202 Chapter 8: References
References
Pressure Gradient (PGr) in mmHG
Oh, J.K., J.B. Seward, A.J. Tajik. The Echo Manual. 2nd ed., Lippincott, Williams, and Wilkins, (1999),
64.
4 * (Velocity)
2
Peak E Pressure Gradient (E PG)
EPG = 4 * PE
2
Peak A Pressure Gradient (A PG)
A PG = 4 * PA2
Peak Pressure Gradient (PGmax)
PGmax = 4 * PV2
Mean Pressure Gradient (PGmean)
PGmean = 4 * Vmax
2
Pulsatility Index (PI)
Kurtz, A.B., W.D. Middleton. Ultrasound-the Requisites. Mosby Year Book, Inc., (1996), 469.
PI = (PSV – EDV)/V
where PSV = peak systolic velocity
EDV = end diastolic velocity
V = mean flow velocity throughout the entire cardiac cycle
Resistive Index (RI)
Kurtz, A.B., W.D. Middleton. Ultrasound-the Requisites. Mosby Year Book, Inc., (1996), 467.
RI = abs ((Velocity A – Velocity B)/Velocity A) in measurements
where A = velocity cursor +
B = velocity cursor x
Time Averaged Mean (TAM) in cm/s
TAM = mean (mean Trace)
Volume (Vol)
Beyer, W.H. Standard Mathematical Tables, 28th ed., CRC Press, Boca Raton, FL, (1987), 131.
Volume Flow (VF) in l/m
Allan, Paul L. et al. Clinical Doppler Ultrasound, 4th ed., Harcourt Publishers Limited. (2000), 36-38.
VF = CSA * TAM * .06
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