Flashcards in Doppler Waveform Analysis Deck (17)
Capabilities of Doppler waveform analysis?
a. Help confirm diagnosis/approx location of arterial occlusive disease.
b. Indicate severity of the occlusive process.
c. Combined with Doppler segmental pressures
Limitations of Doppler waveforms analysis?
a. Casts or extensive bandages
b. Waveforms may be affected by ambient temp.
c. Congestive heart failure may result in dampened waveforms.
d. Unable to discriminate stenosis from occlusion
e. Technically dependent test
Supine with the extremities at the same level as the heart. Decreases influence of hydrostatic pressure. Patients hip is externally rotated, knee slightly bent.
Employs a zero crossing frequency meter, to display the signals graphically on a strip chart recorder?
paper speed=25 mm/sec
Drawbacks of analog?
noise, less sensitivity, high velocities are underestimated, low velocities are overestimated.
Individual frequencies displayed by Fast Fourier Transform (FFT) method?
Characteristics of spectral analysis?
a. More commonly used during duplex evaluation
b. Time displayed on the horizontal axis (x); frequency shifts displayed on the vertical axis (y)
c. Free of many of the analog recording drawbacks
Frequency of transducer used?
UE locations of the Doppler velocity wave forms recorded?
Subclavian, axillary, brachial at antecubital fossa, radial, ulnar
LE locations of the Doppler velocity wave forms recorded?
common femoral, superficial femoral, popliteal, PT, DPA, peroneal
Potential sources of technical error?
Improper probe position.
Inadvertent probe motion.
Incorrect angle of incidence (45-60 to skin)
Inadequate gel amount.
Excessive pressure on probe tip.
Insufficient period of rest before testing.
A monophasic/dampened (pulsatile) signal is often obtained where in relation to an obstruction?
Vasodilatation of the ______ vessels often occur with _____ obstruction, reducing pulsatility; causing the signals to have lower resistant (steady) flow quality.
Analog Doppler signals may suggest occlusion or a pre-occlusive vessel (string sign). Analog Doppler not capable of portraying velocities of less than what?
How is pulsatility index calculated?
By dividing the peak-to-peak frequency difference (P1-P2) by the average frequency.
Acceleration time helps to differentiate what?
inflow (aorto-iliac) disease from outflow (S-femoral) disease