What is the workup for peripheral arterial disease (PAD) of the foot to assess circulation?

From the Guidelines

A foot circulation workup should begin with a thorough history and physical examination, focusing on risk factors like diabetes, smoking, hypertension, and symptoms such as claudication, rest pain, or tissue changes, as recommended by the most recent guidelines 1. The examination should include assessment of pulses (dorsalis pedis and posterior tibial), skin temperature, color, capillary refill, and presence of ulcers or gangrene.

• Key components of the physical examination include:
  • Assessment of lower-extremity pulses
  • Capillary refill time
  • Rubor on dependency
  • Pallor on elevation
  • Venous filling time
• The ankle-brachial index (ABI) is the initial diagnostic test, with values below 0.9 indicating peripheral artery disease (PAD), however, it should be interpreted carefully, as it is known to be inaccurate in people with diabetes due to noncompressible vessels 1.
• For diabetic patients or those with calcified vessels, toe-brachial index may be more accurate, with toe systolic blood pressures <30 mmHg suggestive of PAD and an inability to heal foot ulcerations 1.
• Further non-invasive testing includes segmental pressure measurements, pulse volume recordings, and duplex ultrasound to locate and quantify stenosis, as outlined in the guidelines 1.
• Advanced imaging like CT angiography or MR angiography may be necessary for surgical planning, particularly in cases where revascularization is being considered 1.
• Laboratory tests should include lipid profile, HbA1c, renal function, and complete blood count, to assess overall cardiovascular risk and guide management decisions.
• Management depends on severity but typically includes risk factor modification (smoking cessation, diabetes control), antiplatelet therapy (aspirin 81mg daily or clopidogrel 75mg daily), statins (atorvastatin 40-80mg daily), and supervised exercise programs, with severe cases requiring revascularization procedures 1.

From the Research

Foot Circulation Workup

• A thorough physical examination is essential in assessing foot circulation, including inspection, palpation, range of motion, and special tests when applicable 2
• The ankle-brachial index (ABI) is a commonly used test to diagnose peripheral artery disease (PAD), but its accuracy can be limited in patients with noncompressible vessels or those with diabetes and chronic kidney disease 3
• The ABI may underestimate the severity of PAD in these patients, and additional tests such as the toe-brachial index (TBI) may be necessary to confirm the diagnosis 3
• Clinical assessment of peripheral circulation can be done noninvasively through physical examination, including inspecting the skin for pallor or mottling, and measuring capillary refill time on finger or knee 4
• The ABI has been associated with a higher cardiovascular risk and mortality in patients with type 2 diabetes mellitus, and its measurement can help identify those at high risk of PAD 5
• The US Preventive Services Task Force has found insufficient evidence to determine the balance of benefits and harms of screening for PAD with the ABI in asymptomatic adults 6

Diagnostic Considerations

• A broad differential diagnosis should include disorders of bones, joints, muscles, neurovasculature, and surrounding soft tissue structures 2
• Patients with PAD are at increased risk for cardiovascular disease events, and a comprehensive assessment of cardiovascular risk is essential in managing these patients 6, 5
• The presence of diabetes and chronic kidney disease can affect the accuracy of the ABI and the diagnosis of PAD, and additional tests and considerations may be necessary in these patients 3, 5

Management and Treatment

• Effective management of foot circulation disorders requires a thorough diagnosis and assessment of the underlying causes 2
• Treatment of PAD may involve supervised exercise and physical therapy, as well as medical management of cardiovascular risk factors 6, 5
• Further research is needed to determine the most effective treatments and management strategies for patients with foot circulation disorders, particularly those with diabetes and chronic kidney disease 3, 5