EM@3AM – Acute Limb Ischemia

Author: Erica Simon, DO, MHA (@E_M_Simon, EM Chief Resident, SAUSHEC, USAF) // Edited by: Alex Koyfman, MD (@EMHighAK, EM Attending Physician, UTSW / Parkland Memorial Hospital) and Brit Long, MD (@long_brit, EM Attending Physician, SAUSHEC, USAF)

Welcome to EM@3AM, an emdocs series designed to foster your working knowledge by providing an expedited review of clinical basics. We’ll keep it short, while you keep that EM brain sharp.

A 62-year-old male with a history of paroxysmal a.fib (CHADS2: 0; daily ASA¹) presents for evaluation of left lower extremity (LLE) numbness and weakness. The patient reports the onset of his symptoms five hours prior to arrival, during his granddaughter’s dance recital. He denies slurred speech, visual changes, facial and upper extremity sensory and motor deficit. He denies right lower extremity symptoms.  HPI is negative for back pain, recent trauma, joint pain, and joint redness prior to symptom onset. ROS is unremarkable. Surgical history is significant only for remote inguinal hernia repair.

 Triage VS: T99.7°F Oral, HR 82, BP 129/76, RR 24, SpO2 98% on room air

Physical exam:

Neuro: LLE: weakness of plantarflexion and dorsiflexion; decreased sensation L4-S2 dermatomes below the knee

Cardiac: irregularly irregular

Vascular: Cool, mottled LLE; femoral pulse palpable, popliteal pulse non-palpable, dorsalis pedis and posterior tibial pulses non-palpable. Doppler confirms the absence of popliteal, dorsalis pedis, and posterior tibial pulses.

EKG: NSR, 82 bmp, axis WNL, no ST-T wave changes, QT WNL

What is the patient’s diagnosis? What’s the next step in your evaluation and treatment?

Answer: Acute Limb Ischemia^1-4

• Risk Factors: Conditions that pre-dispose to thrombosis (hypercoagulable state, arterial aneurysms, peripheral arterial disease (atherosclerotic plaque rupture), etc.) or embolism (atrial fibrillation, post MI, left ventricular dysfunction, mechanical cardiac valve with sub therapeutic anticoagulation, etc.).
  • Trauma is an uncommon etiology: limb ischemia may occur secondary to direct vessel injury and subsequent thrombosis.²

• Clinical Presentation: Classically taught as the six Ps: pain, paresthesia, pallor, poikilothermia, pulselessness, and paralysis. Patients may also report claudication.
  • Considered to be acute in onset if symptoms began within 2 weeks of presentation ²

• Evaluation:
  • Assess limb: appearance, temperature, pulses (including by Doppler), sensation, and strength
  • Lower extremities: ABI < 0.3 = subcritical acute ischemia²
• Treatment:
  • Consult vascular surgery:
    • The Society for Vascular Surgery publishes classification standards based upon clinical and Doppler findings (limb viable vs. threatened vs. irreversibly damaged) which direct management and treatment.⁴
  • Discuss initiation of heparin bolus 80 U/kg, then 18 U/kg/hr + ASA PO.²

• Pearls:
  • Palpable pulses in the contralateral extremity suggests embolism as the underlying etiology.³
  • Morbidity and mortality rates are high in patients with acute limb ischemia: 10-15% undergo limb amputation during hospitalization.²

References:

1. Hart R, Pearce L, Rothbart R, McAnulty J, Asinger R, et al. Stroke with intermittent atrial fibrillation: incidence and predictors during aspirin therapy. Stroke prevention in atrial fibrillation investigators. J Am Coll Cardiol. 35(1):183-187.
2. Creager M, Kaufman H, Conte M. Clinical Practice. Acute limb ischemia. N Engl J Med. 2012; 366(23):2198-2206.
3. Earnshaw J. Acute Ischemia: Evaluation and Decision Making. In: Rutherford’s Vascular Surgery. 8th ed. Philadelphia: Saunders Elsevier, 2014: 2518-2527.e1.
4. Rutherford D, Baker J, Ernst C, Johnston K, Porter J, et al. Recommended standards for reports dealing with lower extremity ischemia: revised version. J Vasc Surg. 1997; 26(3): 517-538.