Rosen & Barkin's 5-Minute Emergency Medicine Consult (14 page)

5. Wait 30–45 sec

6. Intubate when optimal conditions achieved

*Consider pretreatment with fentanyl (1–2 μg/kg) IV push (over 1–2 min) and lidocaine
(1.5 mg/kg) IV push if concern for increased intracranial pressure or severe hypertension

*Consider defasciculating dose of paralytic if concern for increased intracranial pressure (see table for dosage)

*Atropine: 0.02 mg/kg IV push (for children <1 y)

BASICS

• Focal dilation of the aortic wall with an increase in diameter by at least 50% (>3 cm).
  
• 95% are infrarenal.
  
• Rapid expansion or rupture causes symptoms.
  
• Rupture can occur into the intraperitoneal or retroperitoneal spaces
  
• Intraperitoneal rupture is usually immediately fatal
  
• Average growth rate of 0.2–0.5 cm/yr
  
• Of ruptures:
  
  • 90% overall mortality
    
  • 80% mortality for patients who reach the hospital
    
  • 50% mortality for patients who undergo emergency repair
    

• Risk increases with advanced age.
  
• Present in:
  
  • 4–8% of all patients older than 65 yr
    
  • 5–10% of men 65–79 yr old
    
  • 12.5% of men 75–84 yr old
    
  • 5.2% of women 75–84 yr old
    

• Risk factors:
  
  • Male gender
    
  • Age >65 yr
    
  • Family history
    
  • Cigarette smoking
    
  • Atherosclerosis
    
  • HTN
    
  • Diabetes mellitus
    
  • Connective tissue disorders:
    
    • Ehlers–Danlos syndrome
      
    • Marfan syndrome
      
• Uncommon causes:
  
  • Blunt abdominal trauma
    
  • Congenital aneurysm
    
  • Infections of the aorta
    
  • Mycotic aneurysm secondary to endocarditis
    
• Rupture risk factors:
  
  • Size (annual rupture rates):
    
    • Aneurysms 5–5.9 cm = 4%
      
    • Aneurysms 6–6.9 cm = 7%
      
    • Aneurysms 6.9–7 cm = 20%
      
  • Expansion:
    
    • A small aneurysm that grows >0.5 cm in 6 mo is at high risk for rupture.
      
  • Gender:
    
    • For aneurysms 4.0–5.5 cm, women have 4× higher risk of rupture compared to men with similar sized aneurysms.
      

DIAGNOSIS

• Abdominal, back, or flank pain:
  
  • Vague, dull quality
    
  • Constant, throbbing, or colicky
    
  • Acute, severe, constant
    
  • Radiates to chest, thigh, inguinal area, or scrotum
    
  • Flank pain radiating to the groin in 10% of cases
    
• Lower extremity pain
  
• Syncope, near-syncope
  
• Unruptured are most often asymptomatic
  

• Unruptured:
  
  • Abdominal mass or fullness
    
  • Palpable, nontender, pulsatile mass
    
  • Intact femoral pulses
    
• Ruptured:
  
  • Classic triad (only 1/3 of the cases):
    
    • Pain
      
    • Hypotension
      
    • Pulsatile abdominal mass
      
  • Systemic:
    
    • Hypotension
      
    • Tachycardia
      
    • Evidence of systemic embolization
      
  • Abdomen:
    
    • Pulsatile, tender abdominal mass
      
    • Flank ecchymosis (Grey Turner sign) indicates retroperitoneal bleed.
      
    • Only 75% of aneurysms >5 cm are palpable.
      
    • Abdominal tenderness
      
    • Abdominal bruit
      
    • GI bleeding
      
  • Extremities:
    
    • Diminished or asymmetric pulses in the lower extremities
      
• Complications:
  
  • Large emboli: Acute painful lower extremity
    
  • Microemboli: Cool, painful, cyanotic toes (“blue toe syndrome”)
    
  • Aneurysmal thrombosis: Acutely ischemic lower extremity
    
  • Aortoenteric fistula: GI bleeding
    

• Unstable patients:
  
  • Bedside abdominal US
    
  • Explorative surgery without further ancillary studies
    
• Stable, symptomatic patients:
  
  • Abdominal CT
    

• Type and cross-match blood
  
• CBC
  
• Creatinine
  
• Urinalysis
  
• Coagulation studies
  

• Plain radiographs:
  
  • Abdominal or lateral lumbar radiographs
    
  • Only if other tests are unavailable
    
  • Curvilinear calcification of the aortic wall or a paravertebral soft-tissue mass indicates abdominal aortic aneurysm (AAA) in 75% of patients.
    
  • Cannot identify rupture
    
  • Negative study does not rule out AAA.
    
• Abdominal ultrasound:
  
  • 100% sensitive and 92–99% specific for detecting AAA prior to rupture
    
  • In emergent setting, useful to determine presence of AAA.
    
  • Ultrasound findings consistent with AAA are enlarged aorta >3 cm or focal dilatation of the aorta.
    
  • Sensitivity has been reported as low as 10% following rupture.
    
  • Indicated in the unstable patient
    
• Abdominal CT scan:
  
  • Contrast is not necessary to make the diagnosis but CT angiogram is required for surgical planning for an endovascular approach
    
  • Will demonstrate both aneurysm and site of rupture (intraperitoneal vs. retroperitoneal)
    
  • Allows more accurate measurement of aortic diameter
    

• Other abdominal arterial aneurysms (i.e., iliac or renal)
  
• Aortic dissection
  
• Renal colic
  
• Biliary colic
  
• Musculoskeletal back pain
  
• Pancreatitis
  
• Cholecystitis
  
• Appendicitis
  
• Bowel obstruction
  
• Perforated viscus
  
• Mesenteric ischemia
  
• Diverticulitis
  
• GI hemorrhage
  
• Aortic thromboembolism
  
• Myocardial infarction
  
• Addisonian crisis
  
• Sepsis
  
• Spinal cord compression