VABC Ultrasound Guidance 2 — Questions and Answers
Question 1: Which ultrasound view is preferred when initially confirming guidewire position in the vessel before dilation?
- Short-axis (transverse) view
- Long-axis (longitudinal) view (Correct answer)
- Oblique view
- M-mode view
Correct answer: Long-axis (longitudinal) view
The long-axis view allows visualization of the guidewire along its entire length within the vessel, confirming intraluminal placement before dilation.
Question 2: What artifact appears as a bright echogenic line with posterior acoustic shadowing when the ultrasound beam strikes a needle at 90 degrees?
- Ring-down artifact
- Reverberation artifact
- Specular reflection (Correct answer)
- Comet-tail artifact
Correct answer: Specular reflection
Specular reflection occurs when the ultrasound beam strikes a smooth surface (such as a needle) perpendicularly, producing a bright echogenic interface with acoustic shadowing.
Question 3: During ultrasound-guided PICC insertion, the basilic vein is preferred over the cephalic vein primarily because:
- It is more superficial and easier to compress
- It has a larger diameter and fewer valves (Correct answer)
- It follows a straighter path to the subclavian vein
- It has higher flow velocity
Correct answer: It has a larger diameter and fewer valves
The basilic vein is typically larger in diameter and has fewer valves than the cephalic vein, reducing resistance during catheter advancement.
Question 4: What is the primary purpose of applying color Doppler during ultrasound-guided vascular access?
- To measure vessel depth
- To differentiate artery from vein (Correct answer)
- To assess needle tip echogenicity
- To calculate vessel compressibility
Correct answer: To differentiate artery from vein
Color Doppler detects blood flow direction and pulsatility, reliably distinguishing arterial (pulsatile) from venous (continuous or respiratory-phasic) flow.
Question 5: When using the short-axis approach for internal jugular vein cannulation, inadvertent arterial puncture is most commonly detected by:
- Loss of vessel compressibility on probe pressure
- Bright red, pulsatile blood flashback in the syringe (Correct answer)
- Vessel collapse during Valsalva maneuver
- Increased depth of the target vessel
Correct answer: Bright red, pulsatile blood flashback in the syringe
Pulsatile bright red blood return in the syringe is the classic indicator of unintentional arterial puncture during internal jugular cannulation.
Question 6: Which maneuver can increase the diameter of the internal jugular vein to facilitate ultrasound-guided cannulation?
- Sitting the patient upright at 90 degrees
- Placing the patient in Trendelenburg position (Correct answer)
- Asking the patient to perform a Valsalva maneuver only during needle insertion
- Applying firm probe pressure over the vessel
Correct answer: Placing the patient in Trendelenburg position
Trendelenburg (head-down) positioning increases venous return and distends the internal jugular vein, making it a larger and easier target.
Question 7: In ultrasound imaging, 'anisotropy' of a vessel wall or tendon refers to:
- Increased echogenicity at greater depths
- Change in echogenicity depending on the angle of the ultrasound beam (Correct answer)
- Shadowing artifact posterior to calcifications
- Reverberations caused by parallel reflectors
Correct answer: Change in echogenicity depending on the angle of the ultrasound beam
Anisotropy is the phenomenon where tissue echogenicity changes with beam angle, most notable in tendons and can cause vessels to appear falsely echogenic when not insonated perpendicularly.
VABC Ultrasound Guidance 2
Which ultrasound view is preferred when initially confirming guidewire position in the vessel before dilation?