Clinical Vascular Examination and Physiologic Testing
Clinical vascular examination and physiologic testing as the first triage step in suspected peripheral artery, carotid, aneurysmal, and venous disease. The chapter frames history, inspection, pulses, ABI, segmental pressures, and the laboratory request so the right patient enters the right pathway.
Consult corner: A bedside consult-style discussion focused on what the clinician should decide next and what not to overinterpret.
Choose the hostsHistory, inspection, pulses, and first-line testing
The clinical vascular examination begins before the vascular laboratory request is written. The surgeon’s first task is to decide whether the patient belongs in a targeted peripheral artery disease pathway, not to order a generic “vascular panel.” Lower-extremity PAD becomes more prevalent with advancing age, rising from approximately 5% in middle-aged adults to more than 18% among the oldest adult groups in high-income cohorts; it shares the major atherosclerotic risk factors of smoking, diabetes mellitus, hypertension, and dyslipidaemia with coronary and cerebrovascular disease. A careful clinic history should therefore identify age, smoking history, diabetes, hypertension, dyslipidaemia, prior coronary or cerebrovascular disease, exertional leg symptoms, rest pain, ulceration, and previous vascular interventions, while avoiding indiscriminate testing of low-risk asymptomatic adults.
Classic intermittent claudication remains important, but it is not the only symptomatic expression of PAD. Many patients with ABI-defined PAD report atypical exertional leg symptoms or no classic claudication, so the history should deliberately ask about walking distance, pace, grade, reproducibility, relief with rest, limitation by hip, knee, back, or pulmonary disease, and whether the patient has unconsciously reduced activity to avoid symptoms. This matters because a patient with “no claudication” may still have walking impairment, abnormal limb haemodynamics, and high systemic cardiovascular risk.
The bedside examination should be structured and reproducible. Inspect both legs and feet for dependent rubor, pallor on elevation, trophic skin change, ulceration, tissue loss, temperature asymmetry, deformity, and signs that would make a normal resting ABI misleading, particularly diabetes, advanced age, renal failure, or suspected medial arterial calcification. Palpate femoral, popliteal, dorsalis-pedis, and posterior-tibial pulses bilaterally, listen for femoral bruits when appropriate, and document whether each pulse is normal, reduced, absent, or difficult to assess. NICE describes a diagnostic pathway that combines symptom review, leg and foot examination, femoral–popliteal–foot pulse assessment, and ABPI rather than treating the ABPI as a stand-alone number.
The initial decision point is whether resting physiologic testing is indicated. Resting ABI is appropriate when history or examination suggests PAD, and targeted case finding is supported for older patients and for patients with diabetes or smoking exposure. The 2016 AHA/ACC guideline identified age 65 years and older, or age 50 years with diabetes or smoking history, as thresholds for ABI consideration in targeted assessment, while advising against population-wide ABI screening in asymptomatic adults without atherosclerotic risk factors. The practical record should state the indication: “exertional calf pain with diminished pedal pulses,” “age over 65 with atherosclerotic risk factors,” or “diabetes and smoking history with abnormal foot examination,” rather than merely “screening ABI.”
A normal pulse examination does not end the evaluation when the history is persuasive, and an abnormal pulse examination should not be left unquantified. Current PAD evaluation begins with history, vascular examination, and resting physiologic testing; toe pressure or TBI, segmental pressures, pulse-volume recordings, and exercise ABI are used when the resting ABI is unreliable or discordant with symptoms. Cross-sectional imaging should not be treated as the first diagnostic answer for routine suspected PAD; it is most useful after the surgeon has established that haemodynamics and symptoms justify anatomic definition.
The ABPI or ABI technique must be documented because the ratio is only interpretable when the measurement method is known. NICE describes supine rest, measurement in both arms, ankle pressures from posterior tibial and dorsalis pedis or peroneal arteries with a manual Doppler, documentation of foot signals, and use of the highest ankle pressure divided by the highest arm pressure. In a vascular surgery note, “right ABI 0.72” is incomplete; “right ABI 0.72, highest ankle pressure divided by highest brachial pressure, DP and PT Doppler signals recorded” is clinically usable.
The first-line lower-limb physiologic test should answer three questions: is PAD present, is the ABI reliable, and is the level of disease suggested well enough to select the next test? Segmental limb pressures using high-thigh, low-thigh, calf, and ankle cuffs can localise disease across iliofemoral, femoropopliteal, and infrapopliteal segments. An adjacent-cuff systolic pressure gradient of at least 20 mmHg is generally interpreted as haemodynamically significant disease at the intervening level, but high-thigh cuff artefact and bilateral inflow disease can mislead the unwary; pulse-volume recordings help reconcile pressure data when vessels are calcified or cuffs are unreliable.
Once physiologic testing confirms PAD and the patient is a revascularization candidate, imaging selection becomes a planning decision rather than a diagnostic reflex. Duplex ultrasound and CT angiography are rated as usually appropriate first-line modalities for lower-extremity claudication revascularization planning, while MR angiography is usually appropriate when contrast-induced acute kidney injury risk or cumulative radiation exposure is a concern. Catheter angiography should generally be reserved for cases proceeding to intervention or for unresolved anatomy after noninvasive imaging.
The general vascular examination should also detect disease outside the presenting limb. Men aged 65–75 years who have ever smoked should be offered one-time abdominal ultrasound screening for abdominal aortic aneurysm, with AAA defined as an aortic diameter of 3.0 cm or greater. This is not a substitute for lower-limb PAD assessment, but it is a common high-value opportunity in the vascular clinic when the same patient presents with atherosclerotic risk factors.
The examination is also a prevention encounter. An abnormal ABI is not merely a limb test; low ABI and high ABI are both associated with approximately doubled 10-year all-cause and cardiovascular mortality in pooled community cohorts, and ABI can reclassify cardiovascular risk in intermediate-risk patients. The surgeon should therefore record both the limb implication and the systemic implication: abnormal haemodynamics justify PAD diagnosis and limb-directed decisions, while the same result should intensify cardiovascular risk reduction regardless of symptom severity.
Initial bedside PAD assessment is now handled in prose: history, pulse examination, wounds, diabetes/renal risk, and exertional symptoms determine whether ABI/ABPI is the first physiologic test.
Anatomic imaging should follow a physiologic question: duplex, CTA, or MRA is ordered when the result will change revascularization planning, not as a substitute for bedside assessment and ABI/TBI.
ABI and rescue physiology
The resting ABI is the central first-line physiologic test because it is simple, reproducible when performed correctly, and prognostically important. The AHA method calculates ABI by dividing the higher ankle systolic pressure from dorsalis-pedis and posterior-tibial signals by the higher of the two brachial systolic pressures, with both arms and both ankles measured. This calculation should be stated in the report because alternative methods produce different ratios and can shift a patient across diagnostic thresholds.
The diagnostic bands should be applied deliberately. A resting ABI of 1.00–1.40 is normal by AHA criteria; 0.91–0.99 is borderline; 0.90 or lower is abnormal and diagnostic of PAD; and greater than 1.40 indicates noncompressible, usually calcified arteries and is unreliable for diagnosing or excluding PAD by ABI alone. The report should therefore avoid vague language such as “mildly reduced circulation” and should instead state the category and consequence: “ABI 0.84, abnormal, consistent with PAD,” or “ABI 1.48, noncompressible; ABI is nondiagnostic and toe testing is required.”
An ABI of 0.90 or lower confirms PAD, but it does not by itself determine revascularization. The next decision depends on symptoms, functional limitation, tissue loss, treatment goals, and whether anatomic imaging would change management. Conversely, an ABI in the normal range does not exclude PAD when symptoms are typical, especially in early disease, proximal disease, or circumstances in which resting haemodynamics have not been sufficiently stressed.
Borderline ABI requires discipline. A value between 0.91 and 0.99 should not be dismissed when the patient describes exertional symptoms or has abnormal pulses. In symptomatic patients with borderline ABI, current guidance supports additional physiology—most often exercise ABI or TBI—before concluding that PAD is absent. Borderline values can also move with cuff size, patient position, temporary hemodynamic variation, and operator technique, so the clinical context must remain visible in the interpretation.
Noncompressible ABI is a common trap in patients with diabetes, advanced age, end-stage renal disease, or medial arterial calcification. An ABI greater than 1.40 is not reassuring; it means the cuff has failed to compress the artery adequately, and flow-limiting disease may still be present. The appropriate rescue test is toe-brachial index or toe pressure assessment, because digital arteries are less often noncompressible, and a TBI of 0.70 or lower supports the diagnosis of PAD when ABI is unreliable.
Exercise ABI is the rescue test for the symptomatic patient whose resting ABI is normal or borderline. A standardized treadmill protocol should be used when the patient can walk safely; the purpose is to reproduce symptoms and unmask a hemodynamic fall that is absent at rest. A post-exercise ankle systolic pressure drop of at least 20% from baseline, or a post-exercise ABI decrease of at least 20% from baseline, is interpreted as evidence of exercise-unmasked PAD. The report should include baseline pressures, post-exercise pressures, timing of measurement, symptoms produced, walking limitation, and the percent change.
When treadmill testing is not feasible, the surgeon should still seek physiologic confirmation rather than jumping directly to anatomic imaging in every case. The appropriate-use framework recognises alternatives such as reactive hyperaemia or other validated laboratory protocols when standard treadmill exercise is contraindicated or impractical. The key is not the specific brand of provocation but whether the laboratory uses a standardized protocol and reports interpretable pre- and post-provocation haemodynamics.
Segmental pressures add localisation to diagnosis. A multilevel cuff protocol using high thigh, low thigh, calf, and ankle pressures can suggest iliofemoral, femoropopliteal, or infrapopliteal disease before imaging. A pressure gradient of 20–30 mmHg or more between adjacent cuffs is generally treated as haemodynamically significant at the intervening segment; some laboratories use 30 mmHg to improve specificity. The surgeon should know the laboratory criterion and should not overinterpret a single thigh gradient when cuff artefact, obesity, pain, or bilateral inflow disease could distort the result.
Pulse-volume recordings are especially useful when pressure measurements are unreliable. In calcified vessels, pressure ratios may be falsely high, while waveform morphology can still show dampening consistent with inflow or outflow disease. The interpretation should integrate ABI, TBI, segmental pressures, and waveform information rather than allowing one discordant number to override the bedside picture.
The prognostic meaning of ABI should be communicated clearly. A low ABI of 0.90 or below is associated with approximately doubled 10-year all-cause and cardiovascular mortality compared with ABI 1.10–1.40 in pooled cohorts, and a high ABI above 1.40 carries similar adverse prognostic weight despite reflecting noncompressible arteries rather than direct stenosis measurement. Thus both “low” and “too high to compress” ABI results should trigger serious cardiovascular risk management, not merely limb imaging.
Anatomic imaging follows physiology when intervention is being considered. For intermittent claudication patients who are candidates for revascularization, duplex ultrasound and CTA are usually appropriate first-line planning tests; MRA is usually appropriate when renal function or radiation considerations make CTA less attractive, although stent compatibility and artefact must be considered. Catheter angiography should be used as a diagnosis-intervention encounter or when noninvasive imaging cannot resolve anatomy, not as a routine diagnostic substitute for ABI, TBI, and exercise testing.
Nondiagnostic ABI is rescued by exercise ABI, segmental pressures, toe pressures/TBI, and waveform assessment; the choice depends on symptoms and vessel compressibility.
Exercise ABI adds value when resting ABI is borderline or normal despite exertional symptoms; the result is interpreted with symptom reproduction and post-exercise pressure change.
Result quality and interpretation traps
The most common error in physiologic testing is treating numbers as independent of technique. Bilateral brachial pressures, correct cuff selection, supine rest, Doppler signal identification, and documented calculation method all affect ABI validity. A report that omits arm pressures, ankle artery used, waveform quality, or the calculation method should be interpreted cautiously, particularly when the result conflicts with the history or pulse examination.
Interarm systolic pressure difference is not a nuisance variable; it is part of the vascular examination. A difference of at least 10 mmHg is associated with PAD and should prompt lower-extremity PAD screening when clinically appropriate, while a difference of at least 15 mmHg is associated with subclavian stenosis, cerebrovascular disease, and increased cardiovascular and all-cause mortality. Because single-occasion differences can be technique-related, the finding should be repeated or confirmed with standardized measurement, but it should not be ignored.
The higher brachial pressure is used for ABI calculation to reduce the risk that occult subclavian or brachiocephalic disease falsely elevates the index on the affected side. This is why both arms must be measured at the initial examination. A trainee who measures only one arm may produce a falsely reassuring ABI, particularly in the same patient whose interarm difference should have triggered concern for proximal upper-extremity disease.
A normal ABI is not always a normal vascular assessment. Patients with typical exertional symptoms may have normal resting haemodynamics but abnormal post-exercise pressures. Patients with calcified vessels may have a falsely normal or elevated ABI. Patients who have reduced their walking speed or distance may describe “no symptoms” because they no longer stress the limb. These traps are why symptom analysis, pulse examination, ABI category, toe testing, exercise ABI, and waveform data must be interpreted together.
A high ABI is not benign. ABI greater than 1.40 indicates noncompressible arteries and is unreliable for PAD exclusion; in pooled cohort data, high ABI is associated with approximately doubled 10-year all-cause and cardiovascular mortality compared with the reference ABI range. The practical response is twofold: obtain alternative hemodynamic testing such as TBI or duplex-supported assessment, and treat the patient as high cardiovascular risk.
Segmental pressures can mislocalise disease when the laboratory and surgeon forget the limitations of cuffs. High-thigh pressures are vulnerable to artefact, bilateral inflow disease can mask side-to-side comparisons, and noncompressible arteries can produce misleadingly high values. A ≥20 mmHg adjacent-cuff gradient should be reported as a localising sign, but it should be reconciled against pulse-volume recordings and, when treatment is contemplated, against duplex, CTA, or MRA.
Thresholds should be laboratory-governed, not improvised at the workstation. Some laboratories use a ≥20 mmHg adjacent-cuff gradient as the lower bound for haemodynamically significant disease; others use ≥30 mmHg to improve specificity. The report should state the criterion, and the medical director should ensure that the criterion is applied consistently within a documented protocol.
Laboratory accreditation and professional performance standards matter because physiologic testing is operator-dependent. Accredited vascular testing facilities are expected to maintain written diagnostic criteria, appropriate instrumentation, technologist qualifications, laboratory organization, and quality-assurance processes. These standards do not create disease thresholds by themselves, but they support reproducibility and allow the surgeon to judge whether a result can safely drive imaging, intervention, or surveillance decisions.
Professional ultrasound performance guidance should be viewed as the floor, not the ceiling. SVU performance guidelines describe essential examination steps and quality-assurance expectations for tests such as ABI, TBI, segmental pressures, exercise testing, and pulse-volume recordings; they are a basis for laboratory-specific protocols rather than a replacement for medical-director governance. The surgeon should know how the local laboratory performs each test, because the same phrase—“exercise ABI,” “segmental pressures,” or “toe pressures”—can conceal meaningful protocol variation.
Jurisdictional differences should be acknowledged without confusing the patient record. NICE, European, and US pathways all support structured history, vascular examination, and noninvasive physiologic testing, but wording and recommendation frameworks differ. A clean clinical note should therefore document the patient-specific indication, method, threshold, and next step rather than relying on a vague statement that the patient “meets guideline criteria.”
Population prevalence is useful for deciding whom to test, but it does not diagnose the patient in front of the surgeon. PAD prevalence increases with age and varies by definition, geography, and ABI methodology; global estimates are constrained by country-level data quality and measurement differences. The bedside implication is targeted vigilance, not blanket testing: older age and atherosclerotic risk factors lower the threshold for ABI, while low-prevalence, low-risk groups should not be swept into indiscriminate screening.
Physiologic traps—calcified tibial vessels, multilevel disease, edema, wounds, poor cuff technique, and discordant symptoms—should be documented in the report rather than hidden behind a single number.
Persistent interarm systolic pressure differences are handled in the compact pressure-threshold table and should prompt repeat measurement and consideration of proximal upper-extremity disease.
Minimum ABI/TBI reporting elements are prose requirements: indication, bilateral arm pressures, ankle artery used, toe pressure when needed, waveform quality, and study limitations.
Clinical integration, follow-up, and evidence boundaries
The clinical endpoint of examination and physiologic testing is a documented decision. After the first visit, the note should state whether PAD is confirmed, excluded by current testing, unresolved because ABI is nondiagnostic, or physiologically present but not yet anatomically mapped. Each category implies a different next step: confirmed PAD triggers cardiovascular risk reduction and symptom-based management; nondiagnostic ABI triggers TBI or waveform-supported testing; typical symptoms with normal or borderline ABI trigger exercise ABI; and revascularization candidacy triggers anatomic imaging.
A borderline ABI is a follow-up problem, not a reassurance script. ABI 0.91–0.99 sits between normal and abnormal, and in a symptomatic patient it should lead to exercise ABI or TBI before the surgeon concludes that PAD is absent. The follow-up instruction should be explicit: return after provocation testing, report worsening walking impairment, and seek reassessment if rest pain, ulceration, or tissue loss develops.
A noncompressible ABI also requires follow-up clarity. The patient should not be told that leg circulation is normal when ABI is greater than 1.40; the correct message is that the arteries could not be compressed reliably and that toe-based or waveform-based testing is needed. Because high ABI carries adverse cardiovascular prognostic meaning, the visit should also close the loop on systemic risk management rather than waiting for an anatomic study to “prove” stenosis.
When physiology confirms PAD but symptoms are mild or atypical, the surgeon should separate diagnosis from intervention. An abnormal ABI or TBI establishes the presence of disease and justifies risk-factor treatment, but imaging for revascularization planning is most appropriate when symptoms, functional limitation, or limb findings make a procedure plausible. Duplex ultrasound, CTA, or MRA should be selected according to comorbidity, renal function and radiation considerations, stent compatibility, local expertise, and the anticipated treatment question.
Follow-up after an abnormal physiologic study should also address the whole patient. Low ABI and high ABI each signal increased long-term cardiovascular mortality, so the result should be integrated into global atherosclerotic risk assessment and prevention. The AHA cardiovascular-health framework of smoking status, body mass index, physical activity, diet, total cholesterol, blood pressure, and fasting plasma glucose gives a practical structure for risk-factor counseling in the vascular clinic.
The surgeon should be cautious when using older vocabulary. TASC II supplied useful historical language for PAD lesion categories and classic claudication or critical limb ischemia framing, but current diagnostic thresholds should rely on contemporary ABI methodology and current PAD guideline pathways. In a modern chapter or patient record, TASC terminology may help describe historical anatomy or prior reports, but it should not override current physiologic thresholds or current testing logic.
Evidence boundaries must be visible in clinical reasoning. Population-based ABI mortality data support prognosis and risk reclassification, especially in intermediate-risk patients, but they do not dictate limb intervention. Segmental pressure gradients localise hemodynamic disease, but they can be confounded by cuff artefact and bilateral inflow disease. Exercise ABI thresholds can confirm exercise-unmasked PAD, but protocol and timing influence the result. The mature interpretation is therefore probabilistic and integrated: bedside story, pulse examination, physiologic category, waveform pattern, and treatment intent are read together.
The final report should make later treatment planning easier. A useful physiologic summary includes the clinical indication, ABI category, whether vessels are compressible, TBI result when obtained, segmental gradients and laboratory threshold, waveform interpretation, symptom reproduction during exercise, and whether the findings are sufficient to proceed to anatomic imaging. This format allows the next surgeon—or the same surgeon six months later—to understand whether a change in symptoms represents disease progression, a testing artefact, or a new treatment indication.
Follow-up action follows the ABI/TBI triage table: abnormal physiology plus symptoms or tissue loss supports vascular work-up, while stable symptoms without a treatment decision should not trigger anatomy-only imaging.
Documentation after physiologic testing should state indication, method, thresholds used, waveforms, and limitations so the next clinician can tell whether a changed value reflects disease or technique.
Prognostic ABI data remain important for cardiovascular risk, but they do not need a separate decision aid here; they should inform risk-factor treatment and follow-up intensity.
Documentation after physiologic testing should state indication, method, thresholds used, waveforms, and limitations so the next clinician can tell whether a changed value reflects disease or technique.
Prognostic ABI data remain important for cardiovascular risk, but they do not need a separate decision aid here; they should inform risk-factor treatment and follow-up intensity.
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