Vascular Technology Lecture 27: Venous Continuous-Wave Doppler HHHoldorf

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

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

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

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

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.

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

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

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

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

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

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