What questions should be asked to a patient with a history of vascular disease, diabetes, or recent trauma, presenting with lower extremity discoloration, to determine the underlying cause and appropriate management?

Clinical Assessment of Lower Extremity Discoloration

When a patient presents with lower extremity discoloration, immediately assess for critical limb-threatening ischemia by asking about rest pain, non-healing wounds, and tissue loss, while simultaneously evaluating for infection—even in the absence of pain—as peripheral neuropathy can mask typical presentations in high-risk patients. 1, 2

Essential History Questions

Vascular Symptom Characterization

• Pain pattern and timing: Ask specifically if pain occurs with walking a predictable distance and resolves within 10 minutes of rest (typical claudication), or if pain is present at rest, particularly at night requiring leg dependency for relief (critical limb ischemia) 1
• Pain quality and location: Document whether discoloration is accompanied by aching, burning, cramping, or fatigue in the buttock, thigh, calf, or ankle 1
• Wound history: Inquire about any non-healing or slow-healing wounds, ulcerations, or history of trivial trauma (e.g., aggressive nail clipping) that preceded the discoloration 1
• Functional capacity: Determine actual walking ability before assuming the patient is "asymptomatic"—many elderly patients with multiple comorbidities cannot walk enough to reveal claudication symptoms ("masked LEAD") 1

Critical Risk Factor Documentation

• Age and atherosclerotic risk factors: Document if patient is ≥65 years, or ≥50 years with diabetes, smoking history, dyslipidemia, hypertension, or chronic kidney disease 1, 3
• Diabetes-specific history: Ask about duration of diabetes, glycemic control (HbA1c), presence of neuropathy, and foot care practices, as diabetes increases PAD risk 2-4 fold and amputation risk 7-15 fold 1, 4
• Smoking exposure: Quantify pack-years and current status, as smoking increases PAD risk 2-6 fold and is present in >80% of PAD patients 1
• Polyvascular disease: Ask about history of coronary artery disease, stroke, carotid disease, or renal artery stenosis, as one-third to two-thirds of PAD patients have concomitant coronary disease 1

Physical Examination Priorities

Vascular Assessment

• Pulse palpation: Systematically palpate and grade (0=absent, 1=diminished, 2=normal, 3=bounding) bilateral femoral, popliteal, dorsalis pedis, and posterior tibial pulses 1
• Skin inspection with shoes and socks removed: Evaluate for color changes (pallor with elevation, dependent rubor), temperature asymmetry, hair loss, trophic skin changes, hypertrophic nails, and integrity of intertriginous areas 1
• Ischemia-specific signs: Check for elevation pallor with extended capillary refill time (>2 seconds after finger pressure) and dependent rubor 1
• Ulcer characteristics: If present, document location, size, appearance (arterial ulcers are typically painful unless neuropathy is present), and signs of infection or gangrene 1

Neuropathy and Infection Screening

• Neuropathy assessment: Test for reduced pain sensitivity, as diabetic neuropathy can mask both ischemic pain and infection symptoms 1, 2
• Infection signs: Maintain extremely high suspicion for infection even without typical pain, warmth, or erythema, as PAD plus infection increases amputation risk nearly 3-fold 2

Immediate Diagnostic Testing

• Ankle-brachial index (ABI): Measure immediately in all patients with discoloration and risk factors or abnormal pulse examination; ABI <0.90 confirms PAD, <0.6 indicates critical limb ischemia requiring urgent vascular evaluation 1, 2
• Alternative testing for medial calcinosis: If ABI >1.40 (noncompressible vessels common in diabetes/CKD), obtain toe-brachial index, toe pressures, or transcutaneous oxygen pressure (TcPO2) 1, 2

Critical Clinical Pitfalls to Avoid

• Never apply compression therapy without first checking ABI, as this can precipitate gangrene in patients with PAD 2
• Never attribute bilateral discoloration to "just venous stasis" without ruling out PAD and infection through objective testing 2
• Do not assume absence of pain means absence of critical ischemia in elderly or diabetic patients with neuropathy—look for objective signs of tissue loss 1, 2
• Recognize "masked LEAD": Elderly patients with multiple comorbidities may present with sudden severe ischemia (e.g., toe necrosis after minor trauma) despite being labeled "asymptomatic" because they cannot walk far enough to develop claudication 1