What is the management approach for an elderly patient with Diabetes Mellitus (DM) and Hypertension (HTN) presenting with nocturnal burning pain in the right foot that improves with dependency and becomes erythematous?

Management of Critical Limb-Threatening Ischemia in a Diabetic Patient

This patient has critical limb-threatening ischemia (CLTI) and requires urgent vascular imaging and revascularization assessment within 24-48 hours to prevent amputation. 1

Clinical Recognition

The presentation is classic for CLTI:

• Rest pain (burning pain at night when lying flat) indicates inadequate perfusion even at rest 1
• Pain relief with dependency (hanging foot over bed) occurs because gravity improves distal blood flow 1
• Dependent rubor (foot becomes red when dependent) is pathognomonic for severe arterial insufficiency 1

This triad distinguishes CLTI from neuropathic pain, which typically worsens with dependency. 1

Immediate Diagnostic Workup

Obtain ankle-brachial index (ABI) immediately - an ABI <0.90 is diagnostic for lower extremity arterial disease (LEAD), though heavily calcified vessels in diabetes may yield falsely elevated readings (>1.40). 1

If ABI is >1.40 or non-compressible, obtain toe-brachial index (TBI) or duplex ultrasound, as medial arterial calcification is common in diabetes and renders ABI unreliable. 1

Perform duplex ultrasound as the first-line imaging method to assess anatomy and hemodynamic status of lower extremity arteries. 1

Obtain CT angiography or MR angiography to plan revascularization strategy, as this patient will likely need intervention. 1

Risk Stratification

Calculate the WIfI score (Wound, Ischemia, and foot Infection) to assess amputation risk - this is recommended for all CLTI patients. 1

Examine the foot carefully for skin breaks, ulceration, or infection, as diabetic patients with CLTI and peripheral neuropathy may have subtle presentations of foot infection. 1

Test for loss of protective sensation using 10g Semmes-Weinstein monofilament or 128 Hz tuning fork, as neuropathy combined with ischemia dramatically increases tissue loss risk. 1

Immediate Medical Management

Initiate antiplatelet therapy immediately - aspirin 100 mg daily is recommended for all symptomatic LEAD patients. 1

Consider dual pathway inhibition with low-dose rivaroxaban 2.5 mg twice daily plus aspirin 100 mg daily if no high bleeding risk exists, as this combination reduces cardiovascular events in LEAD. 1

Achieve LDL-C target <55 mg/dL (<1.4 mmol/L) or at least 50% reduction from baseline with high-intensity statin therapy, as diabetic patients with LEAD are at very high cardiovascular risk. 1

Optimize glycemic control to improve foot outcomes, though this should not delay revascularization. 1

Provide pain control with opioids if needed while awaiting revascularization. 1

Revascularization Strategy

Revascularization is indicated whenever technically feasible for limb salvage in CLTI - this is a Class I recommendation and should not be delayed. 1

Do not delay revascularization to screen for coronary or cerebrovascular disease if the patient is clinically stable, as time to intervention directly impacts limb salvage rates. 1

The choice between endovascular and surgical revascularization depends on arterial anatomy - diabetic patients typically have diffuse disease with severe involvement of tibial vessels, requiring imaging that includes foot run-off vessels. 1

Urgent Referral

Refer immediately to a multidisciplinary foot care team including vascular surgery, interventional radiology or cardiology, podiatry, and wound care specialists. 1

This referral should occur within 24 hours, as delays in CLTI management lead to irreversible tissue loss and amputation. 1

Critical Pitfalls to Avoid

Do not attribute symptoms to diabetic neuropathy alone - while neuropathy causes burning pain, it does not improve with dependency or cause dependent rubor. 1

Do not rely solely on palpable pulses - diabetic patients may have palpable pedal pulses despite significant arterial disease due to collateral flow. 1

Do not use beta-blockers as a contraindication - they do not adversely affect walking capacity or claudication symptoms and reduce cardiovascular events in PAD patients. 1

Do not delay intervention for "medical optimization" - while risk factor control is important, revascularization should proceed urgently to prevent amputation. 1

Post-Revascularization Care

After successful revascularization, the patient requires:

• Structured foot care education on daily inspection, proper footwear, and immediate reporting of new problems 1
• Therapeutic footwear with custom molded insoles to prevent pressure ulceration 1
• Regular follow-up every 1-3 months with the multidisciplinary team 1
• Continued antiplatelet therapy and statin indefinitely 1