Mesenteric Ischemia

[Section Outline]

Description
Etiology

Author:

Rashid F.Kysia

Description

Decreased or occluded blood flow through the mesenteric vessels leading to ischemia or infarction of bowel
Can be from arterial or venous blockage, or low flow states
1 in 1,000 of all ED presentations
1-2% of all admissions for abdominal pain:
- Most cases occur in patients >50 yr
- Mortality as high as 60-70%, particularly if diagnosis/presentation delayed >24 hr

Etiology

Acute mesenteric arterial embolism:
- 50% of cases of acute mesenteric ischemia
- Mean age 70 yr
- Emboli most commonly arise in left atria or ventricle, from a dysrhythmia, valvular lesions, or ventricular thrombus from a prior MI
- Typically lodge 3-10 cm distal to the origin of the superior mesenteric artery (SMA):
  - Preserves blood flow to proximal small and large bowel
- Risk factors include dysrhythmia (especially atrial fibrillation), valvular heart disease, prior MI, aortic aneurysm, or dissection
Mesenteric artery thrombus:
- SMA thrombus in 15% of cases of acute mesenteric ischemia
- Rare in other vessels
- Develops from plaque rupture of mesenteric atherosclerotic disease
- 50-80% may have longstand ing intestinal angina (chronic mesenteric ischemia)
- Risk factors include age, atherosclerotic disease, HTN
Mesenteric venous thrombosis:
- 5-15% of cases of acute mesenteric ischemia
- Subacute/indolent presentation
- 20-40% mortality
- Typically occurs in younger patients with underlying hypercoagulable state
- Risk factors include:
  - Hypercoagulable state (lupus, protein C and S deficiency)
  - Sickle cell disease
  - Antithrombin III deficiency
  - Malignancy (particularly portal)
  - Pregnancy
  - Sepsis
  - Renal failure on dialysis
  - Estrogen therapy
  - Recent trauma or inflammatory conditions
Nonocclusive mesenteric ischemia:
- 20-30% of cases of acute mesenteric ischemia
- Occurs in low cardiac output states with decreased mesenteric blood flow
- Risk factors include CHF, sepsis, hypotension, hypovolemia, diuretic use, recent surgery (especially cardiac), or recent vasopressor requirement
- Poorer survival rates
Chronic mesenteric ischemia:
- “Intestinal angina”:
  - Postprand ial, diffuse abdominal pain occurring ∼1 hr after eating, lasts 1-2 hr
  - Patients may develop food aversions and eat small meals to avoid pain
Uncommon causes:
- Spontaneous mesenteric arterial dissection
- Median arcuate ligament syndrome - compression of the celiac axis or SMA by the arcuate ligament of the diaphragm
- Extrinsic compression from tumors
- Medications:
  - Digitalis
  - Ergotamine
  - Cocaine
  - Pseudoephedrine
  - Vasopressin

Diagnosis ⬆ ⬇

[Section Outline]

Signs and Symptoms
Essential Workup
Diagnostic Tests & Interpretation
Differential Diagnosis

Signs and Symptoms

Sudden-onset, severe, diffuse abdominal pain in acute ischemia:
- Pain out of proportion to exam:
  - Patients may have relatively benign abdominal exam despite severe pain
Nausea
Vomiting
Diarrhea
Occult GI bleeding
Elderly patients can have nonspecific symptoms such as altered mental status, tachypnea, or tachycardia
Late findings:
- Peritoneal signs owing to irreversible bowel ischemia
- Abdominal distention
- Hypoactive bowel sounds

History

Sudden onset of intense pain
Consider risk factors including:
- Hypovolemic/low flow states
- CHF
- Cardiac arrhythmias
- Valvular pathology
- Atherosclerosis
- Abdominal malignancies

Physical Exam

Abdominal pain out of proportion to physical exam during the acute phase of illness

Essential Workup

Maintain a high index of suspicion in patients >50 yr old with unexplained abdominal pain

Diagnostic Tests & Interpretation

Lab

Often nonspecific and nondiagnostic
CBC:
- Elevated WBC count (90% >15,000)
Chemistry panel:
- Approximately 50% have a metabolic acidosis
Amylase:
- Elevated amylase found in 50% of cases
Creatine phosphokinase (CPK) may be elevated
D-dimer:
- Sensitivity as high as 96%, poor specificity
Lactate:
- Elevated in 86% of patients, poor specificity
- Indicative of advanced tissue damage, may not be elevated early in ischemic course
- High levels may correlate with mortality

Imaging

Flat and upright abdominal radiographs:
- Often obtained to rule out acute obstruction or perforation
- Frequently normal
- Late findings:
  - Thumbprinting from bowel wall edema and hemorrhage
  - Pneumatosis intestinalis: Air in bowel wall from tissue necrosis
  - Pneumobilia is a late finding associated with poor outcomes
Abdominal CT scan:
- Can detect bowel wall edema, pneumatosis
- Newer helical and multidetector CT (MDCT) scanners can directly visualize mesenteric vascular anatomy and localize sites of occlusion
- MDCT angiography is more frequently the imaging modality of choice
MRI:
- Excellent images of mesenteric vasculature especially with MR angiography
- Acquisition time and availability limits utility
Angiography:
- Historically the gold stand ard diagnostic modality, now being replaced by MDCT
- Allows for direct visualization of emboli and administration of vasodilating or fibrinolytic agents
- Invasive, time-consuming, and potentially nephrotoxic
Doppler US:
- Can detect decreased blood flow in SMA but more helpful in chronic mesenteric ischemia
- For optimal results the patient should be NPO for 8 hr, limiting the utility of this study in the ED

Differential Diagnosis

Bowel obstruction
Volvulus
GI malignancy
Diverticulitis
Inflammatory bowel disease
Peptic ulcer disease
Perforated viscus
Cholecystitis
Ascending cholangitis
Pancreatitis
Appendicitis
Abdominal aortic aneurysm
MI
Renal stones

Treatment ⬆ ⬇

[Section Outline]

Prehospital
Initial Stabilization/Therapy
ED Treatment/Procedures
Medication

Prehospital

Initiate fluid replacement for dehydrated or hypotensive patients

Initial Stabilization/Therapy

Airway, breathing, and circulation management (ABCs) with fluid resuscitation as needed
Caution:
- Early diagnosis and intervention is critical to decrease mortality

ED Treatment/Procedures

General measures:
- Nasogastric suction to decompress the stomach and bowel
- NPO
- Electrolyte replacement as needed
- Cardiac monitor for dysrhythmia
- Consider invasive cardiac monitoring if patient is unstable
- Monitor urine output
- Analgesics
- Broad-spectrum antibiotics to cover bowel flora (may need to adjust dose if concomitant renal failure):
  - Piperacillin/tazobactam
  - Ampicillin/sulbactam
  - Ticarcillin/clavulanate
  - Alternatives include imipenem, meropenem, 3rd-generation cephalosporins + metronidazole
- Anticoagulation with heparin
- Surgical consultation: All patients with peritoneal signs should have exploratory laparotomy
Specific therapies:
- Papaverine 30-60 mg/h intra-arterial:
  - Phosphodiesterase inhibitor causes mesenteric vasodilatation
  - Administered through angiography catheter
- Intra-arterial thrombolytics can be used in absence of peritonitis or advanced signs of bowel ischemia
- Surgical revascularization often indicated
Caution:
- Avoid vasoconstrictive medications, which may worsen ischemia:
  - If vasopressors are needed, use agents with less impact on mesenteric perfusion - consider dobutamine, low-dose dopamine, milrinone

Medication

Ampicillin/sulbactam: 3 g IV q6h (peds: 100-200 mg/kg/d)
Heparin sulfate: 80 units/kg IV bolus followed by 18 units/kg/hr infusion
Metronidazole: 1 g IV bolus followed by 500 mg IV q6h (peds: 12 mg/kg IV bolus, then 7.5 mg/kg IV q6h)
Piperacillin/tazobactam: 3.375 g IV q6h (peds: 240-400 mg/kg/d)
Ticarcillin/clavulanate: 3.1 g IV q4-6h

Follow-Up ⬆ ⬇

[Section Outline]

Disposition
Follow-up Recommendations

Disposition

Admission Criteria

Admit all patients with mesenteric ischemia

Discharge Criteria

None

Follow-up Recommendations

Surgical consultation

Pearls and Pitfalls ⬆ ⬇

Aggressive pursuit of diagnosis is mand atory
Mortality rises to 80% when the diagnosis is made >24 hr after symptom onset
Early surgical evaluation for emergent operative intervention is mand atory

Additional Reading ⬆ ⬇

CangemiJR, PiccoMF. Intestinal ischemia in the elderly . Gastroenterol Clin North Am. 2009;38(3):527-540.
CudnikMT, DarbhaS, JonesJ, et al. The diagnosis of acute mesenteric ischemia: A systematic review and meta-analysis . Acad Emerg Med. 2013;20(11):1087-1100.
LewissRE, EganDJ, ShrevesA. Vascular abdominal emergencies . Emerg Med Clin North Am. 2011;29(2):253-272.
MartinezJP, HoganGJ. Mesenteric ischemia . Emerg Med Clin North Am. 2004;22(4):909-928.
TekwaniT, SikkaR. High-risk chief complaints III: Abdomen and extremities . Emerg Med Clin North Am. 2009;27(4):747-765.

See Also (Topic, Algorithm, Electronic Media Element)

Abdominal Pain

Codes ⬆

ICD9

557.0 Acute vascular insufficiency of intestine
557.1 Chronic vascular insufficiency of intestine

ICD10

K55.0 Acute vascular disorders of intestine
K55.1 Chronic vascular disorders of intestine

SNOMED

91489000 Acute vascular insufficiency of intestine (disorder)
111354009 Chronic vascular insufficiency of intestine
235843005 Non-occlusive mesenteric ischemia
235842000 Occlusive mesenteric ischemia

section name header

Basics ⬇

Diagnosis ⬆ ⬇

History

Physical Exam

Lab

Imaging

Treatment ⬆ ⬇

Follow-Up ⬆ ⬇

Admission Criteria

Discharge Criteria

Pearls and Pitfalls ⬆ ⬇

Additional Reading ⬆ ⬇

Codes ⬆