VABC Maintenance & Troubleshooting of Vascular Access Devices 4 — Questions and Answers
Question 1: Pinch-off syndrome is a mechanical complication specific to which type of vascular access device?
- PICCs inserted at the basilic vein
- Subcutaneously implanted ports with catheters placed via the subclavian vein (Correct answer)
- Femoral central venous catheters
- Tunneled catheters placed via the internal jugular vein
Correct answer: Subcutaneously implanted ports with catheters placed via the subclavian vein
Pinch-off syndrome occurs when the catheter of a subclavian-inserted port is compressed between the clavicle and first rib, causing intermittent or complete occlusion and catheter fracture risk.
Question 2: A patient with an implanted port reports positional blood return — return is present when the arm is raised but absent in a neutral position. The MOST likely cause is:
- Fibrin sheath formation
- Drug precipitate occlusion
- Catheter tip malposition (Correct answer)
- Internal jugular thrombus
Correct answer: Catheter tip malposition
Positional blood return that changes with arm or body position strongly suggests catheter tip malposition into a smaller vessel or against a vessel wall.
Question 3: Which radiographic finding on chest X-ray confirms that a PICC tip is correctly positioned?
- Tip at the junction of the subclavian and innominate veins
- Tip in the upper one-third of the superior vena cava (SVC)
- Tip at the cavoatrial junction (lower SVC/right atrium junction) (Correct answer)
- Tip inside the right atrium
Correct answer: Tip at the cavoatrial junction (lower SVC/right atrium junction)
The optimal PICC tip position is at or just above the cavoatrial junction (lower SVC), which ensures adequate blood flow for hemodilution of infusates.
Question 4: A fibrin sheath encasing a catheter tip is BEST treated with which pharmacologic intervention?
- Systemic anticoagulation with heparin infusion
- Alteplase (tPA) dwell followed by forceful aspiration (Correct answer)
- Warfarin therapy for 3 months
- Intravenous vancomycin
Correct answer: Alteplase (tPA) dwell followed by forceful aspiration
Alteplase dwell therapy can dissolve fibrin sheaths; if unsuccessful, radiologic stripping of the sheath may be required.
Question 5: When a patient experiences sudden onset of dyspnea, chest pain, and hypotension during central line tubing change, air embolism should be suspected. What is the IMMEDIATE positioning intervention?
- Semi-Fowler's position with head elevated 30 degrees
- Left lateral decubitus (Durant's maneuver) with Trendelenburg positioning (Correct answer)
- Prone position with arms at sides
- Right lateral decubitus with legs elevated
Correct answer: Left lateral decubitus (Durant's maneuver) with Trendelenburg positioning
Left lateral decubitus with Trendelenburg (head down) positions the air bubble in the right ventricle apex, preventing it from entering the pulmonary circulation.
Question 6: Which characteristic MOST reliably differentiates catheter-related bloodstream infection (CRBSI) from a contaminated blood culture?
- Patient has a fever above 38.5°C
- Differential time to positivity (DTP) ≥2 hours between catheter and peripheral cultures (Correct answer)
- White blood cell count above 12,000
- Presence of coagulase-negative Staphylococcus in the culture
Correct answer: Differential time to positivity (DTP) ≥2 hours between catheter and peripheral cultures
A differential time to positivity ≥2 hours (catheter culture positive before peripheral) is a validated diagnostic criterion indicating the catheter is the infection source.
Question 7: After alteplase instillation for a thrombotic occlusion fails to restore patency, the NEXT appropriate step is:
- Remove the catheter immediately
- Repeat alteplase with a higher concentration (2 mg/mL)
- Repeat the alteplase dwell for a second instillation up to 2 hours, then consider imaging (Correct answer)
- Administer systemic thrombolytics intravenously
Correct answer: Repeat the alteplase dwell for a second instillation up to 2 hours, then consider imaging
If the first alteplase dwell does not restore patency, a second instillation is appropriate; if both fail, imaging studies are indicated to evaluate for fibrin sheath or other structural causes.
VABC Maintenance & Troubleshooting of Vascular Access Devices 4
Pinch-off syndrome is a mechanical complication specific to which type of vascular access device?