Calculate Doppler pulsatility index from peak, end-diastolic, and mean velocity, reverse-solve any velocity, and compare RI, S/D ratio, and waveform spread.
Pulsatility Index Formula
The following formula is used to calculate the Pulsatility Index (PI) in a Pulsatility Index Calculator:
Variables:
- PI is the Pulsatility Index
- Systolic Velocity is the maximum velocity of blood flow during systole
- Diastolic Velocity is the minimum velocity of blood flow during diastole
- Mean Velocity is the average velocity of blood flow over a cardiac cycle
To calculate the Pulsatility Index, subtract the Diastolic Velocity from the Systolic Velocity, and then divide the result by the Mean Velocity.
What is a Pulsatility Index?
The Pulsatility Index (PI) describes the spread between peak systolic and end-diastolic velocity relative to the measured time-averaged velocity in a specific Doppler waveform. PI varies with the vessel, organ, physiology, patient condition, and acquisition method. A higher or lower value is not, by itself, evidence of stenosis, vascular disease, fetal distress, or another diagnosis; interpretation requires the application-specific protocol and the original waveform context.
How to Calculate Pulsatility Index?
The following steps outline how to calculate the Pulsatility Index:
- First, determine the systolic velocity (SV) in cm/s.
- Next, determine the diastolic velocity (DV) in cm/s.
- Next, determine the mean velocity (MV) in cm/s.
- Use the formula PI = (SV - DV) / MV to calculate the Pulsatility Index.
- Finally, calculate the Pulsatility Index using the given values.
Example Problem:
Use the following variables as an example problem to test your knowledge:
Systolic velocity (SV) = 120 cm/s
Diastolic velocity (DV) = 80 cm/s
Mean velocity (MV) = 100 cm/s
