Non-invasive physiologic studies require separate and distinct equipment from the Duplex ultrasound scanner. Instrumentation must allow the display and permanent recording of pressures with bi-directional Doppler analysis of blood flow, plethysmography and/or oxygen tension measurements.

• Continuous wave (CW) Doppler must provide:
  • Doppler frequencies appropriate for vessels examined
    • Typically range from 4 to 10MHz
  • Direction sensitive Doppler blood flow meter
  • Doppler waveform display with bi-directional flow capabilities
  • Audible output and permanent recording of Doppler waveforms
• Segmental limb plethysmography must provide:
  • Equipment capable of measuring small segmental volume changes and making permanent recordings of blood pressure measurements
  • Blood pressure cuffs of various sizes for each limb segment and digit evaluated
    • The recommended size is 20% wider than the limb diameter
• Pulse volume plethysmography (PVR) must provide:
  • Equipment capable of measuring small limb volume changes and saving permanent PVR waveforms
  • Capability to be calibrated before each exam
  • Blood pressure cuffs of various sizes for each limb segment and digit evaluated
• Photoplethysmography (PPG) must provide:
  • Electrical sensor for signal display
  • Capable of providing a permanent recording of PPG waveforms