Indications

• Frequent monitoring of blood gases

• Direct monitoring of arterial blood pressure

• Exchange transfusion (peripheral venous and arterial catheters ‛continuous’ technique) or partial exchange transfusion 

Contraindications

• Bleeding disorder
• Inadequate patency of ulnar artery on transillumination or failed Allen’s test (if cannulating radial artery) or vice-versa
• Pre-existing evidence of circulatory insufficiency in limb
• Local skin infection
• Malformation of limb being considered for line insertion

Possible sites of arterial entry

• Radial (most used); the only procedure discussed in this guideline
• Posterior tibial 
• Dorsalis pedis 

• Gloves
• Cleaning solution as per unit policy
• 24 G cannula
• T-connector with Luer lock
• Adhesive tape
• Splint
• Sodium chloride 0.9% flush in 2 mL syringe, primed through T-connector
• Transillumination fibre-optic light source
• 3-way tap

Preparation

• Wash hands 
• Check patency of ipsilateral ulnar artery using Allen’s test and proceed only if patent
• Put on gloves
• Extend baby’s wrist with palm of hand upwards
• Transilluminate radial artery with fibre-optic light source behind baby’s wrist or palpate pulse
• Clean skin with antiseptic cleaning solution

Procedure

• Enter artery with 24 G cannula just proximal to wrist crease at 25–30° angle
• Remove stylet from cannula and advance cannula into artery
• Connect cannula to T-connector primed with sodium chloride 0.9%, and flush gently
• Secure cannula with tape, ensuring fingers are visible for frequent inspection, and apply splint
• Connect T-connector to infusion line (sodium chloride 0.9% or 0.45% with heparin 1 unit/mL), with 3-way tap in situ for blood sampling 

Documentation

• Document clearly in notes all attempts at cannulation, including those that are unsuccessful

Monitor

• Inspect distal digits regularly for circulatory status; if blanching does not recover after 5 min, discuss further management with consultant
• Avoid excessive hyperextension of wrist, as this can result in occlusion of artery
• Ensure a continuous pressure waveform tracing is displayed on monitor screen at all times; if flushing line does not restore lost tracing, change position of limb/dressing

Usage

• Do not administer rapid boluses of fluid as this can lead to retrograde embolisation of clot or air; use minimal volume when flushing after sampling and inject slowly
• Use cannula only for sampling or removal of blood during exchange transfusion, and infuse sodium chloride 0.9% or 0.45% with heparin 1 unit/mL
• Remove cannula as soon as no longer required

Removal

• Aseptic removal of arterial line: apply pressure for ≥5 min (longer if coagulopathy/low platelets), until no bleeding 
  • dressings do not prevent bleeding or bruising
  • do not send tip for culture routinely 

• Thromboembolism/vasospasm/thrombosis

• Blanching and partial loss of digits (radial artery)

• Necrosis

• Skin ulceration

• Reversible occlusion of artery 

• Extravasation of sodium chloride infusate

• Infection (rarely associated with line infection)

• Haematoma

• Haemorrhage

• Air embolism