Doppler Waveform Analysis Flashcards Preview

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Flashcards in Doppler Waveform Analysis Deck (17):
1

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

2

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

3

Patient positioning?

Supine with the extremities at the same level as the heart. Decreases influence of hydrostatic pressure. Patients hip is externally rotated, knee slightly bent.

4

Employs a zero crossing frequency meter, to display the signals graphically on a strip chart recorder?

Analog
paper speed=25 mm/sec

5

Drawbacks of analog?

noise, less sensitivity, high velocities are underestimated, low velocities are overestimated.

6

Individual frequencies displayed by Fast Fourier Transform (FFT) method?

Spectral analysis

7

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

8

Frequency of transducer used?

8-10 MHz

9

UE locations of the Doppler velocity wave forms recorded?

Subclavian, axillary, brachial at antecubital fossa, radial, ulnar

10

LE locations of the Doppler velocity wave forms recorded?

common femoral, superficial femoral, popliteal, PT, DPA, peroneal

11

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.

12

A monophasic/dampened (pulsatile) signal is often obtained where in relation to an obstruction?

proximal

13

Vasodilatation of the ______ vessels often occur with _____ obstruction, reducing pulsatility; causing the signals to have lower resistant (steady) flow quality.

distal, proximal

14

Analog Doppler signals may suggest occlusion or a pre-occlusive vessel (string sign). Analog Doppler not capable of portraying velocities of less than what?

6 cm/sec

15

How is pulsatility index calculated?

By dividing the peak-to-peak frequency difference (P1-P2) by the average frequency.

16

Acceleration time helps to differentiate what?

inflow (aorto-iliac) disease from outflow (S-femoral) disease

17

An acceleration time of what suggests presence of proximal iliac disease.

> 133 msec