CW Doppler and Duplex Scanning

CW Doppler capabilities

evaluate for obstruction and venous incompetence

CW Doppler limitations

fixed sample volume, no anatomic image, no range resolution, difficult to differentiate deep venous obstruction vs extrinsic compression

CW Doppler physics principles

2 crystals, 5 Mhz, 45-60 degree angles

looking for CW Doppler signal

find the arterial signal and angle medially

reverse trendelenburg

position where pt legs are below the heart level

spontaneous flow should be present in the extremities without augmentation, except for

tibials, GSV, radial/ulnar

continuous flow patterns in extremities can be consistent with

proximal venous obstruction or shallow respirations

absence of augmentation with distal compression indicates _______, if venous reflux occurs, this indicates ______

obstruction, incompetent valves

venous reflux

a condition where blood flows backward in the veins, instead of upwards towards the heart

with prox compression or _____, venous flow should ____

valsalva, halt

if augmentation happens with valsalva/______, this indicates _____

prox compression, venous reflux

once prox compressions are______, signal should _____. If not, this indicates obstuction

released, augment

causes pulsatile flow in subclavian vein

proximity to heart

can cause pulsatile flow in the lower extremities

fluid overload, chronic venous insufficiency, or increased venous pressure

can result in increased venous pressure

a heart problem, like CHF

venous flow is related to _____ and can also be affected by _____

arterial peripheral resistance, venomotor tone

vasodilation of veins flow

continuous flow with less respiratory variations

vasocontriction of veins flow

decreased venous flow signals

false positive causes

extrinsic compression, peripheral arterial disease, improper doppler angle or probe pressure

peripheral arterial disease leads to

decreased venous filling

COPD leads to an elevated _____ which alters pressure gradients and reduces _____

central nervous venous pressure, venous flow patterns

CW Doppler false negative causes

partial thrombosis, collateral development, duplicate deep veins

Duplex false negative causes

technically limited, prox obstruction (iliacs)

Duplex scanning limitations

edema, recent surgery, obesity

duplex scanning abd/pelvic capabilities

portal hypertension, venous thrombus, extrinsic vs intrinsic, assess shunts, eval liver disease

automatic cuff inflator for FV eval

cuff at thigh, 80 mmHg

automatic cuff inflator for pop eval

cuff at calf, 100 mmHg

automatic cuff inflator for PTV eval

cuff at transmetatarsal, 120 mmHg

<0.5 s

normal flow reversal

0.5-1.0 s

abnormal flow reversal

color flow imaging reveals venous reflux as a _____ during ____

directional shift, valsalva

subclavian and innominate are difficult to ______, and along with IJV have _____ waveforms

compress, pulsatile

dilated IVC size

>2 cm

can cause dilated IVC and pulsatile MPV

cardiac failure, and fluid overload

acute thrombus

not fully compressible, low-level echoes, dilated vein, rouleau formation

if flow is not spontaneous at CFV, FV, or POP V

obstruction distal to or at site

continuous flow instead of phasic in CFV, FV, and POP V

prox obstruction

no augment with distal comp at CFV, FV, and POP V

obstruction between imaging and comp or slightly more prox

no augment with prox release in CFV, FV, POP V

prox obstruction

forms subclavian vein

cephalic and axillary

forms the innominate vein

subclavian and IJV

forms the axillary vein

basilic and brachial

forms brachial vein

radial and ulnar

thrombus _____ over time and leaves a ____ wall

retracts, thickened

miscellaneous findings

edema, lymph node, muscle tear, nerve, sarcoma, venous aneuryysm

budd chiari

results from hepatic vein occlusion and presents with hepatomegaly, abdominal pain, and ascites onset

perforator vein incompetence

more often associated with reflux in the superficial veins

perforator size >3.5 mm

reflux present 90% of the time

stasis changes at the ankle

most obviously affected area lies directly above an incompetent perforator

what is being shown in this image?

venous reflux

what is being shown in this image?

normal finding

what is being shown in this image?

proximal obstruction