VT Dialysis Access Surveillance 3

Question 1

Which waveform characteristic best distinguishes a maturing AVF from a non-maturing one on duplex ultrasound?

Accepted Answer

Low-resistance monophasic flow with high diastolic component in brachial artery

Answer

A maturing fistula creates a low-resistance circuit; the feeding brachial artery shows high-velocity, low-resistance flow with a dominant diastolic component.

Question 2

A surveillance duplex reveals a focal hypoechoic outpouching adjacent to an AVG with a yin-yang color pattern on Doppler. What is the diagnosis?

Accepted Answer

Pseudoaneurysm

Answer

A perigraft outpouching with yin-yang swirling color flow is pathognomonic for a pseudoaneurysm, a common complication at needle puncture sites.

Question 3

During AVF surveillance, the brachial artery diameter is 5 mm and TAM velocity is 38 cm/s. What is the calculated access blood flow?

Accepted Answer

Approximately 560 mL/min

Answer

Flow = π × (0.25 cm)² × 38 cm/s × 60 s/min ≈ 0.0491 × 38 × 60 ≈ 112 mL/min — wait, radius is 0.25 cm; area = 0.196 cm²; flow ≈ 0.196 × 38 × 60 ≈ 447 mL/min — closest to 450; however, with r=0.25: flow≈447. Select 450 mL/min.

Question 4

What is the primary advantage of ultrasound dilution (transonic) over duplex Doppler for access flow monitoring?

Accepted Answer

It is more accurate and less operator-dependent for flow quantification

Answer

Ultrasound dilution is more reproducible and less operator-dependent than duplex Doppler for absolute flow quantification during dialysis sessions.

Question 5

A patient with a left brachiocephalic AVF complains of hand coolness and pain during dialysis. Duplex shows reversed flow in the distal radial artery. What complication is present?

Accepted Answer

Distal ischemic steal syndrome

Answer

Reversed flow in the distal radial artery during AVF function indicates blood is being stolen from the hand circulation, confirming steal syndrome.

(VT) Vascular Technician Certification Practice Test

(VT) Vascular Technician Certification Practice Test

VT Dialysis Access Surveillance 3