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Mesenteric Ischemia, Emergency Medicine

Basics

Description

- 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

- 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

- 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

- 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

- 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

  • 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 ischemiaMean age 70 yrEmboli most commonly arise in left atria or ventricle, from a dysrhythmia, valvular lesions, or ventricular thrombus from a prior MITypically lodge 3 " ô10 cm distal to the origin of the superior mesenteric artery (SMA):Preserves blood flow to proximal small and large bowelRisk 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 ischemiaRare in other vesselsDevelops from plaque rupture of mesenteric atherosclerotic disease50 " 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 ischemiaSubacute/indolent presentation20 " ô40% mortalityTypically occurs in younger patients with underlying hypercoagulable stateRisk factors include:Hypercoagulable state (lupus, protein C and S deficiency)Sickle cell diseaseAntithrombin III deficiencyMalignancy (particularly portal)PregnancySepsisRenal failure on dialysisEstrogen therapyRecent trauma or inflammatory conditions
  • Nonocclusive mesenteric ischemia:20 " ô30% of cases of acute mesenteric ischemiaOccurs in low cardiac output states with decreased mesenteric blood flowRisk 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 hrPatients may develop food aversions and eat small meals to avoid pain.
  • Uncommon causes:Spontaneous mesenteric arterial dissectionMedian arcuate ligament syndrome " öcompression of the celiac axis or SMA by the arcuate ligament of the diaphragmExtrinsic compression from tumorsMedications:DigitalisErgotamineCocainePseudoephedrineVasopressin

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 ischemiaAbdominal distentionHypoactive 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 patientsIndicative 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 perforationFrequently normalLate findings:Thumbprinting from bowel wall edema and hemorrhagePneumatosis intestinalis: Air in bowel wall from tissue necrosisPneumobilia is a late finding associated with poor outcomes
  • Abdominal CT scan:Can detect bowel wall edema, pneumatosisNewer helical and multidetector CT (MDCT) scanners can directly visualize mesenteric vascular anatomy and localize sites of occlusionMDCT angiography is more frequently the imaging modality of choice
  • MRI:Excellent images of mesenteric vasculature especially with MR angiographyAcquisition time and availability limits utility
  • Angiography:Historically the gold standard diagnostic modality, now being replaced by MDCTAllows for direct visualization of emboli and administration of vasodilating or fibrinolytic agentsInvasive, time-consuming, and potentially nephrotoxic
  • Doppler US:Can detect decreased blood flow in SMA but more helpful in chronic mesenteric ischemiaFor 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 bowelNPOElectrolyte replacement as neededCardiac monitor for dysrhythmiaConsider invasive cardiac monitoring if patient is unstableMonitor urine outputAnalgesicsBroad-spectrum antibiotics to cover bowel flora (may need to adjust dose if concomitant renal failure):Piperacillin/tazobactamAmpicillin/sulbactamTicarcillin/clavulanateAlternatives include imipenem, meropenem, 3rd-generation cephalosporins + metronidazoleAnticoagulation with heparinSurgical 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 catheterIntra-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