What is Perfusion Index (PI)?
Perfusion Index (PI) is the ratio of the pulsatile blood flow to the non-pulsatile static blood flow. It indicates the pulse strength at the sensor site. Higher perfusion rate= more blood flow, lower perfusion rate = less blood flow.
Ranges from 0.02% to 20%.
0.02% = very weak pulse
20% = an extremely strong pulse
Did you know there are no specific normal PI values?
Every individual must establish their own normal/baseline values. Monitor in the morning versus after exercise. Write down any changes in PI if you feel different when PI is lower than usual.
Why is PI value important?
Acts as a good indicator of the reliability of the pulse oximeter reading.
Provides instant perfusion status of the selected monitoring site.
Optimal monitoring sites are chosen with a relatively high, stable PI.
Fun facts about PI values
The sensitivity of oximeter is determined by the PI value it is able to detect.
The lower the PI value, the more reliable is the oximeter.
For most pulse oximeters, the PI readings are above 0.6% or even unavailable.
Good oximeters which are designed to detect extremely low PI (0.2-0.3%) would be more costly.
Prepared by: Chew Ee Wei, a HTM Pharmacist.
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