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Diagnostic vascular tests to diagnose PAD

The diagnosis of Peripheral Arterial Disease (PAD) should always be confirmed using objective vascular testing. Ankle-Brachial Index (ABI) is the most commonly used test. An ABI is simple to perform but unfortunately not always reliable. Patients suffering from diabetes, renal disease or Critical Limb Ischemia (CLI) often show falsely elevated ABI values due to arterial calcifications. Furthermore, the outcome of a chronic wound is not only dependent on the macrovascular status but also the microvascular, which is not reflected by an ABI. The best option is to combine several vascular tests to achieve an accurate lower extremity arterial exam.

Toe pressure

Toe pressures and toe brachial pressure index (TBI) have proven to be an accurate option for the diagnosis of PAD in patients at risk for falsely elevated ABI values. The digital vessels are usually not affected by calcifications. The procedure is similar to an ABI, but requires small cuffs and probes as well as a more sensitive technique. Perimed equipment uses laser Doppler for detection and includes a unique local heating feature, assuring reliable results.5

Transcutaneous oxygen (tcpO2 / TCOM)

Transcutaneous oxygen (tcpO2/TCOM) measures the local Oxygen released from the skin through the capillaries, reflecting the metabolic state of the lower limb. It is particularly useful for wound healing prediction, amputation level determination and qualification for hyperbaric oxygen therapy. Transcutaneous oximetry is also recommended as a mean to quantify the severity of ischemia and to stratify the prognosis in CLI patients as well as being useful to diagnose PAD in patients with calcified arteries and loss of toes.

Watch Dr Fife discussing the clinical uses of tcpO2 in the video.

Pulse volume recording

Pulse Volume Recording (PVR) may be used to localize significant occlusive lesions in limbs and is often combined with segmental pressures. PVR is based on air plethysmography and measures changes in pressure, reflecting the arterial pulsatility. Arterial calcifications do not impact on the evaluation of the results, as for ABI measurements.

Segmental pressures

Segmental pressures are similar to toe and ankle pressures, with the addition of two or three blood pressure cuffs positioned on the upper and lower thigh and the upper calf. Segmental pressures can provide an initial indication of the anatomical location of arterial occlusive lesions. They may be falsely elevated in patients with calcified arteries and are therefore often combined with segmental Pulse Volume Recordings (PVR).

Skin perfusion pressure

Skin Perfusion Pressure (SPP) reflects the local pressure in the microcirculation. It has been successfully employed for amputation level determination, in particular major amputations. The measurement procedure is similar to an ankle pressure, with the difference that the probe detecting the return of flow is positioned underneath the pressure cuff.

Heat-controlled laser Doppler

Heat combined with laser Doppler can be used to determine the viability of tissue and the degree of microcirculatory impairment. The increase in blood perfusion as a response to local heating indicates tissue reserve capacity and endothelial function. These are important parameters for predicting healing and determining amputation level.


  1. International Consensus on the Diabetic Foot and Practical Guidelines on the Management and Prevention of the Diabetic Foot, International Working Group on the Diabetic Foot, 2012
  2. European Society for Vascular Surgery, CLI Guideline Committee Guidelines for Critical Limb Ischaemia and Diabetic Foot, 2011
  3. Inter-Society Consensus for the Management of Peripheral Arterial Disease (TASCII). Eur J Vasc and Endovasc Surgery, Vol 33 suppl 1, 2007
  4. Transcutaneous Oximetry in Clincal Pratice: Consensus statements from an expert panel based on evidence. Fife, Smart, Sheffield, Hopf, Hawkins and Clarke. UHM 2009, Vol. 36, No. 1.
  5. The Usefulness of a laser Doppler in the measurement of toe blood pressures. Graaf et al J Vascular Surg, 2000, 32, 1172-1179
  6. Wound Care Practice. Edited by P.J Sheffi eld et al, Best Publishing Company, 2004, p117-156
  7. Kellogg DL, Jr. In vivo mechanisms of cutaneous vasodilation and vasoconstriction in humans during thermoregulatory challenges. J Appl Physiol, 2006, 100, 1709-1718
  8. The correlation between three methods of skin perfusion pressure measurement: Radionuclide washout, laser Doppler flow, and photoplethysmography.Trivino et al. J Vasc Surg, 1992, 15, 823-30

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Improving quality of life since 1981

Perimed AB, established in 1981, provides instruments, software and expertise to enable assessment of the microcirculation. We utilize laser Doppler, laser speckle (LASCA) and transcutaneous oxygen (tcpO2 or TCOM), to accurately monitor and quantify blood perfusion and tissue oxygenation in real-time. Our modular PeriFlux System 5000 and PeriFlux 6000, the latest generation of our PeriFlux System, are excellent choices for diagnosing Peripheral Arterial Disease (PAD) and Critical Limb Ischemia (CLI) or for assessing wound healing potential in your vascular patients. Our blood perfusion imager PeriCam PSI System allows you to investigate spatial distribution, for example during cortical spreading depression.