Basics
Description
- Decreased or occluded blood flow through the mesenteric vessels leading to ischemic or infarcted bowel
- Can be from arterial or venous blockage, or low flow states.
- 1 in 1,000 of all hospital admissions
- 1 " ô2% of all admissions for abdominal pain:
- Most cases occur in patients >50 yr.
- Mortality as high as 60 " ô70%, 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 " ô10 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 " ô80% may have longstanding intestinal angina (chronic mesenteric ischemia).
- Risk factors include age, atherosclerotic disease, HTN.
- Mesenteric venous thrombosis:
- 5 " ô15% of cases of acute mesenteric ischemia
- Subacute/indolent presentation
- 20 " ô40% 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 " ô30% 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 " Ł:
- Postprandial, diffuse abdominal pain occurring ó ł ╝1 hr after eating, lasts 1 " ô2 hr
- Patients may develop food aversions and eat small meals to avoid pain.
- Uncommon causes:
- Spontaneous mesenteric arterial dissection
- Median arcuate ligament syndrome " öcompression of the celiac axis or SMA by the arcuate ligament of the diaphragm
- Extrinsic compression from tumors
- Medications:
- Digitalis
- Ergotamine
- Cocaine
- Pseudoephedrine
- Vasopressin
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
Rapidity of onset of pain é á
Physical Exam
Abdominal pain out of proportion to physical exam during the acute phase of illness é á
Essential Workup
Maintain a high index of suspicion in patients >50 yr old with unexplained abdominal pain. é á
Diagnosis 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.
- Lactate:
- Elevated in 90% of patients
- Indicative of advanced tissue damage, may not be elevated early in ischemic course.
- High levels 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 standard 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
Pre-Hospital
Initiate fluid replacement for dehydrated or hypotensive patients. é á
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 " ô60 mg/h intra-arterial:
- Phosphodiesterase inhibitor causes mesenteric vasodilatation.
- Administered through angiography catheter
- Intra-arterial thrombolytics can be used.
- Surgical revascularization often indicated
- Caution:
- Avoid vasoconstrictive medications, which may worsen ischemia:
- If vasopressors are needed, use agents with less impact on mesenteric perfusion " öconsider dobutamine, low-dose dopamine, milrinone.
Medication
- Ampicillin/sulbactam: 3 g IV q6h (peds: 100 " ô200 mg/kg/d)
- Heparin sulfate: 80 U/kg IV bolus followed by 18 U/kg/h 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 " ô400 mg/kg/d)
- Ticarcillin/clavulanate: 3.1 g IV q4 " ô6h
Follow-Up
Disposition
Admission Criteria
Admit all patients with mesenteric ischemia. é á
Discharge Criteria
None é á
Followup Recommendations
Surgical consultation é á
Pearls and Pitfalls
- Aggressive pursuit of diagnosis is mandatory.
- Mortality rises to 80% when the diagnosis is made >24 hr after symptom onset.
- Early surgical evaluation for emergent operative intervention is mandatory.
Additional Reading
- Cangemi é áJR, Picco é áMF. Intestinal ischemia in the elderly. Gastroenterol Clin North Am. 2009;38:527 " ô540.
- Krupski é áWC, Selzman é áCH, Whitehill é áTA. Unusual causes of mesenteric ischemia. Surg Clin North Am. 1997;77(2):471 " ô499.
- Lewiss é áRE, Egan é áDJ, Shreves é áA. Vascular abdominal emergencies. Emerg Med Clin North Am. 2011;29(2):253 " ô272.
- Martinez é áJP, Hogan é áGJ. Mesenteric ischemia. Emerg Med Clin North Am. 2004;22:909 " ô928.
- McKinsey é áJF, Gewertz é áBL. Acute mesenteric ischemia. Surg Clinic North Am. 1997;77(2):307 " ô318.
- Tekwani é áT, Sikka é áR. High-risk chief complaints III: Abdomen and extremities. Emerg Med Clin North Am. 2009;27(4):747 " ô765.
See Also (Topic, Algorithm, Electronic Media Element)
Abdominal Pain é á
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