Acute arterial ischemia
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Background
- Sudden decrease in perfusion that may result in irreversible limb loss.
Etiology
- Thrombotic vs Embolic
- Thrombosis occurs in vessels with existing atherosclerosis that have already formed existing collaterals.
- Embolism occurs in vessels usually free of atherosclerosis, therefore without existing collaterals. This results in higher level of limb ischemia.
Clinical Features
6 Ps
- Pain - Claudication or pain with leg elevation; typically earliest sign
- Paraesthesia - May be associated with weakness; preservation of light touch is good guide to viability
- Pallor
- Paralysis
- Pulselessness - May be accompanied by skin changes; late finding
- Poikilothermia - Limb is cool to touch when compared to other side; late finding
Differential Diagnosis
Foot diagnoses
Acute
- Foot and toe fractures
- Subtalar dislocation
- Metatarsophalangeal joint sprain (turf toe)
- Acute arterial ischemia
- Calcaneal bursitis
Subacute/Chronic
- Diabetic foot infection
- Peripheral artery disease
- Plantar fasciitis
- Trench foot
- Ingrown toenail
- Paronychia
- Tinea pedis
- Morton's neuroma
- Diabetic neuropathy
Evaluation
ABI
- Measuring
- Position patient supine
- Measure SBP from both brachial arteries using cuff and handheld Doppler over the AC fossa
- Measure SBP from both DP and PT arteries using cuff placed just proximal to the malleoli with Doppler over artery (5-8% of normal patients have absent DP pulse)
- Calculate ABI on each leg by taking the highest ankle SBP divided by the highest brachial SBP and record to 2 decimal places
- Using calculation
- 0.91–1.30: normal
- 0.70–0.90: mild occlusion
- 0.40–0.69: moderate occlusion
- <0.40: severe occlusion
- >1.30: poorly compressible/calcified vessels
Imaging
- Angiogram considered gold standard
- CTA
- US
Thrombosis vs Embolus
Key features | Thrombosis | 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 |
Management
- Unfractionated heparin
- 80 units/kg bolus; then infuse 18units/kg/hr
- ASA
- Dependent positioning
- Pain control
- Fluid resuscitation and treatment of heart failure as needed to improve limb perfusion
- 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:
- Non-limb threatening: intra-arterial thrombolytic
- Severe limb-threatening ischemia: thrombectomy plus bypass grafting
- Management of embolism:
Disposition
- Acute limb ischemia requires inpatient management