Acute Limb Ischemia

Author: Michelle Lin, MD
Updated: 8/13/2010

Acute Limb Ischemia

  • True vascular emergency
  • Golden Window = 6 hours
  • Etiologies:

Most common: Thromboembolic cause

Less common causes:

  • Vascular dissection
  • Compartment syndrome
  • Thoracic outlet syndrome
  • Trauma
  • Vasospasm
  • Vasculitis
  • Low intravascular volume

Focused physical exam checklist

  • Cardiac: Check for murmur, atrial fibrillation
  • Extremity: Check for signs of chronic peripheral vascular disease: hair loss, foot ulcer, decreased pulse, muscle atrophy
  • Neurological: Check for sensory and motor loss

  • Vascular: Grade peripheral pulses

    • 0 = No Doppler signal
    • 1 = Reduced
    • 2 = Normal
    • 3 = Increased
    • 4 = Bounding

  • Rutherford Classification scheme for ALI (Rutherford et al)

    • Thrombotic occlusions usually class I or IIA because of presence of collateral vasculature
    • Embolic occlusions usually class IIB or III

Class I

  • Category: viable, no limb threat
  • Prognosis: none
  • Sensory Loss: none
  • Muscle Weakness: none
  • Arterial Doppler Signal: audible
  • Venous Doppler Signal: audible

Class IIA

  • Category: threatened, marginal
  • Prognosis: salvageable if treated properly
  • Sensory Loss: minimal or none
  • Muscle Weakness: none
  • Arterial Doppler Signal: +/- audible
  • Venous Doppler Signal: audible

Class IIB

  • Category: threatened, immediate
  • Prognosis: salvageable if treated immediately
  • Sensory Loss: more than just toes
  • Muscle Weakness: mild to moderate
  • Arterial Doppler Signal: rarely audible
  • Venous Doppler Signal: audible

Class III

  • Category: irreversible limb loss or permanent damage
  • Prognosis: limb loss or permanent damage
  • Sensory Loss: profound
  • Muscle Weakness: profound
  • Arterial Doppler Signal: none
  • Venous Doppler Signal: none

Workup

  • Ankle brachial index (ABI)
  • Electrocardiogram
  • CBC
  • Type and screen
  • Basic metabolic panel
  • PT/PTT
  • Creatine kinase
  • Troponin

Imaging

  • First line imaging = Digital subtraction angiography (DSA)
  • Ultrasound, CT angiography, MR angiography – not well studied in ALI and loss of time-to-intervention
  • No imaging if unstable patient --> go straight to amputation

ED treatment

  • Aspirin
  • Unfractionated heparin (consider no bolus and lower infusion due to risk of hemorrhage)
  • Position extremity in dependent position
  • Avoid extremes of temperature
  • Pain control

Management Plan

Interventional radiology = Catheter-directed (intra-arterial) thrombolysis +/-mechanical thrombectomy

  • If Class I or IIA ischemia; duration <14 days, esp if bypass graft; high operative risk

Operating room = Open thrombectomy, bypass

  • If Class IIB or III ischemia; symptoms > 14 days

Amputation = If class III and high risk for reperfusion injury

References

  • Rutherford RB, Baker JD, Ernst C, Johnston KW, Porter JM, Ahn S, Jones DN. Recommended standards for reports dealing with lower extremity ischemia: revised version.J Vasc Surg. 1997 Sep;26(3):517-38. [PubMed]