Chapter 29 - Continuous wave doppler

Question 1

Causes of false-positive in continuous wave doppler venous

Answer 1

1) extrinsic compression
2) PAD
3) COPD
4) improper doppler angle

Question 2

Causes of false-negative in continuous wave doppler venous

Answer 2

1) partial thrombosis
2) collateral development
3) presence of bifid system (duplicate veins)

Question 3

Techniques of continuous wave doppler

Answer 3

1) supine
2) shift to side being evaluated and external rotate hip; flex knee slightly
3) Trendelenburg 30 degrees
4) Landmark inguinal ligament, femoral pulse then CFV
5) spontaneous signal with respiration noted
6) ask for deep breath and valsalva (proximal compression of vein)
7) FV, pop, PTV; compress proximal

Question 4

Veins that do not have spontaneity

Answer 4

1) tibial veins
2) GSV
3) radial and ulnar veins

Question 5

Causes of continuous flow patterns of veins (no respiratory phasicity)

Answer 5

1) obstruction

2) shallow respiration

Question 6

Causes of no augmentation with distal compression

Answer 6

obstruction

Question 7

Causes of flow after distal release

Answer 7

reflux

Question 8

Results of proximal compression

Answer 8

Same as valsalva

1) no flow normally
2) augmented flow means reflux
3) release should give flow; no flow means obstruction

Question 9

Causes of pulsatile venous flow

Answer 9

1) normal in subclavian but not in LE
2) fluid overload
3) venous dysfunction
4) increased venous pressure
5) tricuspid valve regurgitation