URR LE Arterial Doppler Eval Flashcards
what are limitations to LE A doppler?
-bandages, casts
-room temp (cold = vasoconstriction, heat=vasodilation)
-heart failure
what happens to flow during decreased cardiac function?
decreased function = decreased flow
what happens to resistance in blood flow during stiff or calcified vessel?
increased resistance
the more muscular a patient what happens to resistance for blood flow?
decreased resistance
where does increased resistance vascular beds occcur?
-extremities, muscles, pre-prandial digestive organs
where does decreased resistance vascular beds occur?
liver, kidney, brain
what will abnormal flow in extrems look like?
-low resistance
-monophasic
-increased antegrade diastolic flow also demonstrated due to inability of systolic flow to satisfy tissue needs
bilat decreased velocities can indicate what?
cardiac issues
changes in waveform phasicity, spectral broadening, and increased PSV indicate what
stenosis
if a waveform changes from triphasic to monophasic in 2 segments, look for what?
look for stenosis prox
-there will be increased resistance to flow
-significant stenosis can cause damped flow velocity
what happens distal to stenosis?
-decrease resistance
-monophasic
-may be dampened/no diastolic flow
-PI decreases
-acceleration time increases
as stenosis increases, PSV will increase and what will be lost?
spectral window
-PSV increases x 2 compared to pre stenotic V = 50% stenosis
-PSV increases x 4 = 75% stenosis
what is turbulence?
distal swirling of flow occurs causing wide range of reflected frequency shifts (large bandwidth), causes spectral broadening
-resistance drops distal to stenosis to encourage more inflow
stenosis leads to distal drop in PI and an increase in what?
acceleration time
damping factor
-evaluated by dividing the PI prox to stenosis by the PI distal to
-describes degree of attenuation of the doppler signal caused by stenosis
-PI will decrease distal to stenosis
-greater the stenosis, the lower the distal PI, and greater dampening factor
