Vascular Doppler Test 1 Flashcards
What are the different modes to combine together?
2D
gray scale
B-mode
plus:
color doppler
pulsed doppler - spectral doppler
What is duplex imaging?
integrating different forms of Doppler
What is flow analysis?
is there flow?
the presence or absence of flow
how do you determine Portal vein?
echogenic wall
traverses across the liver - hepatic veins go up into the liver
What is important about the doppler curser?
called the gate or sample volume
proper placement is important
in the center of the vessel
How do you tell the direction of flow?
color map
above the black line = toward the transducer red
below black line = away from the transducer blue
what does hepatopetal mean?
toward the liver
this is the way you want to the blood to flow
what does hepatofugal mean?
away from the liver
this is the wrong way for the blood to flow
What is spectral display low flow?
Non resistive - low
high diastolic
constant perfusion
what is spectral display high flow?
Resistive - high
little diastolic or reversed flow
What is spectral display?
time (on the x axis)
Doppler shift frequency is on the vertical y - axis
gray scale quanitity of blood (z)
What is the computer computing with spectral display?
Doppler frequency shift measured in Hz
the machine changes it to speed
what is the pulsatility index (PI)?
a measure of the variability of blood velocity in a vessel, equal to the difference between the peak systolic and minimum diastolic velocities divided by the mean velocity during the cardiac cycle.
What is plug flow?
pattern of blood flow, typically seen in large arteries, in which most cells are moving at the same velocity across the entire diameter of the vessel
What is turbulent laminar flow?
Abnormal
chaotic patterns
What are some techniques for using Doppler?
fasting
suspend respirations
parallel to flow 0 degrees
angle less than 60 degrees
What changes about the SMA after you eat concerning Doppler?
high resistance before
low resistance after
see slides for visual
What is RAS?
renal artery stenosis
what is tardis parvis?
when you lose the point on the doppler wave
Where would you find non resistive low flow confirmed by spectral display?
internal carotid,
hepatic
renal
Where do you find resistive high flow confirmed by spectral doppler?
supply to organs that do not need constant blood supply
external carotid
iliac
brachial arteries
How is blood velocity calculated?
by frequency shifts
How do you read a spectral display?
The peak is the systolic and the end is the diastolic
What is the formula for the resistive index?
RI = Peak systolic velocity - lowest diastolic velocity/ peak systolic velocity
RI = S-D/S
What is resistive index?
peak systole is compared with minimum diastole to quantify a vessels impedance
What picture does typical plug flow give you on the spectral doppler?
a “clear window” under systole
What needs to be present for the volume of blood flow to be calculated?
plug flow must be present
What is parabolic flow?
velocity higher in the center of the laminar layers and decreases at the vessel wall
What are the doppler flow patterns for the Aorta?
High systolic peak
varies at different levels
becomes triphasic closer to the legs
What does triphasic mean?
having or occurring in three phases…seen and heard
What is the Doppler flow pattern of the celiac axis?
Some spectral broadening
no change related to meals