Although duplex ultrasound imaging is used almost exclusively for the non-invasive diagnosis of peripheral arterial disease (PAD), physiologically-based testing modalities remain prominent for assessing it in the upper extremity. Plethysmography is an ideal modality for recording digit pulse waveforms, which are needed to measure systolic pressures. These are used to record the response of digit waveforms to arm and head maneuvers, for detecting extrinsic arterial compression syndromes in the shoulder girdle, (TOS).

An Allen Test can be modified by employing plethysmographically-derived digit waveforms. These assess the respective contributions of the radial and ulnar arteries to the hand circulation, which provide objective documentation for surgical decisions prior to creating a dialysis fistula or graft. Cold sensitivity is assessed from digit temperature recovery following cold immersion. This can be accomplished directly by measuring digit temperatures (using thermometry) or indirectly from the amplitude and morphology of the digit pulse waveforms.