatory cells and cytokine release, and
  bacterial translocation
• SIRS and DIC result, leading to further bowel
  necrosis

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Presentation

• Severe abdominal pain of abrupt onset
• Poorly localized
• Classically out of proportion to physical exam
• Bowel evacuation with heme positive stools (50)

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Risk Factors

• Age (gt 65)
• Generally affects older individuals
• Highest mortality among those gt80
• Atherosclerotic disease
• Arrythmias
• Cardiogenic shock with pressor dependence
• Known hypercoaguable state
• Intrabdominal Malignancy

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Diagnostic Tests

• No reliable test
• Helpful adjuncts include
• ABG acidosis indicates ischemia but only
  develops in 50
• Lactic acid
• Amylase
• Creatine phosphokinase
• D-Dimer (100 sensitivity in one study with 38
  specificity)
• Leukocytosis greater than 15K supports
  diagnosis

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Radiography

• Plain Radiograph
• Can show thickening or pneumatosis intestinalis
• Generally useful only for excluding other causes
  of acute abdomen
• Ultrasound
• Highly user dependent
• MRI
• too long to be helpful in acute setting

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Radiography

• Computed Tomography
• Bowel wall thickening
• Occlusion with contrast
• Pneumatosis
• Portal venous air
• Non sensitive (26 sensitivity)
• Angiography
• Gold standard
• Allows for diagnosis and treatment

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Managment

• Use of preoperative angiography is still
  controversial
• With peritoneal signs exploratory laparotomy
  mandated
• Embolectomy
• Resection of dead bowel
• Laser dopler, dopler US and fluoresceine dye are
  usefull adjuncts to assess viability
• Routine second look laparotomy is recommended

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Summary A Practical Approach
Non Vascular Cause
Stable
Angiography
Clinical, radiographic and laboratory data
suggestive of AMI
Vascular Cause
Laparotomy
Unstable
2nd look later
Severe disease with high mortality and whose
diagsosis relies on clinical information