CPHON Central Line Care and Vascular Access 2 — Questions and Answers
Question 1: What is the primary advantage of a tunneled central venous catheter (e.g., Broviac or Hickman) over a non-tunneled central line in pediatric oncology?
- The subcutaneous tunnel reduces CLABSI risk and allows long-term use over months to years (Correct answer)
- It has a larger lumen for faster blood product administration
- It can be placed without anesthesia at the bedside
- It eliminates the need for heparin flushes
Correct answer: The subcutaneous tunnel reduces CLABSI risk and allows long-term use over months to years
Tunneling the catheter under the skin creates a mechanical barrier to bacterial migration from the skin exit site to the bloodstream, reduces CLABSI rates, and makes the catheter suitable for long-term use (months to years) compared to non-tunneled devices.
In a tunneled catheter (Broviac, Hickman), the catheter is threaded subcutaneously 5–10 cm from the vessel entry site to a separate skin exit site, typically on the chest wall. A Dacron cuff around the catheter at the tunnel promotes fibrous tissue ingrowth, anchoring the device and creating a physical barrier to bacterial migration. This reduces CLABSI rates compared to non-tunneled percutaneous central lines. Tunneled catheters are suitable for months to years of use and are preferred for children undergoing prolonged chemotherapy, HSCT, or long-term parenteral nutrition. They require surgical or interventional radiology placement.
Question 2: A nurse is preparing to access an implanted venous port in a 7-year-old for chemotherapy. In what order should the following steps be performed?
- Apply topical anesthetic → palpate septum → clean with chlorhexidine → insert Huber needle → verify placement by aspirating blood → flush with normal saline (Correct answer)
- Insert Huber needle first → then apply antiseptic → verify by flushing → aspirate blood
- Aspirate first to confirm placement → then clean the site → insert needle → apply anesthetic
- Clean the site → insert Huber needle → apply anesthetic cream after insertion
Correct answer: Apply topical anesthetic → palpate septum → clean with chlorhexidine → insert Huber needle → verify placement by aspirating blood → flush with normal saline
The correct sequence for port access is: apply topical anesthetic (well in advance) → palpate the port septum → clean with chlorhexidine antiseptic → insert Huber needle perpendicular to septum → verify with blood aspiration → flush with normal saline.
Proper port access technique follows this sequence: (1) Apply topical anesthetic (EMLA or LMX) at least 30–60 minutes before access for pain management; (2) Perform hand hygiene and gather sterile supplies; (3) Palpate the port to locate the septum; (4) Apply chlorhexidine gluconate antiseptic to the skin and allow to dry completely; (5) Don sterile gloves; (6) Insert the non-coring Huber needle perpendicular to the septum, pressing through until the needle touches the back of the port chamber; (7) Verify placement by aspirating blood return; (8) Flush with normal saline to confirm patency and assess for swelling; (9) Connect infusion tubing.
Question 3: A 5-year-old's central line dressing appears soiled and has lifted at one edge. The catheter was last dressed 5 days ago. The nurse should:
- Perform an immediate dressing change using sterile technique with chlorhexidine-based antiseptic (Correct answer)
- Cover the lifted edge with medical tape and schedule a routine change tomorrow
- Remove the central line and insert a new one
- Apply antibiotic ointment to the exit site and re-tape
Correct answer: Perform an immediate dressing change using sterile technique with chlorhexidine-based antiseptic
A soiled, non-intact dressing requires immediate change regardless of the usual schedule. The compromised dressing no longer protects the exit site from microorganism entry, increasing CLABSI risk.
Central line dressing guidelines (based on CDC and INS standards) require changing the dressing whenever it is soiled, loosened, or damp — not just on a scheduled interval. Transparent semipermeable dressings are changed every 5–7 days; gauze dressings are changed every 48 hours. An intact dressing provides a physical barrier against skin flora migration to the catheter exit site. Chlorhexidine gluconate-impregnated dressings (CHG patches) are recommended for patients at high CLABSI risk. The dressing change should be performed aseptically, with chlorhexidine gluconate antiseptic applied and allowed to dry completely before applying the new dressing.
Question 4: Which action violates best practice when drawing blood cultures from a pediatric central venous catheter?
- Using the same catheter lumen for blood draw and antibiotic infusion simultaneously (Correct answer)
- Disinfecting the needleless connector with chlorhexidine before access
- Discarding the initial 5 mL of blood before collecting the culture sample
- Using a sterile syringe to aspirate blood
Correct answer: Using the same catheter lumen for blood draw and antibiotic infusion simultaneously
Drawing blood cultures through a lumen that is simultaneously used for antibiotic infusion risks contaminating the culture with the antibiotic, leading to false-negative cultures and inaccurate pathogen identification.
When obtaining blood cultures from a central line, each lumen must be accessed separately and should not be actively receiving antibiotics at the time of collection. If antibiotics are running, they should be stopped and the line flushed before culture collection to prevent false-negative results from antibiotic carry-over. Best practices include: disinfecting connectors with alcohol or chlorhexidine before access, discarding an appropriate 'dead space' volume (typically 3–5 mL in adults, less in children per institutional protocol) before drawing the culture sample, and using sterile technique throughout. This ensures the most accurate microbiological results.
Question 5: A child is receiving a continuous infusion through a double-lumen Broviac when the proximal lumen tubing disconnects accidentally. The most immediate nursing action is:
- Clamp the proximal catheter hub immediately, then apply a sterile cap while maintaining aseptic technique (Correct answer)
- Reattach the disconnected tubing quickly without cleaning the hub
- Remove the entire catheter to prevent air embolism
- Notify the physician before doing anything
Correct answer: Clamp the proximal catheter hub immediately, then apply a sterile cap while maintaining aseptic technique
Immediate clamping of the disconnected lumen prevents air entrainment (air embolism) and blood backflow. A sterile cap should then be placed on the hub using aseptic technique. The hub and connection should be cleaned with antiseptic before reconnecting new tubing.
Accidental central line disconnection is an emergency requiring immediate clamping of the exposed lumen to prevent two life-threatening complications: (1) air embolism — air can be rapidly sucked into the catheter and into the central venous circulation due to negative intrathoracic pressure, causing cardiorespiratory collapse; and (2) blood loss — blood may backflow out through the disconnected lumen. After clamping, apply a sterile cap to the catheter hub using aseptic technique. Do not reuse the contaminated tubing — prepare new sterile tubing. Clean the catheter hub with chlorhexidine or alcohol before reconnecting. Notify the provider and document the incident.
Question 6: What is the correct syringe size to use when flushing a pediatric central line, and why?
- 10 mL or larger, because smaller syringes generate dangerously high pressure that can rupture the catheter (Correct answer)
- 1 mL, because smaller syringes deliver flush more efficiently
- 3 mL syringes are preferred for all central line flushing
- Syringe size does not affect catheter pressure
Correct answer: 10 mL or larger, because smaller syringes generate dangerously high pressure that can rupture the catheter
Smaller syringes generate much higher pressures per unit force applied because the plunger area is smaller. Using syringes smaller than 10 mL (especially 1 mL or 3 mL) can exceed catheter pressure tolerances and cause rupture or catheter fracture.
By Boyle's law and basic pressure physics, the pressure generated in a syringe is inversely proportional to the cross-sectional area of the syringe barrel. A 1 mL syringe generates approximately 10 times more pressure per Newton of force than a 10 mL syringe. Most central venous catheters have pressure limits of 25–40 psi; small syringes can easily exceed these limits and cause catheter fracture or rupture — a serious complication requiring emergent catheter removal. The minimum recommended syringe size for flushing central lines is 10 mL (some power-injectable ports allow use with specific pressure-rated syringes). Nurses should NEVER use <10 mL syringes for CVC flushing.
CPHON Central Line Care and Vascular Access 2
What is the primary advantage of a tunneled central venous catheter (e.g., Broviac or Hickman) over a non-tunneled central line in pediatric oncology?