CH 29: continuous wave doppler

The capabilities of continuous wave doppler includes its ability to evaluate for what 2 pathologies?

• Deep venous system for obstruction

• Venous incompetence

Complete the blanks of the 6 limitations of continuous wave doppler.

1. Fixed _________

2. No ______ resolution

3. No ability to place _____________ at a specific depth

4. No ________ image

5. Abnormal flow patterns can make differentiating patterns of __________________ and _________________ difficult

6. Paired ___________ veins in the calf make the diagnosis of _____________________ extremely difficult

1. Sample size

2. Range

3. Sample volume

4. Anatomic

5. Deep venous obstruction and extrinsic compression

6. Deep, isolated calf vein thrombosis

Because continuous waveforms provide no anatomic imaging, how is the exam interpreted? (2)

• Seeing waveforms

• Hearing the signals

1. What exam is being performed here?

2. What probe is used here?

1. Ankle-Brachial Index

2. Continuous wave probe

Will continuous or pulsed wave dopplers have a more accurate measurement of high velocities?

Continuous wave

Will continuous or pulsed wave dopplers have a poor range resolution?

Continuous wave

Will continuous or pulsed wave dopplers have a good range resolution?

Pulsed wave

Will continuous or pulsed wave dopplers have limitations on maximum velocities?

Pulsed wave

List the 4 reasons for a false-positive study.

• Extrinsic compression

• Peripheral arterial disease

• Chronic obstructive pulmonary disease (COPD)

• Improper doppler angle/Probe pressure

Describe what a false-positive study is.

We said the patient has a disease, but they tested negative for disease

Describe what a false-negative study is.

We said the patient does not have a disease, but they tested positive for disease

List the 4 factors that can cause extrinsic compression.

• Tight clothing

• Tumors

• Ascites

• Pregnancy

Peripheral arterial disease can cause a decrease in what?

Venous filling

1. COPD can result in an elevated…

2. The elevation in this can alter…

3. And can reduce…

1. Central venous pressure

2. Pressure gradients

3. Venous flow patterns

An increase in probe pressure can (1)_________ venous flow and/or result in (2)____________ flow that may be misinterpreted as flow in a (3)_________ vessel.

1. Obliterate

2. Accelerated

3. Diseased

List the 3 reasons for a false-negative study.

• Partial thrombosis

• Collateral development

• Duplicate deep veins

How many piezoelectric crystals does continuous wave doppler have?

2

With the 2 piezoelectric crystals, describe what they’ll each be doing?

• One is continuously sending signals

• The other is continuously receiving signals

1. What probe frequency is used for continuous wave doppler?

2. What angle should the probe be from the skin surface?

1. 5 MHz

2. 45 - 60 degrees

The deep veins are found _________ to the corresponding artery.

Adjacent

Because the deep veins are found adjacent to their corresponding artery, correct vessel identification depends on hearing the accompanying (1)_______ signal and then moving (2)________.

1. Arterial

2. Medial

1. What kind of doppler does this probe perform?

2. What kind of exam is performed with this probe?

3. What kind of frequency will it have?

1. Continuous wave

2. ABI

3. 5 MHz

The patient for a continuous wave doppler should be positioned similar to what other study?

Lower venous duplex

Having the patient in what position helps to facilitate venous filling?

• Extremities lower than the level of the heart

• OR reverse Trendelenburg

When the patient is positioned with their extremities lower than the level of the heart, what can that help facilitate?

Venous filling

Define the reverse Trendelenburg.

When the extremities are lower than the level of the heart

If abnormal venous signals are obtained, what 2 tips are essential to do before reaching a reliable conclusion?

• Repositioning

• Reevaluation

When performing a continuous wave doppler exam, we want to start with what side?

Asymptomatic side

1. With a continuous wave doppler exam, the probe will first be placed in what area?

2. While in this area, what vessel should the sonographer identify?

3. Once this vessel has been identified, where should the probe move to insonate the CFV?

1. Inguinal ligament

2. CFA

3. Medially

1. Once the sonographer has scanned the asymptomatic side, what vessel will the sonographer evaluate on the symptomatic side?

2. What 2 things will the sonographer look for on the symptomatic side?

1. CFV

2. • Same flow patterns

   • Responses to compression maneuvers

On the symptomatic side, aside from the CFV, which 3 other vessels will also be evaluated?

• Femoral veins

• Popliteal veins

• PTVs

What is occurring in the image on the right?

CFV compression

The flow characteristics evaluated with CW doppler are also evaluated when using (1)_____ doppler with (2)_______ scanning.

1. PW

2. Duplex

Define spontaneity.

Spontaneous flow without augmentation

Spontaneity is when the venous signal is clearly heard at all sites, with the exception at what 3 vessels?

• Tibial veins

• GSVs

• Radial/Ulnar veins

1. Vasoconstriction occurs when the veins are… (3)

2. Vasoconstriction will reduce what?

1. • Cold

   • Nervous

   • In pain

2. Venous flow

With vessels that typically show spontaneity, if signals are only becoming evident AFTER performing distal compression, what can that be an indication of?

Abnormal

Define patency.

Spontaneous flow following distal augmentation

Which vessels are considered ‘patent’? (3)

• Tibial veins

• Radial veins

• Ulnar veins

Distal augmentation provides documentation that the vessel is…

Patent

Does this doppler waveform show a vessel that displays spontaneity or patency?

Spontaneity

Does this doppler waveform show a vessel that displays spontaneity or patency?

Patency

Lower extremity venous signals are normally ______ with respiration.

Phasic

1. When is it normal to see a continuous flow pattern of the veins in the upper or lower extremity?

2. It is abnormal to see a continuous flow pattern of the veins in the upper or lower extremity with what pathology?

1. With patients who have shallow breathing

2. Proximal venous obstruction

Define phasicity.

Flow changes with respiration

This is a respiratory flow pattern.

How would this flow type be labeled?

Rapid

This is a respiratory flow pattern.

How would this flow type be labeled?

Slow

This is a respiratory flow pattern.

This flow type can be seen with what medical condition?

Apnea

Seeing this continuous flow pattern in the lower or upper extremities can be an indication for what 2 conditions?

• Normal, shallow respirations

OR

• Proximal venous obstruction

This flow pattern can be described as…

Phasic

Describe what the sonographer does for augmentation with distal compression.

Manual compression is applied distal to the transducer

Distal compression should _______ the venous signal.

Augment

Augment on doppler will show a…

Increase

The absence of augmentation during distal compression is consistent with…

An obstruction

Normally, when the sonographer releases from distal compression, what should venous flow do?

Move forward

After the sonographer releases from a distal compression, reversed doppler signals are seen/heard. What does this finding suggest?

Incompetent valves (reflux)

What has been done for the waveform to appear this way?

Augmentation with distal compression

1. Does this waveform appear normal or abnormal?

2. If abnormal, what about the waveform indicates that?

3. If abnormal, what pathology could this waveform be an indication of?

1. Abnormal

2. Reversed doppler signals

3. Incompetent valves (reflux)

What is abnormal about this waveform? (2)

• Reversed doppler signals

• Does not resume in same direction

Proximal compression can also be done through what maneuver?

Valsalva

With maximal proximal compression, venous flow should be…

Halted

The effect of proximal compression on venous flow is similar to that of what movement?

Valsalva Maneuver

What can be used to substitute for Valsalva Maneuver?

Proximal compression

When performing valsalva or proximal compression, if the waveform augments, is that normal?

No

When performing valsalva or proximal compression, if the waveform halts, is that normal?

Yes

1. A waveform that augments during proximal compression/valsalva is indicative of what pathology?

2. The pathology form question 1 signifies what other pathology?

1. Valvular incompetence

2. Venous reflux

Upon release of proximal compression/valsalva, what should be seen on the venous doppler waveform?

Augmentation

1. What is abnormal to see upon release of proximal compression/valsalva?

2. Seeing this can be indicative for what pathology?

1. No doppler signals

2. Obstruction

What should be seen on the venous doppler waveform during proximal compression/valsalva to indicate a competent vein?

Halted flow

1. What movement is being performed for the waveform to appear this way?

2. Does this show if the vein is competent or incompetent?

1. Proximal compression OR Valsalva maneuver

2. Competent

Define extrinsic compression.

Pressure on the vessels from surrounding tissues nad/or structures

List 3 examples that can cause extrinsic compression.

• Tumors

• Pregnancy

• Ascites

Extrinsic compression can ______ normal flow patterns.

Alter

1. What flow type is commonly and normally heard in the subclavian vein?

2. Why is this?

1. Pulsatile flow

2. Close proximity to the heart

What kind of venous flow is not normal to see in the lower extremities?

Pulsatile

If pulsatile venous flow is evident in the lower extremities, what 3 pathologies can it be indicative of?

• Fluid overload

• Chronic venous insufficiency

• Increased venous pressure

Increased venous pressure is due to what pathology?

CHF (congestive heart failure)

Venous flow is also related to _________________ resistance.

Arterial peripheral

Venous flow can be affected by changes in ___________ tone.

Venomotor

List the 2 areas of venomotor tone.

• Vasodilation

• Vasoconstriction

Vasodilation may result in more (1)__________ flow with less (2)___________ variation.

1. Continuous

2. Respiratory

Will this be vasodilation or vasoconstriction?

“Results in more continuous flow with less respiratory variation.”

Vasodilation

Vasoconstriction occurs from what 4 factors?

• Trauma

• Pain

• Anxiety

• Need to conserve body heat

Vasoconstriction may result in markedly _________ venous flow signals.

Decreased

Will this be vasodilation or vasoconstriction?

“May result in markedly decreased venous flow signals.”

Vasoconstriction

*SCV= Subclavian Vein

1. Is this flow type continuous or pulsatile?

2. Based on the vessel scanned, is this waveform normal or abnormal?

1. Pulsatile

2. Normal