ZSFG AM Report Pearls 2/5/18: It’s A Cold-Hearted Limb, Look Into Its Vessels

Thank you to Mia for presenting a really interesting case with lots of twists and possible red herrings. Ultimately, we had the opportunity to talk about acute limb ischemia which was causing a gap metabolic acidosis, which was at least partially explained by a lactic acidosis from isolated poor perfusion to the limb rather than systemic hypoperfusion.

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Acute Limb Ischemia

Diagnosis:

Physical Exam Findings – the 6 P’s

  • Parasthesia
  • Pain
  • Pallor
  • Pulselessness
  • Poikilothermia
  • Paralysis

Differential Diagnosis for ACUTE Limb Ischemia (i.e. what can cause an acute loss of blood supply)

  • Acute thrombosis (either native vasculature or of a graft)
  • Embolism from heart or other diseased artery (esp in Afib, acute MI, HFrEF, prosthetic valves)
  • Dissection
  • Trauma
  • Compartment syndrome
  • Phlegmasia cerulea dolens (DVT causing severe leg swelling)
  • Vasopressors

Differential Diagnosis for CRITICAL Limb Ischemia (different from ACUTE limb ischemia in that duration of ischemia has been >2 weeks or longer)

  • Severe atherosclerosis (PAD)
  • Thromboangiitis obliterans
  • Vasculitides
  • Vasospasm

Stages of Limb Ischemia

Management (when suspect acute thrombosis):

  • Heparin gtt to prevent propagation of clot (everyone)
  • Endovascular Revascularization 
    • NOT GOOD if cannot tolerate ongoing ischemia for 12-24hrs, nonviable limb, suspected infected bypass graft
      • Catheter-directed thrombolytic administration
        • Success in restoring blood flow reported in 75-92% of cases
        • Can add GPIIb/IIIa receptor antagonists but has not been shown to improve outcomes (although may accelerate reperfusion and reduce distal embolization)
      • Mechanical Devices (i.e. aspiration, mechanical fragmentation, ultrasound-assisted fibrinolysis)
        • Data from trials comparing these devices with pharmacological thrombolysis are lacking
  • Open Surgical Revascularization (directed by etiology and often combo therapy)
    • Thromboembolectomy with balloon catheter
    • Bypass Srugery
    • Adjuncts (endarterectomy, patch angioplasty, intraoperative thrombolysis)
  • Endovascular vs. Open Surgical Revascularization
    • See the reference article for additional details, BUT in summary
    • If viable, marginally threatened limb, recent occlusion (no more than 2 weeks duration), thrombosis of a synthetic graft, occluded stent, and one identifiable distal runoff vessel, THEN catheter-directed thrombolysis has best results
    • If immediately threatened limb or symptoms of occlusion for more than 2 weeks, THEN surgical vascularization

Ischemic Limb Algo

Musical Inspiration: https://youtu.be/o7aShcmEksw

Source: Creager MA, Kaufman JA, & Conte MS. (2012). Acute limb ischemia. NEJM. 366:2198-2206.

Evernote: Acute Limb Ischemia: https://www.evernote.com/shard/s509/sh/ed656a1e-c1c1-4202-806c-259a9372f19b/2b9918d4a28696049cb4a13ef70a0c18

 

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