Pulse Volume Recording

For physicians

What is measured

Segmental volume plethysmography. Pressure cuffs applied to the limb detect the small fluctuations in limb volume that occur with each cardiac cycle, and the resulting waveform is assessed for upstroke, amplitude, contour and the presence or loss of the dicrotic notch.

Why it earns a place beside the index

Ankle-brachial indices can fall within the normal range in the presence of moderate to severe disease when arterial calcification is present. Pulse volume recording has higher sensitivity in that setting, and because Doppler sensitivity is itself diminished by calcification, volume plethysmography is usually the practical option for obtaining peripheral arterial waveforms in these patients.

Reading it

Waveform morphology is qualitative and comparative: assess side-to-side and level-to-level rather than against an absolute. A damped waveform with a normal or elevated index points at incompressibility rather than at a normal artery. A normal waveform in a symptomatic limb redirects the differential toward neuropathic, musculoskeletal or venous causes. Interpreting the report.

Where it fits

Acquired in the same sitting as the ankle-brachial index and the digital pulse waveform; the three are read together, never separately.

Evidence and limitations

Written for a reader who wants the literature rather than the summary. Where the evidence is thin we say so and give both sides, and where a claim is mechanistic rather than demonstrated we label it as such.

Mechanism

Volume plethysmography records the small change in limb volume produced by each arterial pulse. Because it measures a volume change rather than the pressure needed to occlude a vessel, it does not depend on the artery being compressible — the property that makes the ankle-brachial index unreliable in medial arterial calcification. Waveform contour, upstroke and the presence or loss of the dicrotic notch reflect inflow and compliance downstream of any stenosis.

What the evidence shows

The clinical argument rests on the failure mode of its companion test. A 2022 systematic review of 23 studies of bedside diagnostics in patients prone to medial arterial calcification — mostly older, male and diabetic — found that an ankle-brachial index below 0.90 was useful for diagnosing peripheral artery disease but poor at excluding it, and that toe pressure and the toe-brachial index shared that weakness. Loss of a triphasic Doppler waveform was the one measure reliable for exclusion, with a negative likelihood ratio of 0 to 0.09, although validated in only two studies.

That is a waveform-based finding, and it is the same principle pulse volume recording relies on: morphology carries information that an occlusion pressure loses when the vessel will not occlude.

Limitations of that evidence

• The supporting evidence is thin and indirect. The strongest exclusion data in that review is for continuous-wave Doppler waveform analysis, in two studies, not for segmental volume plethysmography specifically.
• Interpretation is qualitative. Waveforms are read comparatively — side to side, level to level — rather than against an absolute threshold, which makes reader agreement a real variable and formal diagnostic accuracy hard to pin down.
• Methodological quality across this literature is poor, with risk of bias identified in 20 of 23 studies.
• Cuff placement, limb temperature and rest period all alter amplitude.

What remains uncertain

How much weight a damped waveform should carry when the index is normal has not been settled quantitatively, and the honest framing is the one the systematic review itself used: no single bedside test should be relied on in this population. That is an argument for acquiring several measurements in one sitting and reading them against each other, and for escalating to imaging when the picture and the symptoms disagree — not an argument for treating any one of them, including this one, as definitive.