Emergency Medicine Hub / Cardiovascular Emergencies • 3 min read • 3 sections

Peripheral Arterial Disease & Chronic Limb-Threatening Ischemia

Comprehensive emergency evaluation and protocolized management of peripheral arterial disease (PAD) and chronic limb-threatening ischemia (CLTI): atherosclerotic stenosis of lower extremity arteries, distinguishing intermittent claudication from ischemic rest pain, Fontaine and Rutherford staging systems, bedside Ankle-Brachial Index (ABI) technique and false normal non-compressible calcified vessels, dry vs. wet gangrene, differentiating acute arterial embolism ('6 Ps') from acute-on-chronic in situ thrombosis, wound care, and emergent vascular revascularization indications.

Resuscitation Quick Actions • First 2 Minutes

High-Acuity

CLTI Definition

Ischemic rest pain (forefoot pain relieved by dangling foot over bed) OR ischemic ulcers/gangrene persisting > 2 weeks

Severe ABI Cutoff

ABI <= 0.40 indicates severe peripheral ischemia and high risk of limb loss; normal ABI is 0.91 to 1.30

Non-Compressible ABI Trap

ABI > 1.40 indicates calcified, non-compressible arteries in diabetics/ESRD; measure Toe-Brachial Index (TBI <= 0.70 confirms PAD)

Wet vs Dry Gangrene

Dry gangrene: sterile mummification (dry sterile dressing, urgent outpatient revascularization); Wet gangrene: INFECTED, CREPITANT (STAT SURGICAL I&D + IV PIP-TAZO)

Heparin for Acute Thrombosis

If sudden deterioration in rest pain or sensory loss occurs: bolus Unfractionated Heparin 80 units/kg IV immediately

Dependent Rubor

Buerger's test: pallor on limb elevation, followed by intense, dusky cyanotic erythema upon placing leg in dependent position

Bottom-Line Clinical Pearl

Chronic Limb-Threatening Ischemia (CLTI/critical limb ischemia) is defined as PAD presenting with ischemic rest pain (burning pain in the forefoot/toes aggravated by elevation and relieved by dependency) or ischemic tissue loss (non-healing ischemic ulcers or gangrene) persisting > 2 weeks. The Ankle-Brachial Index (ABI) is diagnostic: normal is 0.91–1.30; moderate PAD is 0.41–0.90; severe ischemia is <= 0.40. In diabetic or renal failure patients, medial calcinosis renders vessels non-compressible (falsely elevated ABI > 1.40); use Toe-Brachial Index (TBI < 0.70 is diagnostic). If acute-on-chronic thrombosis occurs, initiate IV Unfractionated Heparin immediately and obtain emergent CT Angiography of the aorta with lower extremity runoff to guide limb-salvage bypass or endovascular revascularization.

1. Clinical Classification: Fontaine & Rutherford Staging

Peripheral arterial disease (PAD) is characterized by atherosclerotic obstruction of the infrarenal aorta, iliac, femoropopliteal, and infrapopliteal tibial arteries, progressively compromising distal nutrient blood flow to muscles and cutaneous tissues.

Fontaine Stage	Rutherford Category	Clinical Presentation & Functional Status	Amputation Risk & Prognosis
Stage I	Category 0	Asymptomatic; detectable only by reduced Ankle-Brachial Index (ABI)	Extremely low limb loss risk; optimize medical therapy (statin, aspirin).
Stage IIa/IIb	Category 1, 2, 3	Intermittent Claudication (mild, moderate, or severe): cramping muscle ache (calf, thigh, buttock) reproducible with exercise, relieved by rest	Amputation risk $< 1\%$ per year; supervised exercise therapy and cilostazol.
Stage III	Category 4	Ischemic Rest Pain: severe, burning pain in the forefoot and toes, worse when recumbent in bed, relieved by hanging the leg dependent over the bed	High risk of limb loss. Defines Chronic Limb-Threatening Ischemia (CLTI); mandates urgent vascular revascularization.
Stage IV	Category 5 & 6	Ischemic Tissue Loss: minor non-healing ischemic ulceration (Category 5) or major gangrene extending above metatarsal level (Category 6)	Extreme risk of limb loss (> 25% at 1 year) without immediate revascularization; evaluate for superimposed deep tissue infection.

2. Bedside Ankle-Brachial Index (ABI) Technique & TBI

Measure systolic blood pressure in both arms (brachial artery) and both ankles (dorsalis pedis and posterior tibial arteries) using a handheld Doppler probe and pneumatic blood pressure cuff. Calculate the ABI for each leg: divide the higher systolic pressure of the dorsalis pedis or posterior tibial artery in that leg by the higher systolic pressure between the two arms.

ABI Value	Interpretation	Clinical Management Protocol
$0.91\text{ to }1.30$	Normal Arterial Perfusion	Normal resting perfusion; if claudication symptoms persist, consider exercise ABI.
$0.71\text{ to }0.90$	Mild PAD	Lifestyle modification, statin therapy, antiplatelet agent, risk factor control.
$0.41\text{ to }0.70$	Moderate PAD	Supervised walking program, cilostazol; routine vascular surgery referral.
$\le 0.40$	Severe Ischemia/CLTI	Critical Limb Ischemia: high risk of spontaneous necrosis. Order urgent CT Angiogram and immediate Vascular Surgery consult.
$> 1.30\text{ to }1.40$	Non-Compressible/Medial Calcinosis	Calcified Mönckeberg's arteriosclerosis (common in diabetes and ESRD). The cuff cannot compress the stiff vessel, yielding falsely high numbers. Must order a Toe-Brachial Index (TBI): a $TBI \le 0.70$ confirms true severe PAD.

3. Wet vs. Dry Gangrene: The Emergency Sepsis Distinction

Gangrene Variant	Pathology & Clinical Features	Emergency Resuscitative Actions
Dry Gangrene	Coagulative ischemic necrosis without bacterial infection: tissue is shriveled, hard, dry, black, and demarcated from viable skin; no crepitus; patient non-toxic	Keep clean and dry (dry sterile gauze); do NOT debride or paint with wet soaks; urgent vascular surgery consult for outpatient or inpatient elective bypass.
Wet Gangrene	Liquefactive ischemic necrosis with superimposed polymicrobial bacterial infection: tissue is boggy, weeping foul-smelling purulent fluid, blistering, with surrounding ascending cellulitis, lymphangitis, subcutaneous crepitus, and systemic sepsis	Surgical Emergency: Stat broad-spectrum IV antibiotics (Vancomycin 15–20 mg/kg IV + Piperacillin-Tazobactam 4.5g IV); aggressive fluid resuscitation; emergent surgical debridement or guillotine amputation to prevent fatal septic shock.

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