PVI®Pleth Variability Index

Pleth Variability Index is an automatic measure of the dynamic change in PI that occurs during the respiratory cycle


  • > PVI® is a measure of the dynamic changes in the Perfusion Index (PI) that occur during one or more complete respiratory cycles.
  • > PI reflects the amplitude of the pulse oximeter waveform and is calculated as the pulsatile infrared signal (AC or variable component), indexed against the non-pulsatile infrared signal (DC or constant component). PI is expressed as a percentage
  • > The calculation for PVI® is accomplished by measuring changes in PI over a time interval where one or more complete respiratory cycles have occurred.
  • > PVI® automatically and continuously calculates the respiratory variations in the plethysmographic waveform.
  • > PVI® may show changes that reflect physiologic factors such as vascular tone, circulating blood volume, and intrathoracic pressure excursions.

PVI® Calculation: How It Works

Caution: Federal (USA) law restricts this device to sale by or on the order of a physician. See instructions for use for full prescribing information, including indications, contraindications, warnings, and precautions.