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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 takes no responsibility for 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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