Can a Transcutaneous Bilateral Implant (TBI) be performed on a patient with pedal edema and absent pedal pulses?

Performing TBI in Patients with Pedal Edema and Absent Pedal Pulses

Yes, a toe-brachial index (TBI) should be performed in patients with pedal edema and absent pedal pulses, as it is specifically recommended for cases where arterial assessment is complicated by noncompressible vessels or edema. 1

Rationale for TBI in Patients with Pedal Edema and Absent Pulses

• TBI is the recommended diagnostic test when pedal pulses cannot be adequately assessed due to edema, as it provides a more reliable measure of distal perfusion than ankle-brachial index (ABI) in these circumstances 1
• Pedal edema can mask palpable pulses and interfere with accurate ABI measurement, making TBI a more reliable alternative for assessing peripheral arterial disease (PAD) 1
• TBI is specifically indicated when arterial calcification (which can present with noncompressible vessels) or edema makes standard ABI measurements unreliable 1
• The American College of Cardiology/American Heart Association guidelines specifically recommend TBI for patients with suspected PAD when standard assessments are compromised 1

Technical Considerations for TBI in Patients with Edema

• TBI should be performed with waveform analysis to provide additional diagnostic information beyond the numerical index 1
• A TBI value ≤0.70 is considered abnormal and diagnostic of PAD, even when ABI cannot be reliably measured due to edema 1
• When performing TBI in patients with edema, ensure proper positioning and careful placement of the toe cuff to minimize the effect of fluid accumulation on measurement accuracy 1, 2
• TBI measurements should be taken in a warm room to prevent arterial vasoconstriction, which is especially important in patients with compromised circulation 1

Additional Assessment Recommendations

• In patients with pedal edema and absent pulses, consider supplementing TBI with transcutaneous oxygen pressure (TcPO2) and/or skin perfusion pressure (SPP) measurements for a more comprehensive assessment of tissue perfusion 1
• For patients with suspected chronic limb-threatening ischemia (CLTI), TBI with waveforms should be combined with other perfusion assessments to determine the likelihood of wound healing and need for revascularization 1
• Segmental pressures with pulse volume recordings (PVR) and/or Doppler waveforms can help delineate the anatomic level of PAD in patients with chronic symptomatic disease 1

Clinical Implications and Management

• Patients with absent pedal pulses and edema should be evaluated for both vascular and non-vascular causes of their symptoms 2
• If TBI confirms PAD (≤0.70), further anatomic assessment with duplex ultrasound, CTA, MRA, or invasive angiography may be indicated if revascularization is being considered 1
• Patients with confirmed PAD should receive guideline-directed management including risk factor modification, antiplatelet therapy, and consideration for revascularization based on symptom severity 2
• Be aware that pedal edema may have multiple etiologies, including heart failure, which can coexist with PAD and complicate management 3

Pitfalls and Caveats

• Do not rely solely on pulse palpation in patients with edema, as this physical finding can be unreliable; objective vascular testing with TBI is essential 2
• Avoid delaying appropriate diagnostic testing in patients with absent pulses and edema, as timely diagnosis is critical for limb preservation in severe cases 4
• Be aware that certain medications (like calcium channel blockers) can cause pedal edema that may complicate assessment of vascular status 5
• Remember that TBI is more reliable than ABI in patients with diabetes, chronic kidney disease, and advanced age due to the lower incidence of digital artery calcification compared to ankle vessels 1