The Use of Handheld Doppler Ultrasound in Podiatry and Foot Health

An Overview of Applications, Benefits, and Best Practice

Introduction

Handheld Doppler ultrasound has become an essential tool in modern podiatry, revolutionising the way clinicians assess, diagnose, and monitor vascular conditions of the lower limbs. Highly portable and non-invasive, handheld Doppler devices empower podiatrists to make swift, informed decisions regarding their patients' vascular health, particularly in the realms of peripheral arterial disease (PAD), diabetic foot care, and pre-surgical evaluations. This document explores the principles behind handheld Doppler ultrasound, its clinical applications in podiatry, interpretation protocols, benefits, limitations, and emerging trends.

Principles of Doppler Ultrasound

At its core, Doppler ultrasound leverages the Doppler effect (noted by Christian Doppler 1803-53)—a change in frequency or wavelength of a wave relative to an observer moving relative to the wave source. In medical contexts, it involves emitting high-frequency sound waves that reflect off moving red blood cells within blood vessels. These reflections are detected and converted into audible signals or visual waveforms, enabling practitioners to assess blood flow characteristics in real time.

Handheld Doppler devices typically operate at frequencies between 2MHz and 10 MHz. the lower the MHz, the deeper the ultrasound travels so, 2MHz are use for foetal examination, 5MHz for larger arteries such as femoral, 8MHz for pedal pulses and 10MHz for digital arteries. The resulting audio signals, often described as “whooshing” or “swishing” sounds, provide valuable information about the presence, quality, and direction of blood flow.

Clinical Applications in Podiatry

Handheld Doppler ultrasound plays a pivotal role in several core aspects of podiatric practice:

1. Peripheral Arterial Disease (PAD) Screening

PAD is a common, often underdiagnosed condition in which narrowed arteries reduce blood flow to the limbs, especially the legs and feet. Early detection is crucial to prevent complications such as ulcers, gangrene, and potential limb loss. Handheld Doppler ultrasound is the cornerstone of non-invasive PAD screening in podiatry.

Podiatrists use Doppler devices to assess arterial pulses—namely the dorsalis pedis, posterior tibial and, where necessary, the peroneal artery—by detecting the presence, strength, and character of blood flow. The absence, diminution, or alteration of the normal triphasic waveform may indicate underlying arterial compromise, prompting further investigation or referral.

2. Ankle-Brachial Pressure Index (ABPI/ABI)

The ankle-brachial pressure index is a key diagnostic tool in vascular assessment. It compares the systolic blood pressure at the ankle with that in the arm, providing a quantitative measure of arterial perfusion. The handheld Doppler is instrumental in locating arterial pulses and accurately measuring the systolic pressures at these sites. ABI values below 0.9 typically suggest PAD, with lower values indicating more severe disease.

3. Diabetic Foot Care

People with diabetes are at heightened risk for developing foot complications due to neuropathy and vascular insufficiency. Regular assessment of peripheral circulation is a cornerstone of diabetic foot management. Handheld Doppler ultrasound allows podiatrists to monitor blood flow, detect early signs of vascular impairment, and tailor treatment plans to reduce the risk of ulcers, infections, and amputations.

4. Pre-surgical and Wound Assessment

Before performing surgical interventions—ranging from minor procedures to major reconstructive surgeries—podiatrists must ensure adequate vascular supply to support healing. Handheld Doppler assessment provides a rapid, reliable means to verify arterial patency and flow quality, helping to minimise post-operative risks.

In wound management, Doppler ultrasound assists in distinguishing between arterial and venous ulcers, monitoring healing progress, and guiding referrals to vascular specialists when necessary.

5. Monitoring and Follow-Up

Beyond initial diagnosis, handheld Doppler devices are invaluable for ongoing monitoring of patients with established vascular disease. Regular assessment helps to track disease progression, gauge response to interventions, and inform changes in management.

Technique and Best Practices

Effective use of handheld Doppler ultrasound requires familiarity with both the technology and the nuances of vascular anatomy. Key steps include:

·       Patient Preparation: The patient should be relaxed, in a supine or comfortable seated position with feet appropriately exposed. Environmental factors, such as room temperature, should be controlled to prevent vasoconstriction.

·       Probe Positioning: The Doppler probe is placed at a 45 degree angle over the target artery pointing toward the flow of blood. Using ultrasonic gel to ensure good acoustic contact. Gentle, steady pressure is essential.

·       Pulse Identification: The clinician listens for characteristic audio signals—triphasic (normal), biphasic, or monophasic—while noting pulse location, timing, and quality.

·       Waveform Interpretation: Some advanced Dopplers provide visual waveforms, which can be recorded and compared over time.

·       Documentation: Accurate records of findings, including pulse strength and waveform character, are vital for continuity of care.

Interpretation of Doppler Signals

Interpretation of Doppler ultrasound findings is both an art and a science. Audio signals range from crisp, sharp “whooshes” of triphasic flow (indicative of healthy arteries) to muffled, prolonged, or absent signals that may signify pathology. Key interpretations include:

·       Triphasic waveform: Normal in healthy arteries, representing brisk systolic flow, brief reversal in early diastole, and a final forward component. There are three sounds to hear. This has often been described as three syllables in ” Sausages”. Saus-ag-es – three sounds.

·       Biphasic waveform: Often seen with mild to moderate arterial disease. There are two sounds to hear, often described by the word ‘bacon’ , that’s ba-con. Two sounds.

·       Monophasic waveform: Suggests severe arterial compromise and warrants urgent attention. A single noise, described as ‘Eggs’. One sound.

·       Absent flow: May imply complete occlusion or technical error (e.g., poor probe contact).

Benefits of Handheld Doppler Ultrasound

The popularity of handheld Doppler devices in podiatry is driven by several compelling advantages:

·       Non-invasive and painless: No needles or incisions are required, making it comfortable for patients.

·       Immediate results: Real-time assessment supports rapid decision-making.

·       Portability: Compact and battery-operated, these devices are ideal for use in clinics, hospitals, and even home visits.

·       Cost-effectiveness: Compared to more advanced imaging modalities, Doppler ultrasound is affordable and accessible.

·       Enhanced diagnostic confidence: When used correctly, Doppler assessment improves diagnostic accuracy, patient outcomes, and continuity of care.

Limitations and Pitfalls

Despite its many benefits, handheld Doppler ultrasound is not without limitations:

·       Operator dependency: Accurate interpretation depends on practitioner skill and experience.

·       Technical limitations: Obesity, oedema, or calcified vessels can impede signal acquisition.

·       Lack of anatomical detail: Unlike duplex ultrasonography, handheld Doppler does not provide imaging, only flow information.

·       Subjectivity: Audio interpretation can be subjective; visual waveforms and digital recording help mitigate this but are not always available.

Training and Competency

To maximise the utility of handheld Doppler ultrasound, podiatrists should undergo formal training in device operation, vascular anatomy, and waveform interpretation. Continuing education and regular skills refreshers are recommended, especially as new technologies and devices emerge.

Emerging Trends and Future Directions

Devices now feature digital displays, mobile app integration, automated waveform analysis, and even portable duplex imaging. Artificial intelligence is beginning to play a role in automated interpretation and triage, promising to further streamline vascular assessments.

In an era of increasing chronic disease burden—particularly diabetes and vascular disease—the role of Doppler ultrasound in podiatry is set to expand. Martin Fox, vascular podiatrist in Manchester Foundation Trust promotes the use of handheld Doppler and encourages the clinical application of the WiFI* stratification process (Wound, Ischaemia and Foot Infection) to determine amputation risk.

Conclusion

Handheld Doppler ultrasound has become a mainstay of podiatric care, enabling accurate, non-invasive assessment of vascular status in the lower limbs. From early detection of PAD to tailored diabetic foot care and pre-surgical evaluation, its applications are diverse and clinically invaluable.

 

References

*Cerqueira LO, Duarte EG, Barros ALS, Cerqueira JR, de Araújo WJB. WIfI classification: the Society for Vascular Surgery lower extremity threatened limb classification system, a literature review. J Vasc Bras. 2020 May 8;19:e20190070. doi: 10.1590/1677-5449.190070. PMID: 34178056; PMCID: PMC8202158.