Peripheral Perfusion Index

The Peripheral Perfusion index (PI) is the ratio of the pulsatile blood flow to the non-pulsatile or static blood in peripheral tissue. Perfusion Index thus represents a non-invasive measure of peripheral perfusion that can be continuously and noninvasively obtained from a pulse oximeter. A site with high pulse amplitude (high PI number) generally indicates an optimal monitoring site for other pulse oximetry and Pulse CO-Oximetry measures. The fingertip is the standard monitoring site for pulse oximetry. The difference between the rate of oxygenated haemoglobin and reduced haemoglobin as arterial oxygen saturation is measured by the amount of light absorbed by the tissue when light is transmitted through the finger. The PI is useful for quickly

Oxyhaemoglobin (HbO2) Absorbs visible and infrared (IR) light Differently than deoxyhaemoglobin (Hb), and appears bright red as opposed to the darker brown Hb. Absorption in the arterial blood is represented by an AC signal which is superimposed on a DC signal representing absorptions in other substances like pigmentation in tissue, venous, capillary, bone, and so forth. Cardiac-synchronized AC signal is approximately 1% of the DC level.

Perfusion Index (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 (0.02-20%).

The main objective of this project is to track the Perfusion index of critically ill patients, which helps in giving more information about the patient’s health data in a more convenient way. We used a Pulse Oximeter sensor and obtained the IR LED values and RED LED values separately and used those values to find the PI Index value. Changes in PI can also occur as a result of local vasoconstriction (decrease in PI) or vasodilatation (increase in PI) in the skin at the monitoring site. These changes occur with changes in the volume of oxygenated blood flow in the skin microvasculature. The measurement of PI is independent of other physiological variables

Detection of a spike in PI is a sign to the physician of the successful onset of anaesthesia. Conversely, no increase in PI in a patient given anaesthesia may be an early warning of anaesthetic failure. Most anaesthetics produce a vasodilatative effect by way of increasing the vasodilatation threshold and decreasing the vasoconstriction threshold. Anesthesia can also cause temperature redistribution, which further increases peripheral perfusion. PI value has been considered a useful tool for accurately monitoring changes in peripheral perfusion in real time caused by certain anesthetics. An increased PI is an early indicator of the pharmacologic effect of the anesthesia, often occurring before the onset of the anesthetic effect providing the physician an early indicator of successful anesthetic administration. In the neonatal acute care setting, a low PI has been shown to be an objective indicator of severe illness. In conjunction with oxygen saturation and pulse rate, a diminished PI becomes an important indicator of a critical state of neonatal health. As such, the PI may be important to consider as a standardized, objective measure in addition to conventional subjective means of assessing the state of the neonate. From