Doppler Waveform Analysis

Question 1

Capabilities of Doppler waveform analysis?

Answer 1

a. Help confirm diagnosis/approx location of arterial occlusive disease.
b. Indicate severity of the occlusive process.
c. Combined with Doppler segmental pressures

Question 2

Limitations of Doppler waveforms analysis?

Answer 2

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

Question 3

Patient positioning?

Answer 3

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

Question 4

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

Answer 4

Analog

paper speed=25 mm/sec

Question 5

Drawbacks of analog?

Answer 5

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

Question 6

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

Answer 6

Spectral analysis

Question 7

Characteristics of spectral analysis?

Answer 7

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

Question 8

Frequency of transducer used?

Answer 8

8-10 MHz

Question 9

UE locations of the Doppler velocity wave forms recorded?

Answer 9

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

Question 10

LE locations of the Doppler velocity wave forms recorded?

Answer 10

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

Question 11

Potential sources of technical error?

Answer 11

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.

Question 12

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

Answer 12

proximal

Question 13

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

Answer 13

distal, proximal

Question 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?

Answer 14

6 cm/sec

Question 15

How is pulsatility index calculated?

Answer 15

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

Question 16

Acceleration time helps to differentiate what?

Answer 16

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

Question 17

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

Answer 17

> 133 msec