GE Medical Systems 500, User Manual, Page: 261 / 636

General Calculations
LOGIQ 500 Basic Users Manual
2276612–100 Rev. 0
8–11

General Calculation Formulas
Calc
Mnemonic Calc Name Input Measurements Formula
MaxPG Maximum Pressure
Gradient two Doppler blood flow peak
velocities MaxPG[mmHg]=4x(v1^2–v2^2)
MeanPG Mean Pressure Gradient flow velocities from one time
marker to another time marker
in a Doppler display MeanPG[mmHg]=
n
4x
ȍ
(Vi^2)/n
i=1
SV Stroke Volume flow velocities from one time
marker to another time marker
in a Doppler display and one
area SV[ml]= (sum{V
t^2
} from t1 to
t2)x a1
CO Cardiac Output two distances and one 2 beat
time interval CO[1/min]=
SVxHR/1000
FV Flow Volume flow velocities from one time
marker to another time marker
in a Doppler display and one
area FV [ml] = (sum{Vt[m/s]} from
t1 to t2) x a1[cm^2]
FVO Flow Volume Output flow velocities from one time
marker to another time marker
in a Doppler display and one
area FVO [ml/min] = FV [ml] /
(t2–t1) x 60000
% Stenosis Stenosis Ratio two areas (by ellipse, trace,
circle or distance) % Stenosis= [1–(A
residual
/
A
lumen
)]x100
PI Pulsatility Index two Doppler blood flow peak
velocities and TAMAX PI=(V
max
–V
diastole
)/TAMAX
*NOTE*
RI Resistivity Index two Doppler blood flow peak
velocities RI=(V
max
–V
diastole
)/V
max
*NOTE*
HR Heart Rate (beats/minute) one 2 beat time interval HR[BPM]=120[sec]/
2beat time [sec]
A/B Ratio Velocities Ratio two Doppler blood flow peak
velocities A/B=V
1
/V
2
TAMAX Time Averaged Maximum
Velocity (Trace Method is
Peak or manual) two time marks in a Doppler
display TAMAX=sum{V
t
} from t1 to
t2/(t2–t1) [cm/s or m/s]
TAMIN Time Averaged Minimum
Velocity (Trace method is
Floor) two time marks in a Doppler
display TAMIN=sum{V
t
} from t1 to
t2/(t2–t1) [cm/s or m/s]
TAMEAN Time Averaged Mean
Velocity (Trace method is
Mean) two time marks in a Doppler
display TAMEAN=sum{V
t
} from t1 to
t2/(t2–t1) [cm/s or m/s]
TAMODE Time Averaged Mode
Velocity (Trace method is
Mode) two time marks in a Doppler
display TAMODE=sum{V
t
} from t1 to
t2/(t2–t1) [cm/s or m/s]
*NOTE*: V
diastole
= V
min
or V
end–diastole
(depends on preset selection)
Table 8–1. General Calculation Formulas