View source for Acute arterial ischemia

==Background==
[[File:Arterial System en.png|thumb|Major arteries of the body.]]
*Sudden decrease in perfusion that may result in irreversible limb loss
**Amputation occurs in 10%-15% of patients during hospitalization<ref>Norgren L, Hiatt WR, Dormandy JA, et al. Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASC II). J Vasc Surg. 2007;45 Suppl S:S5-S67. doi:10.1016/j.jvs.2006.12.037</ref>
*Etiology may be thrombotic (80%) or embolic (20%)<ref>Mitchell ME, Carpenter JP. Overview of acute arterial occlusion of the extremities (acute limb ischemia). In: Post TW, ed. UpToDate. Waltham, MA: UpToDate. https://www.uptodate.com/contents/overview-of-acute-arterial-occlusion-of-the-extremities-acute-limb-ischemia?source=search_result&search=Classification%20of%20acute%20extremity%20ischemia&selectedTitle=1~90#H506059593.Last updated: May 30, 2016. Accessed: December 12, 2016.</ref>
**Thrombosis occurs in vessels with existing atherosclerosis 
***Generally have formed collateral circulation
**[[thromboembolism|Embolism]] occurs in vessels usually free of atherosclerosis
***Generally do not have existing collateral circulation
***Results in higher level of limb ischemia than thrombosis

==Clinical Features==
[[File:Arterial thrombosis causing cyanosis.jpg|thumb|Acute embolism to the right femoral artery resulting in ischemia.]]
{{6Ps}}

==Differential Diagnosis==
*[[Peripheral artery disease]]
*[[Vascular injury]]
{{Blue digit DDX}}
{{Foot diagnoses}}

==Evaluation==
{{ABI}}

===Imaging===
[[File:Acuteoccluisionaxartery.png|thumb|Acute occlusion of the axillary artery resulting in an ischemic limb as seen on CT angiography.]]
*Formal angiogram considered gold standard
*CTA as a diagnostic is near the level of formal angiography (96% sensitive, 95% specific)<ref>Jens S, Koelemay MJ, Reekers JA, Bipat S. Diagnostic performance of computed tomography angiography and contrast-enhanced magnetic resonance angiography in patients with critical limb ischaemia and intermittent claudication: systematic review and meta-analysis. Eur Radiol. 2013;23(11):3104-3114. doi:10.1007/s00330-013-2933-8</ref>
*US is sensitive for proximal extremity occlusions, but sensitivity markedly falls off distally and is operator dependent

===Laboratory Evaluation===
*Not useful for diagnosis, but essential for monitoring co-existing conditions and response to anticoagulant therapy. Should include:
**CBC
**BMP
**PT/PTT
**Creatine kinase 

===Thrombosis vs Embolus===
{| {{table}}
| align="center" style="background:#f0f0f0;"|'''Key features'''
| align="center" style="background:#f0f0f0;"|'''Thrombosis'''
| align="center" style="background:#f0f0f0;"|'''Embolus'''
|-
| Source||Usually unknown ||Heart (A-fib most common)
|-
| History||PAD, claudication||Less likely to have PAD and claudication
|-
| Physical exam||Absent pulse. Consistent with PAD: hair loss, thickened nails etc||Absent pulse. Usually no evidence of PAD
|-
| Degree of arthersclerosis||Diffuse ||Minimal 
|-
| Collaterals||Well-developed||Few
|}

===Rutherford Classification<ref>Rutherford RB. Clinical staging of acute limb ischemia as the basis for choice of revascularization method: when and how to intervene. Semin Vasc Surg 2009;22:5-9.</ref>===
{| {{table}}
| align="center" style="background:#f0f0f0;"|'''Category'''
| align="center" style="background:#f0f0f0;"|'''Description/Prognosis'''
| align="center" style="background:#f0f0f0;"|'''Sensory Loss'''
| align="center" style="background:#f0f0f0;"|'''Muscle Weakness'''
| align="center" style="background:#f0f0f0;"|'''Arterial Doppler'''
| align="center" style="background:#f0f0f0;"|'''Venous Doppler'''
|-
| Viable (I)||Not immediately threatened||None||None||Audible||Audible
|-
| Marginally threatened (IIa)||Salvageable if promptly threatened||Minimal (toes) or none||None||Often inaudible||Audible
|-
| Immediately threatened (IIb)||Salvageable with immediate revascularization||Extends beyond toes; pain at rest||Mild to moderate||Usually inaudible||Audible
|-
| Irreversible damage (III)||Major tissue loss or permanent nerve damage inevitable||Profound, anesthetic||Profound, paralysis or rigor||Inaudible ||Inaudible
|}

==Management==
*[[Unfractionated heparin]]
**80 units/kg bolus → 18units/kg/hr gtt
*[[ASA]]
*Dependent positioning
*Pain control
*Vascular surgery consultation (clot retrieval, balloon angioplasty, intraarterial tPA, stenting, bypass)
**Management of embolism = embolectomy (limb salvage decreases after 4-6 hours)
**Management of thrombus = intra-arterial thrombolysis (if non-limb threatening), thrombectomy (if limb-threatening ischmia)
*Interventional radiology if delay in vascular surgery intervention or if unavailable


==Medication Dosing==
{{MedicationDose
| drug = Unfractionated heparin
| dose = 80 units/kg bolus, then 18 units/kg/hr infusion
| route = IV
| context = Anticoagulation to prevent clot propagation
| indication = Acute arterial ischemia
| population = Adult
}}

==Disposition==
===Admission===
*Patients with an ABI of <0.5 warrant admission after immediate consultation with vascular surgery

===Discharge===
*Patients with stable ABI measurements, resolved pain, and chronic occlusive disease can be discharged with vascular surgical follow-up.

==See Also==
*[[Peripheral artery disease]]
*[[Vascular injury]]

==External Links==
*[http://www.emdocs.net/acute-limb-ischemia-pearls-pitfalls/ emDOCS - Acute Limb Ischemia: Pearls and Pitfalls]

==References==
<references/>

[[Category:Surgery]]
[[Category:Vascular]]