Abstract
Perfusion index (PI) and pleth variability index (PVI) have recently been developed as monitoring parameters that can be recorded by a pulse oximeter, Radical-7TM (Masimo Corp., USA). PI is the ratio of pulsatile components to non-pulsatile components of the arterial blood flow derived from pulse oximetry, which shows the perfusion state of the finger to which a pulse oximeter is attached. PVI is a novel algorithm that allows automated and continuous calculation of respiratory variations in the pulse oximeter waveform amplitude. PVI has been reported to have the potential to predict intraoperative fluid responsiveness. Because the normal values for PI or PVI are not known, their relative changes in clinical use need to be noted. Although PI and PVI are largely influenced by the position of the probe, pain, or respiratory state, they are non-invasive and may contribute to optimization of intraoperative fluid therapy. For appropriate interpretation of PI and PVI, combined use of Radical-7TM and other monitors is important.
