Domain 1 of 5 · Vascular

Peripheral arterial disease assessment:Pulse, Pressures, Phases

Feel it. Measure it. Hear it. Three bedside steps, in this order.

An online teaching aid for clinicians. Real-life arterial sounds are only as good as the angle of the probe, and every finding should be read alongside the full vascular assessment.

Step 1PulseCan you feel the pulse points?
Step 2PressuresHow much blood is getting through, and what do you do about it?
Step 3PhasesWhat does the Doppler signal sound like?

First, the history

Vascular assessment is a head-to-toe assessment, and it needs a logical structure. Do this before you pick up a probe.

Presenting symptoms

Vascular Nurse“Intermittent claudication (IC) is easy to assess: its pain only on exercise, never at rest. Worse on an incline nine out of ten times, no symptoms on sitting, no symptoms in bed.”

Vascular Podiatrist“It is poorly reported outside of the vascular world. There is a tendency to refer all leg pain to screen out vascular involvement. Vascular assessment requires a logical structure.”

Symptom analysis tools

Stratified assessment tools will support your assessment, for example the Edinburgh Claudication Questionnaire.

Relevant information

Asking about other related symptoms will inform diagnosis against your differential, for example lower back pain, hip symptoms, or anything affecting the reporting of symptoms.

Vascular Nurse“We receive referrals for suspected IC saying ‘pain during night, pain whilst sat’ and you think ‘oh dear, it’s not vascular!’”

Past medical and social history

PAD-specific items include heart attack, stroke, diabetes, cholesterol, blood pressure, smoking, diet, exercise and weight management.

Medication

Anti-platelet, statin, anti-hypertensive and diabetes medication.

P1 · Step 1

Pulse palpation

Do this first, every time. Start at the femoral and work your way down. It is more logical.

1RadialWrist
2Common femoralGroin
3PoplitealBehind the knee
4Posterior tibialMedial ankle, behind the malleolus
5Dorsalis pedisTop of the foot, between the 1st and 2nd metatarsals

Pulses are either palpable or they are not. If they are not, further assessment should be arranged.

What to take from it

Palpate dorsalis pedis and posterior tibial on both feet. Absent or weak pulses raise suspicion of PAD before any pressure is taken.

P2 · Step 2

Pressures

An ankle brachial pressure index (ABPI) is a simple, non-invasive way to identify arterial insufficiency in a limb. It compares ankle and brachial systolic pressures.

Know when the ABPI cannot be trusted

In diabetes, medial arterial calcification can falsely raise the ABPI and hide significant ischaemia.
Where the ABPI is above 1.30 the vessels are incompressible. Disregard the result and use toe pressure or toe brachial index (TBI).
Use absolute pressures alongside the ratios, not instead of them. A ratio can look reassuring while the absolute pressure is low.
No single test excludes PAD. Always read the result against signs and symptoms.

Reference values

Bedside arterial assessment
Test	Interpretation
ABPI	Normal0.90 to 1.30 Abnormalbelow 0.90, indicates PAD Unreliableabove 1.30, incompressible: use toe pressure / TBI
TBI	Normal0.70 or above Abnormalbelow 0.70, indicates PAD
Toe pressure	Adequate60 mmHg or above: enough perfusion to heal a foot wound if other factors are optimised 30 mmHg or above raises the pre-test probability of healing by up to 30% Lowbelow 30 mmHg raises the pre-test probability of major amputation by about 20%
Ankle pressure	Normalabove 100 mmHg Urgentbelow 50 mmHg
WIfI ischaemia grade	0: ABI 0.80 or above, ankle above 100, toe pressure 60 or above 1: ABI 0.60 to 0.79, ankle 70 to 100, toe pressure 40 to 59 2: ABI 0.40 to 0.59, ankle 50 to 70, toe pressure 30 to 39 3: ABI 0.39 or below, ankle below 50, toe pressure below 30

What do I do with the result?

Pick the picture in front of you: is there an ulcer, and what are the ischaemic symptoms?

Draft for clinical review. This decision flow has not yet been signed off. Thresholds follow the IWGDF / ESVS / SVS 2023 guideline and the SVS WIfI classification. Do not use it as a clinical protocol.

1 · No ulcer, no ischaemic symptoms

Assess: ABPI alone should be accurate enough. There is no wound and no reported ischaemic symptom to complicate interpretation.

Low: ABPI below 0.90

Best medical therapy: antiplatelet, statin, smoking cessation, blood pressure and glucose optimisation.
No automatic referral. Document the risk factor and safety-net.

Normal: ABPI 0.90 to 1.30

No vascular action required.

IncompressibleIf the ABPI is above 1.30, treat the result as unreliable and go to toe pressure / TBI.

2 · Ulcer present, no ischaemic symptoms

Assess: The ABPI is reliable if the patient is non-diabetic. If diabetic, or the ABPI is above 1.30, use toe pressure / TBI for an accurate reading. WIfI ischaemia grading is relevant here.

Low: ABPI or TBI below 0.70, or toe pressure below 60 mmHg

Refer for arterial duplex.
Discuss with vascular surgery.

Normal ABPI / TBI

Monitor.
If the wound becomes chronic (stalled: less than 50% area reduction at 4 weeks), consider duplex.

3 · No ulcer, intermittent claudication

Assess: ABPI should be accurate and reliable as the first-line test. Add toe pressure / TBI where there is a history of diabetic foot ulcer, or where the ABPI is incompressible.

Low ABPI

Supervised exercise therapy plus best medical therapy.

Normal ABPI / toe pressure

Confirm that the pain is vascular claudication. If yes: supervised exercise therapy plus best medical therapy.
If no: look for other causes.

4 · No ulcer, ischaemic rest pain

Assess: ABPI plus toe pressure, and check that the reported symptoms are accurate. WIfI ischaemia grading is relevant here.

Low ABPI / toe pressure: WIfI ischaemia grade 2 or above (ABI below 0.60 or toe pressure below 40 mmHg)

Confirm rest pain clinically, then urgent same-day vascular review.

Normal ABPI / toe pressure: WIfI ischaemia grade 0 to 1

Not explained by bedside testing: discuss with vascular and consider further imaging.

5 · Ulcer present, ischaemic rest pain

Assess: ABPI plus toe pressure. Treat as chronic limb-threatening ischaemia (CLTI) until vascular review. WIfI ischaemia grading is relevant here.

CLTI until proven otherwiseDo not place this patient on a routine duplex waiting list.

Low ABPI / toe pressure

Urgent same-day vascular review.

Normal ABPI / toe pressure

Discuss further imaging and follow-up.
Vascular referral.

Infection present

Emergency department at the nearest vascular centre, within a 4-hour window.

Escalate the same day if any one of these is present

One is enough. They do not need to occur together.

ABPI below 0.5
Absolute ankle pressure below 50 mmHg
Absolute toe pressure below 30 mmHg
Non-audible Doppler signals
New gangrene or necrosis
New ischaemic rest pain within the last 2 weeks

Infection alongside any of these: emergency department at the nearest vascular centre, 4-hour window. Do not manage in a community clinic.

P3 · Step 3

Phases

Do you hear what I hear? The Doppler signal tells you about the flow behind the pressure.

Triphasic

Sharp forward peak, a brief reversal, then a small forward wave.

Adequate flow for healing

Biphasic

Sharp forward peak, then a reversal below the baseline, with no final forward wave.

Adequate flow for healing

Monophasic

A single, low, rounded forward wave.

Significant arterial disease

Schematic drawings, not real recordings. Terminology varies between services.

Listen. The recorded arterial sounds from the original site will be restored here, so you can hear each phase as well as see it.

What the experts say

The words clinicians use for the sound are not standardised, and that matters when you document and hand over.

Vascular Nurse“We just use three terms: triphasic, biphasic and monophasic.”

Vascular Podiatrist“I would use additional words, dull or strong monophasic, in a report, but it’s not a terminology I find anywhere that is standardised. It’s not used from a diagnostic point of view, it’s not overly supported in the literature. It’s used in the context of severity. I’m stating on that day what I heard.”

Vascular Sonographer“We’d go with dampened or pulsatile, but that’s because we can see the wave. We’d not just be looking at the sound. It’s the wave’s peak and distance.”

Vascular Podiatrist“We get a lot of monophasic pulses where it’s fairly sharp, and then we get the little domes, and I want some words to differentiate between the two, because it does differentiate the clinical decision sometimes. But it’s about the whole clinical picture.”

When the waveform may be all you have

In incompressible vessels (ABPI above 1.30) with an absent hallux, the Doppler waveform may be the only assessment of flow available. A non-audible signal is a same-day escalation criterion (see Pressures).

Now apply it to real patients.

Go to the case studies Test your ear

Sources for the reference values and decision flow

Fitridge R, et al. The intersocietal IWGDF, ESVS, SVS guidelines on peripheral artery disease in people with diabetes mellitus and a foot ulcer. J Vasc Surg 2023;78(5).
Mills JL Sr, et al. The Society for Vascular Surgery Lower Extremity Threatened Limb Classification System: risk stratification based on wound, ischemia, and foot infection (WIfI). J Vasc Surg 2014;59(1):220-34.
Conte MS, et al. Global vascular guidelines on the management of chronic limb-threatening ischemia. J Vasc Surg 2019;69(6S):3S-125S.
Sheehan P, et al. Percent change in wound area of diabetic foot ulcers over a 4-week period is a robust predictor of complete healing in a 12-week prospective trial. Diabetes Care 2003;26(6):1879-82.
NICE CG147: Peripheral arterial disease: diagnosis and management.