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Flashcards in chapter 4: doppler waveform analysis Deck (40)
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1

capabilities of doppler

confirm diagnosis and location of arterial disease
indicate severity of occlusive process

2

limitations of doppler

waveforms can be effected by temperature
uncompensated CHF can dampen waveforms
unable to discriminate stenosis from occlusion
technically dependent

3

patient positioning

supine with extremities at same level as heart
hip externally rotated
knee slightly bent

4

doppler shift

when a wave is reflected from a moving target the frequency of the wave returning is different from the transmitted wave

5

doppler effect occurs with

relative motion between the source and the receiver of the sound

6

in the doppler shift what is the moving target

blood

7

in the doppler shift what is stationary source

transducer

8

types of doppler velocietry

analog
spectral analysis

9

analog

employs a zero crossing frequency meter
displays the signals graphically on a strip chart recorded

10

analog paper speed

25mm/sec

11

zero crossing frequency meter

counts each time the input signal crosses through zero (baseline) within a time span
high frequency waves has many oscillations
low frequency waves have few
machine estimates frequencies and displays them

12

analog dopller velocimetry drawbakcs

noise
less sensitivity
high velocities are underestimated
low velocities over estimated

13

spectral analysis

individual frequencies are displayed by Fast Fourier Transform FFT method

14

spectral analysis is most commonly used

during duplex evaluation

15

spectral analysis display

time on the X (horizontal) axis and frequency shifts on the Y axis (vertical axis)

16

upper extremity doppler is performed on which arteries

subclavian
axiallary
brachial (at elbow)
radial (thumb side at wrist)
ulnar (5th finger side at wrist)

17

Lower extremity doppler is performed on which arteries

CFA
SFA
popliteal
PTA (medial malleolus)
DPA (top of foot)
Peroneal (lateral malleolus)

18

potential sources of error

improper probe position
probe motion
incorrect angle of incidence
inadequate amount of gel
excessive pressure on the probe
insufficient period of rest before testing

19

a complete arterial exam includes

audible and wave form qualities as well as doppler segmental pressures

20

Normal signals:

triphasic waveform

21

triphasic waveform characteristics

rapid upslope
sharp peak
rapid downstroke
flow reversal
resumption of forward flow

22

examples of triphasic waveforms

UE and LE arteries

23

Abnormal signals

biphasic and monophasic waveforms

24

biphasic waveform characteristics

rapid upslope
sharp peak
fairly rapid downstroke
flow reversal
no resumption of forward flow
can be considered normal in some patients

25

monophasic waveform characteristics

slow upslope
rounded peak
slow down stroke
no reversal

26

a monophasic waveform is often obtained where

proximal to an obstrcution

27

well collateral occlusions can appear similar to

flow distal to a stenosis

28

distal to a stenosis waveforms may appear

monophasic and steady
because of vasodilation of distal vessels due to proximal obstruction

29

subclavian artery signal

high resistance
multiphasic flow

30

proximal occlusion in subclavian artery wil make the signal

more monophasic