Ultrasound Evaluation of Dialysis Catheter
Normal fisula are monophasic with PSV of 100-400 cm/sec (EDV of 60-200 cm/s). Draining veins PSV of 30-100 cm/sec.
Stenosis= increased PSV, decreased lumen.
Arterial Ultrasound Lower extermity
"Although the US diagnostic criteria for detecting significant stenosis of lower extremity arteries are based on Doppler US findings in many studies , consensus has not been reached on the validated cutoff value. Some studies apply a PSV ratio of 2.0 as a means of differentiating between stenoses of less than 50% diameter reduction and those of greater than 50% reduction, whereas others use 2.5 or 3.0 as a cutoff value. A meta-analysis by Visser and Hunink compared the diagnostic performance of duplex US with that of conventional angiography in detecting significant stenosis from peripheral arterial occlusive disease. Duplex US demonstrated a sensitivity of 87.6% and a specificity of 94.7% and less discriminatory power than MR angiography. Furthermore, duplex US evaluation of the arteries of an entire lower extremity is operator dependent and labor intensive and does not provide a “road map” equivalent to that provided by angiography. Thus, duplex US would be expected to play only a supplementary role in evaluating restricted segments of lower extremity arteries."
Aortic Ultrasound.
Vascular
Waveforms obtained from the distal abdominal aorta near the iliac bifurcation usually have a higher-resistance flow pattern, reflecting the peripheral resistance of the lower extremity arteries. Waveforms obtained from the peripheral arteries demonstrate a triphasic character in the resting state with reversal of flow during diastole. This is due to branching into smaller arteries and capillary beds. The average velocity range for the abdominal aorta is 60 to 100 cm/sec. Report if velocity is over 200 cm/sec
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