Central venous and arterial access in children — viva

Opening (must-hit)

"Central venous and arterial access in children is the ultrasound-guided placement of a central line whose tip sits at the cavoatrial junction, or of an arterial line for beat-to-beat pressure and blood-gas sampling, performed through a sterile Seldinger sequence. I choose the site by indication and bleeding risk — internal jugular for ultrasound visibility, femoral for the emergency or coagulopathic child, subclavian for long-term tunnelled access — and I never use the subclavian site in a bleeding child because it cannot be compressed. I run needle, guidewire, dilator, catheter under direct ultrasound, confirm the tip, and apply a full CLABSI prevention bundle with a daily review of line necessity." [1] [8] [12]

Branch A — Site selection in the bleeding child

Examiner: A 3-year-old in septic shock is thrombocytopenic with a platelet count of 35. Which central site, and why? Candidate: The femoral vein. It is compressible against the pubic ramus, it is pneumothorax-free, and it can be placed during resuscitation without turning the head. I avoid the subclavian vein entirely because the subclavian artery sits behind the clavicle and cannot be compressed; a puncture there bleeds invisibly into the chest. The internal jugular is a compressible alternative if the femoral is unsuitable. The femoral vein lies medial to the artery in the sheath, the NAVL relationship. [8]

Branch B — The Seldinger sequence

Examiner: Talk me through the Seldinger technique at the femoral site. Candidate: I identify the femoral vein in a short-axis view, confirm it is the medial, compressible, non-pulsatile structure, prepare the skin with chlorhexidine, and apply full barrier precautions. I raise a skin wheal with lidocaine, advance the needle to the vessel under ultrasound, confirm dark venous blood, pass the guidewire through the needle, withdraw the needle, dilate the tract, and railroad the catheter over the wire. I remove the wire, aspirate and flush every lumen, secure the line, and confirm the tip. I never lose sight of the wire and I always confirm the wire is out at the end. [1]

Branch C — Ultrasound evidence

Examiner: Why is ultrasound now the standard of care for the internal jugular, and is the evidence as strong for subclavian and femoral? Candidate: Brass and colleagues' Cochrane review showed ultrasound guidance reduced failed attempts, arterial punctures and haematomas for internal jugular cannulation, and Sigaut's paediatric meta-analysis agreed. For subclavian and femoral sites the adult evidence was less clear, but in children the small-vessel problem keeps ultrasound central to practice. Nardi and Pang showed ultrasound-guided subclavian cannulation is effective and non-inferior to fluoroscopy in children. [2]

Branch D — Arterial line and the Allen test

Examiner: A child needs a radial arterial line. What do you do first, and what size cannula? Candidate: An Allen test. I compress radial and ulnar arteries, blanch the palm by clenching and opening the fist, release the ulnar, and look for brisk reperfusion. If the palm reperfuses, the ulnar collateral supply is adequate and the radial artery is safe. I use a 22 gauge cannula in an older child and a 24 gauge in an infant, under ultrasound, and I transduce to a crisp arterial waveform to confirm placement. A delayed or absent Allen test pushes me to another site. [5]

Branch E — Complication at insertion

Examiner: During an internal jugular attempt you get bright pulsatile blood. What now? Candidate: That is a carotid puncture. I withdraw the needle and apply firm sustained proximal pressure for several minutes, longer than feels necessary, because the danger is an unrecognised arterial puncture or insufficient pressure. I reassess the vessel under ultrasound and reposition before reattempting. I do not pass a wire into an artery and I do not flush the needle. If the child destabilises, I stop the procedure and manage the child first. [8]

Branch F — After the line is in

Examiner: The line is placed and the tip looks good. What now, and what is your infection plan? Candidate: I secure the line, label each lumen, aspirate and flush all lumens, and confirm the tip at the cavoatrial junction on a chest radiograph or by ultrasound tip navigation. I monitor the child in an intensive-care setting. My CLABSI prevention bundle is full barrier precautions at insertion, chlorhexidine skin antisepsis, a chlorhexidine-impregnated dressing, scrub-the-hub before each access, no routine flushing, and a daily review of line necessity with prompt removal. The line comes out the moment it is no longer needed. [12]

Branch G — Long-term device choice

Examiner: An oncology child needs chemotherapy for many months and wants to swim. What device? Candidate: A totally implantable port. It sits entirely beneath the skin and is accessed through the skin with a needle when needed, so there is nothing external between treatments and the child can swim and bathe. A tunnelled Hickman or Broviac is an alternative for continuous access but has an external segment that limits swimming. I avoid repeated acute lines because each carries its own cumulative infection risk, and I apply the CLABSI bundle rigorously in the immunocompromised child. [7]