Doppler Waveform Analysis Flashcards
What is the purpose of a Doppler waveform analysis
Help confirm diagnosis/ APPROXIMATE location and SEVERITY of arterial occlusive disease
A downfall with Doppler waveform analysis is that we cannot discriminate _____ from an occlusion
A stenosis
What position does the patient need to be in for a Doppler analysis and why
Supine, to keep extremities at the same level as the heart decreasing influence from hydrostatic pressure
Along with the patient being supine for Doppler tests, what other positions should be considered
Knees slightly bent to help externally rotate the hips
Prone
RLD/LLD
Which physical principle relates to the waveform being reflected from a MOVING TARGET (blood), the frequency of that wave RECEIVED is different from the TRANSMITTED wave
The Doppler effect
Explain the Doppler shift
FREQUENCY of the wave RECEIVED is different from the TRANSMITTED wave
Two piezoelectric crystals: one constantly sending ultrasound, one constantly receiving reflected waves
This describes what?
Continuous wave Doppler (CW)
With CW Doppler, the reflected frequency is higher or lower than the transmitted frequency depending on _____
Direction of flow
This type of Doppler velocimetry employs a ZERO CROSSING frequency meter displaying the signals on a strip chart recorder
Analog
Which frequency (high or low) has more oscillations
HIGH frequency has MANY
LOW frequency has only a FEW
T/F
Analog (zero crossing frequency meter) ESTIMATES the frequency that is displayed on screen?
True
But has acceptable accuracy
What are two drawbacks for analog (zero crossing frequency meter)
Noise
Less sensitive
This type of Doppler velocimetry uses individual frequency a displayed by FAST FOURIER TRANSFORM (FFT) method
Spectral analysis
Is analog Doppler velocimetry more commonly used for duplex evaluation or is spectral analysis?
Spectral analysis
Related to spectral analysis:
The horizontal axis (X) displays _____
The vertical axis (Y) displays ______
Time/frequency shift
X axis = time
Y axis = frequency shift
What MHz probe range is recommended for Doppler analysis
8-10 MHz
Which upper extremity velocities are recorded
Subclavian Axillary Brachial (@antecubital fossa) Radial Ulnar
Which lower extremity velocities are recorded
Common femoral (CFA)
Superficial Femoral (SFA)
Popliteal
Posterior tibial (PTA) / medial malleolus
Dorsalis pedis (DPA)
Peroneal / lateral malleolus (if necessary)
The AUDIBLE and WAVE FORM qualities are observed , documented and combined with what Doppler technicque
Doppler segmental pressures
Potential sources of technical error with Doppler analysis include
(5)
Incorrect probe position Incorrect angle of incidence Inadequate amount of gel Excessive pressure on the probe tip Insufficient period of rest before testing
Describe a normal triphasic signal: upper and lower extremities
(5)
Rapid upstroke Sharp peak Rapid downstroke Flow reversal Resumption of foward flow
Describe an ABNORMAL biphasic signal (5)
Biphasic can be considered normal in some patients
Rapid upslope Sharp peak fairly rapid down stroke Flow reversal No resumption of foward flow
Describe the ABNORMAL monophasic signal (4)
Slow upslope
Rounded peak
Slow downstroke
No reversal
A monophasic/pulsatile signal is often obtained _______ to a stenosis
Proximal
**distal or well collateralized occlusions may also be monophasic but less pulsatile
Vaso__________ of the ______ vessels often occur with proximal obstruction, reducing the PULSATILITY.
This makes the signal have lower resistance (steady)flow quality
VasoDILATATION of the DISTAL
Describe two charectoristics of arterial flow in the subclavian
High resistant
Multiphasic flow
A ______ occlusion or critical stenosis will cause the subclavian artery to become monophasic
Proximal
T/F
Waveforms found in the hand can be quite variable
TRUE
With a relaxed and warm patient, the brach,radial, and ulnar arteries have what kind of resistance
Lower resistance
Analog Doppler is not capable of portraying velocities less than_____ cm/sec
Less than 6 cm/sec
What is the “string sign” during a Doppler analysis
When there is an absent Doppler signal
- this is suggestive of occlusion or pre-occlusion vessels
The disease when blood is flowing into the lower extremities is called ________, however, the blood that is going out into the extremities is call ______
INFLOW: blood flowing into lower extremities… EX= aorta-iliac disease
OUTFLOW: blood flowing out into lower extremities…. EX= femoral-popliteal disease
Inflow—> CFA —-> outflow
By dividing the peak-to-peak frequency difference (P1 - P2) by the mean (average) frequency we will get the ________ index.
Pulsatility index (PI)
What would proximal arterial obstruction to do the acceleration time on Doppler waveform
Would cause a slowing of the time interval between the onset of systole to the point of maximum peak
What does an acceleration time of greater than 133 m/sec suggest?
That would suggest a proximal arterial disease
Rounded peak on waveform
