Insertion of peripheral arterial line for patients of the Neonatal Unit

Publication: 28/02/2014  --
Last review: 14/02/2020  
Next review: 06/02/2023  
Standard Operating Procedure
ID: 3691 
Approved By: Trust Clinical Guidelines Group 
Copyright© Leeds Teaching Hospitals NHS Trust 2020  


This Standard Operating Procedure is intended for use by healthcare professionals within Leeds unless otherwise stated.
For healthcare professionals in other trusts, please ensure that you consult relevant local and national guidance.

Insertion of peripheral arterial line for patients of the Neonatal Unit

Background and indications for standard operating procedure

Indwelling peripheral arterial cannulae (PAC) are used when1:

  • Continuous monitoring of blood pressure is required in intensive or high dependency care
  • Frequent blood sampling is required, especially arterial blood gases.

Arterial cannulae are normally only used during short periods of acute or critical illness.

Umbilical arterial lines are the arterial line of choice in the newborn infant. PAC may be used when umbilical lines are not possible because of inability to access or age. PAC should only be sited in the radial, ulnar, posterior tibial or dorsalis pedis arteries. The brachial artery must never be used as it is an end artery and as such, there is no collateral circulation.

Before any attempt is made to cannulate an artery an Allen’s test (see below) must be done to assess collateral circulation.

PACs should only be used for invasive monitoring of blood pressure and blood sampling/withdrawal. A PAC must NOT be used for drugs or fluid administration other than a slow continuous infusion of heparinised 0.9% saline that maintains line patency.

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Procedure method (step by step)

Infection Prevention and Control

    • Insertion should take place in an appropriate clinical area.
    • Strict hand hygiene must be followed Hand Hygiene Policy
    • An aseptic technique must be used (LTHT Asepsis Policy).
    • All cannulation equipment must be sterile prior to use and sterile examination gloves and an IV cannulation pack must be used to undertake the procedure.

Cannulation should only be performed by a practitioner who has the relevant knowledge and skills to do so. Practitioners must be observed and assessed for competence before operating solo.

An insertion attempt is defined as one needle puncture of the skin. Peripheral arterial cannula attempts must be limited to one attempt (one needle puncture) by each health care professional unless the artery remains undamaged, when a second attempt is acceptable. If a baby is deemed to have difficult arterial access, an experienced operator should make the first attempt. For each separate attempt, the skin must be cleaned again with fresh ChloraPrep® and a new cannulation pack and new cannula used.

Metal trolleys should be used, and must be decontaminated with Sani-cloth before use (see Trust IPC asepsis video ). The operator and/or assistant should prepare all necessary equipment on the clean trolley.
Once the operator is sterile, if further equipment is required, the observer must fetch and open packs.

Equipment required;
Peripheral cannulation pack
24 gauge “yellow” cannula
5mL 0.9% saline
2mL syringe (x2 if blood sampling required)
Heparinised syringe (for blood gas sampling if required)
Drawing up needle
Primed arterial connector with three ­way tap
Pharmacy prepared heparinised saline 50mL syringe with primed line
Alaris pump
A fibre-optic light to transilluminate the vessel may help

Possible sites for cannulation

  • Radial artery (providing the ulnar artery on that same hand has NOT been used previously)
  • Ulnar artery (providing the radial artery on that same hand has NOT been used or traumatised previously)
  • Posterior tibial artery
  • Dorsalis pedis

Cannulation should not be attempted if the skin is broken, bruised or infected.

Before any attempt at PAC insertion an Allen’s test must be performed and the result documented in the case notes

Testing for collateral circulation (Allen's test)2
The Allen’s test should be performed prior to the insertion of a peripheral arterial cannula to assess the collateral artery’s ability to supply an adequate amount of blood distal to the cannula site.

Radial artery3
Elevate the hand and occlude both radial and ulnar arteries at the wrist. Then massage the palm toward the wrist. Release the occlusion on the ulnar artery only. Look for re­perfusion in 10 seconds, which will indicate adequate collateral supply. Do not use the radial artery if re­perfusion takes longer.

Posterior tibial artery
Perform same test by raising foot and occluding dorsalis pedis and posterior tibial arteries, though it may be difficult to achieve full occlusion.

Analgesia should be for the procedure. See Procedural Pain in the Newborn

Peripheral arterial cannulation should be carried out aseptically.
There must be an assistant and operator.

  1. Assemble all equipment
  2. Identify suitable site
  3. Perform Allen’s test to check for adequacy of collateral circulation.
  4. Wash hands and dry thoroughly using towel in cannulation pack.
  5. Put on sterile gloves
  6. Prepare all equipment
  7. If using insert the fibre-­optic light cable and tip into sterile glove/sleeve with help of assistant
  8. Clean skin with ChloraPrep® according to guidance
  9. Establish a sterile field
  10. Slightly extend the wrist/ankle to bring the artery closer to the surface.
  11. Identify the artery by palpation or by transillumination
  12. Insert the cannula through the puncture in the skin at a 30° angle to the skin surface.
  13. Puncture the artery and watch for blood in the hub of the cannula.
  14. Advance slowly – there may be arteriospasm as the artery is touched and blood return may be delayed.
  15. Withdraw the stylet and advance the cannula into the artery as far as possible.
  16. Blood for analysis may be withdrawn at this stage by occluding the artery, removing the stylet and attaching an empty 2mL syringe.
  17. Withdraw required sample, occlude artery and disconnect syringe.
  18. Attach the cannula to the arterial connector and three­-way tap and slowly flush with 0.9% saline.
  19. Observe for pulsatile blood flow in the line and slowly flush through the cannula again.
  20. Turn off the three-way tap.
  21. Secure the cannula with steri-strips and clear dressing (Tegaderm) to allow for continuous sight of the skin entry site.
  22. Ensure that digits are clearly visible after securing limb to splint.
  23. Attach a transducer and monitor and ensure pulsatile trace.
  24. When assistant and operator are happy with trace and line fixation the operator may de-scrub.
  25. Document procedure using the specific sticker that is then placed in the patient’s case notes.

Maintenance: maintaining patency5

  • To maintain patency an intra-vascular pressurised infusion should be maintained through the cannula
  • Intermittent irrigation is not advocated and not recommended
  • Heparinised 0.9% sodium chloride should be continually infused to maintain
  • The recommended concentration is 1unit of heparin per mL of 0.9% sodium chloride
  • Administer a continuous infusion at 0.5-1mls/ hour via a syringe pump. The infusion pressure must be higher than intra-arterial pressure.
  • Manual flushing of the intra-arterial administration set should be kept to a minimum
  • Following blood sampling, always flush the line.
  • The administration set must be changed every 72 hours or more frequently if clinically indicated.
  • The cannula does not need to be routinely changed but only if clinically indicated.

Maintenance: observations

  • The cannula site must be exposed and continuously observed by trained and competent practitioners
  • Any abnormalities should be reported to the medical staff immediately
  • The PAC must be removed immediately if the arterial monitor trace is lost and it cannot be sampled, despite troubleshooting.
  • The circulation of the cannulated limb should be continuously monitored for signs of the following
    • cyanosis
    • decreased pulse
    • blanched colour
    • cool skin/extremities
    • sluggish capillary refill time
    • bleeding
  • The cannula must be removed if there is sustained blanching to the limb, distal to the cannula site
  • Observe for signs of cannula displacement into the tissues, which will be
    • swelling
    • bleeding
    • lack of a normal arterial waveform
    • fluid leakage
    • blanching
    • pain or discomfort
  • Observe the tissue surrounding the cannula for signs of infection
    • pain
    • redness
    • pus
    • temperature change
    • swelling
  • Accidental removal of the arterial cannula will require immediate application of pressure to the site for 5-15 minutes or until bleeding has stopped. The site should be covered with a sterile dressing until site has healed.

Removal of Peripheral Arterial Cannula
The arterial line should be removed when;

  • limb circulation is compromised
  • the cannula is misplaced
  • it is no longer required for monitoring and frequent blood sampling
  • there are signs of an infection

Gather the following equipment:

  • Dressing pack
  • surgical tape

To remove the line:

  • Open packaging.
  • Perform hygiene hand wash and put on gloves
  • Place equipment on clean tray using aseptic and non-touch technique.
  • Loosen all dressings.
  • Withdraw the line from the artery without applying pressure.
  • Using the sterile gauze immediately apply pressure for up to 5 minutes or until bleeding has stopped.
  • Cover the site with a small piece of gauze and tape
  • Observe the site regularly for bleeding every five mins for the first 15 minutes, then every hour.

If an arterial line is removed because of concerns about the circulation
distal to the insertion site, document this and highlight to ensure that future attempts at cannulation avoid the site.


Record: 3691


  • To standardise and optimise the insertion of peripheral arterial cannulae (PAC).
  • To optimize the maintenance of PAC and their complications
  • To standardize the uses of PAC
  • To standardize the removal of PAC.
Clinical condition:
Target patient group:
Target professional group(s): Secondary Care Doctors
Secondary Care Doctors
Adapted from:

Evidence base

  1. MacDonald MG. (2002) Peripheral artery cannulation. Ch 29. In: MacDonald MG, Ramasethu J. Atlas of procedures in neonatology. 3rd Ed. Lippincott Williams & Wilkins. Philadelphia. [IV]
  2. Cable (1999) The Allen test. Annals of Thoracic Surgery. March;67(3):876­7. [IV]
  3. McConnell EA. (1997) Performing Allen's test. Nursing. 27(11):26. [IV]
  4. Clinical Guideline: Peripheral Arterial Cannulation. Norfolk, Suffolk & Cambridgeshire Neonatal Network
  5. Clinical guidelines. Arterial lines in infants and children, Great Ormond Street Hospital.

Evidence levels:
A. Meta-analyses, randomised controlled trials/systematic reviews of RCTs
B. Robust experimental or observational studies
C. Expert consensus.
D. Leeds consensus. (where no national guidance exists or there is wide disagreement with a level C recommendation or where national guidance documents contradict each other)

Approved By

Trust Clinical Guidelines Group

Document history

LHP version 1.0

Related information

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