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Arterial line insertion [advanced]

Please note this information is for educational purposes only and procedures should not conducted based on this information. OSCEstop and authors take no responsibility for errors or for the use of any content.

Indications: continuous blood pressure monitoring; frequent arterial blood gasses


Contraindications: absent pulse, Raynaud syndrome, thromboangiitis obliterans, inadequate circulation to extremity, burns over site, vascular graft/arteriovenous fistula


Sites: radial artery is preferred site and is outlined below; brachial artery may also be used if radial is not possible; ultrasound is not required but usually kept available in case it is needed


  • Wash hands, Introduce self, Patients name & DOB & wrist band, Explain procedure and get consent if possible
    • Risks: infection, bleeding/haematoma, arterial occlusion/permanent ischaemic damage, pseudoaneurysm/fistula formation, nerve damage
  • Ensure assistant is available and clinical and non-clinical bins are close by to dispose of waste

Preparation part

  • Wash hands and apply apron and face visor
  • Clean a trolley
  • Gather equipment onto bottom of trolley (think through what you need in order)

Equipment list

  • Cleansing snap-sponge (iodine or alcohol/chlorhexidine) x2
  • Arterial line kit
    • Drape with hole in centre
    • 5ml syringe (for local anaesthetic)
    • Orange 25G needle (for local infiltration)
    • Introducer needle (yellow top)
    • Arterial line with guidewire inside in correct orientation (has soft and firm ends – soft end goes into artery)
    • 5ml blood gas syringe
    • Note equipment in kits varies
  • Arterial line extension connector
  • Blunt fill 18G drawing-up needle
  • Externally sterile syringe of sterile 0.9% saline (or 10ml syringe + drawing up needle) for flush
  • Cannula dressing
  • Sterile ultrasound probe cover and gel
  • Equipment to be kept outside the sterile field
    • Sterile surgical gloves
    • Incontinence pad
    • Ultrasound machine (in case required)
    • 10ml 1% lidocaine (maximum 3mg/kg – note 1ml 1% lidocaine = 10mg)
    • 10ml 0.9% saline vial (for drawing up for flush if not using pre-prepared flush)

  • Walk to patient
  • Wash hands
  • Open the arterial line kit to form a large sterile field on the top of the trolley
  • Open packets (without touching the instruments themselves) and drop sterile instruments neatly into the sterile field
Arterial line insertion equipment

Patient part

Positioning and exposure

  • Position patient so wrist is accessible and hyperextended (use a folded clean towel if available)
  • Expose area
  • Palpate artery
  • Place incontinence pad under arm


  • Wash hands
  • Apply sterile gloves using sterile technique
  • Prepare equipment in order in sterile field
  • Remove sheath and cap from arterial line, and then remove guidewire (keeping it in the correct orientation)
  • Flush arterial line connector with 0.9% saline from non-threaded end, then clamp lumen and replace cap
    • If not using pre-prepared flush: ask assistant to snap open 0.9% saline vial and hold open upside-down; then draw up using drawing up needle on 10ml syringe; then remove needle and expel any air
  • Sterilize area
    • Work from middle outwards in one spiral motion (using cleansing snap-sponge)
    • Repeat this with 2nd cleansing snap-sponge
    • Discard used snap-sponges as they are no longer sterile, but note all equipment used after this (including all needles) can be returned to the sterile field after use
    • Apply the sterile drape over the area, so that the hole is in the correct place to allow access to the insertion site
    • Place guidewire in correct orientation in patient’s sterile field so it is readily accessible
  • Anaesthetise area
    • Ask assistant to snap open lidocaine bottle and hold open upside-down
    • Draw up lidocaine using drawing up needle on 5ml syringe and expel any air, then change to the orange 25G needle
    • Insert needle at an acute angle to form a large subcutaneous lidocaine bleb around insertion site in order to anaesthetise the skin, ensuring you aspirate before injection to avoid injection into a blood vessel
  • Now wait 1 minute for the anaesthetic to work

Seldinger insertion procedure

  • Introducer needle insertion
    • Insert the bare introducer needle into the radial artery
      • Pierce the skin at 15-30⁰
      • Advance very slowly into the artery, looking for pulsating blood coming from the end of the needle
      • Flatten needle to skin
    • If you are unsuccessful, remove and flush the needle with 0.9% saline and try again (consider using ultrasound if needed)
  • Guidewire insertion
    • Insert the soft end of the guidewire into the introducer needle, leaving a few centimetres to hold
    • From now on, keep hold of the guidewire at all times with one hand
    • Withdraw the needle and thread it right the way off the end of the guidewire, ensuring the guidewire remains in place
  • Catheter insertion
    • Thread the arterial catheter over the guidewire until the tip is near the skin
    • Now retract the guidewire slowly until the end comes out of the port
    • Holding the end of the guidewire, insert the catheter all the way into the artery
    • When the catheter is in place, remove guidewire
  • Aspirate blood with the blood gas syringe
  • Attach the flushed arterial line connector (with cap on and lumen clamped) – the threaded end attaches to the arterial line
  • Flush connector and then clamp and replace bung

Securing catheter

  • Dry any blood with gauze
  • Apply cannula dressing then film dressing over the top

To complete

  • Ask nursing staff to connect arterial line to transducer
  • Thank patient and cover them
  • Dispose of sharps safely in sharps bin, bin waste and gloves/apron, clean trolley, and wash hands
  • Fully document procedure in patients notes

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