Central venous and arterial access in children — formative SAQs

SAQ 1 (10)

A 3-year-old, 14 kg child in septic shock needs central venous access to deliver an adrenaline infusion, and is also thrombocytopenic with a platelet count of 35. You are asked to place the line. ^[8]

1. State and justify the central venous site you would choose for this child, and explain why the subclavian site is avoided. (4) ^{[3] [8]}
2. Outline the steps of the ultrasound-guided Seldinger technique you would perform at your chosen site. (4) ^[1]
3. Describe how you would confirm correct catheter tip position, and outline your CLABSI prevention bundle. (2) ^{[11] [12]}

Model answer

Site choice and why subclavian is avoided. The femoral vein is the first choice for this child. It is fully compressible against the pubic ramus, it is pneumothorax-free, and it can be placed while the child is being resuscitated without turning the head, which suits the emergency setting. The subclavian vein is avoided in a thrombocytopenic child because the subclavian artery lies behind the clavicle and cannot be compressed; a subclavian arterial puncture bleeds invisibly into the chest and can become a haemothorax. The femoral vein lies medial to the femoral artery in the femoral sheath, the NAVL relationship, which makes it ultrasound-friendly and safe. ^{[3] [8]}

Ultrasound-guided Seldinger technique. Identify the femoral vein in a short-axis view just below the inguinal ligament, confirming it is the medial, compressible, non-pulsatile structure relative to the artery. Prepare the skin with chlorhexidine and allow it to dry, apply full barrier precautions, and raise a skin wheal with lidocaine 1 per cent (maximum 3 mg/kg without adrenaline). Advance the needle to the vessel under ultrasound, watching the tip enter the lumen, and confirm dark non-pulsatile venous blood. Pass the guidewire through the needle, withdraw the needle, make a small skin nick, dilate the tract, and railroad the catheter over the wire. Remove the wire, aspirate and flush every lumen, secure the line, and confirm the tip. ^[1]

Tip confirmation and CLABSI bundle. Confirm the tip at the cavoatrial junction on a post-procedure chest radiograph, or by ultrasound-based tip navigation such as the ECHOTIP approach, and exclude a pneumothorax. The CLABSI prevention bundle is full barrier precautions at insertion, chlorhexidine skin antisepsis, a chlorhexidine-impregnated dressing, scrub-the-hub before each access, avoidance of routine flushing, and a daily review of line necessity with prompt removal. ^{[11] [12]}