VABC Ultrasound Guidance 5 — Questions and Answers
Question 1: According to evidence-based guidelines, routine ultrasound confirmation of tip position via intracavitary ECG during PICC insertion detects tip malposition better than:
- Post-procedure chest X-ray alone (Correct answer)
- Color Doppler assessment of the SVC
- Short-axis view of the right atrium
- Fluoroscopy performed 24 hours post insertion
Correct answer: Post-procedure chest X-ray alone
Intracavitary ECG guidance provides real-time tip localization and has been shown to be equivalent to or better than chest X-ray for detecting malposition at time of insertion.
Question 2: Posterior wall puncture during ultrasound-guided venipuncture most often occurs because:
- The needle gauge is too large for the vessel
- The needle is advanced too quickly through the near wall without pausing to confirm intraluminal entry (Correct answer)
- The probe frequency is too low for the vessel depth
- Trendelenburg position is not used
Correct answer: The needle is advanced too quickly through the near wall without pausing to confirm intraluminal entry
Advancing the needle past the near wall without confirming flashback or intraluminal position on ultrasound commonly results in posterior wall puncture.
Question 3: When assessing for pneumothorax after subclavian/axillary vein cannulation using lung ultrasound, the absence of which sign confirms no pneumothorax?
- A-lines
- Lung sliding (Correct answer)
- B-lines
- Seashore sign on M-mode
Correct answer: Lung sliding
Lung sliding (the shimmer of visceral over parietal pleura with respiration) is absent in pneumothorax; its presence confirms the lung is apposed to the chest wall.
Question 4: Which patient population most benefits from routine ultrasound guidance for peripheral IV access compared to standard landmark technique?
- Pediatric patients under 2 years with normal veins
- Adult patients with difficult venous access (DIVA) (Correct answer)
- Elderly patients with prominent superficial veins
- Athletes with high muscle mass but palpable veins
Correct answer: Adult patients with difficult venous access (DIVA)
Patients classified as difficult intravenous access (DIVA) — those with prior IV failure, obesity, history of IV drug use, or sickle cell disease — derive the greatest benefit from ultrasound guidance.
Question 5: During ultrasound-guided IJ cannulation, the probe is rotated 90 degrees from short-axis to long-axis view primarily to:
- Confirm the absence of thrombus in the vessel
- Visualize the needle advancing in-plane toward the vessel (Correct answer)
- Assess vessel compressibility more accurately
- Measure the vessel diameter for catheter sizing
Correct answer: Visualize the needle advancing in-plane toward the vessel
Rotating to long-axis allows the needle to be seen in-plane, enabling continuous visualization of the needle tip and shaft as it advances toward and enters the vessel.
Question 6: A vascular access nurse notices spontaneous collapse of the target vein during ultrasound scanning without probe pressure. The most likely explanation is:
- Venous thrombosis occluding the lumen
- Hypovolemia causing low venous pressure (Correct answer)
- Arterial compression of the adjacent vein
- Probe frequency mismatch causing artifact
Correct answer: Hypovolemia causing low venous pressure
Spontaneous venous collapse without external pressure is a classic ultrasound finding in hypovolemic or dehydrated patients due to decreased central venous pressure.
Question 7: According to INS and AVA standards, real-time ultrasound guidance during PICC and central venous catheter insertion is classified as:
- Optional adjunct reserved for difficult access only
- Standard of care that should be used whenever feasible (Correct answer)
- Contraindicated when fluoroscopy is available
- Required only in pediatric patients
Correct answer: Standard of care that should be used whenever feasible
INS and AVA guidelines designate real-time ultrasound guidance as the standard of care for PICC and CVC insertion whenever available, regardless of patient difficulty level.
VABC Ultrasound Guidance 5
According to evidence-based guidelines, routine ultrasound confirmation of tip position via intracavitary ECG during PICC insertion detects tip malposition better than: