1. Vascular Technology Lecture 27: Venous Continuous-Wave Doppler HHHoldorf

2. Continuous – Wave Doppler
Capabilities
Evaluation of deep venous obstruction
Evaluate venous incompetence

3. Limitations
Unable to differentiate abnormal flow patterns from DVT versus extrinsic compression, i. e., tumor, ascites, pregnancy
Normal flow patterns may be evident with partial or well-collateralized thrombosis
Paired deep veins in calf limit diagnosis of an isolated calf clot

4. Sources of FALSE POSITIVE studies include:
Extrinsic compression: tight clothing, tumors, ascites, pregnancy, obesity, improper patient positioning, or pain causing muscle contraction
Peripheral arterial disease (PAD): decreased venous filling
Chronic obstructive pulmonary disease (COPD)
Improper Doppler angle or probe pressure

5. Sources of FALSE NEGATIVE studies include:
Collateral development
Presence of bifed system (multiple deep veins)
Last limitation:
Test requires a very experienced Technologists

6. Patient Positioning Supine with body shifted to side being examined
Leg externally rotated with hip and knee flexed
An extreme side-lying position may diminish extrinsic compression on IVC from Pregnancy, ascites, or tumor formation.

7. Patient Positioning continued…
Position should facilitate venous filling (extremities lower than heart) i.e., reversed Trendelenburg (approximately 30 degrees.

8. Physical Principles The Doppler effect REMINDERS
Use 5 MHz probe held at 45 – 60 degree angle to skin surface
Deep Veins found adjacent to corresponding artery
Correct vessel identification requires hearing accompanying arterial signal
Examination based on audible venous signals

9. Technique Begin with asymptomatic side
Placing probe at inguinal ligament, identify common femoral artery: angle probe medially to insonate common femoral vein (CFV) and evaluate venous Doppler signals

10. Venous Flow Patters Spontaneous * Phasic +*
Augment with distal compression
Augment with proximal release
* The tibial veins may normally NOT have these qualities

11. CFV on symptomatic side evaluated for same flow patterns
The femoral, popliteal, and posterior tibial veins are evaluated going from asymptomatic side to symptomatic side
Abnormal venous signals require repositioning and re-evaluation before a conclusion can be reached

12. Homework Textbook SDMS Assignments Chapter 29: Continuous-Wave Doppler
Pages 301 – 306
SDMS Assignments