Peripheral arterial access in neonates requiring intensive care

Peripheral arterial access should not be considered in neonates with:

• unsuccessful modified Allen’s test (evidence of inadequate collateral flow)
• inadequate circulation to the extremity
• uncorrected coagulopathy
• local skin infection
• limb malformation, bone fracture 
• recent cannulation or attempt of another artery in the same limb.

Peripheral arterial access carries risks of:

• thrombo-embolism/vasospasm/thrombosis, which can lead to compromise of arterial circulation, blanching, necrosis or gangrene of tissues or extremities
• damage to peripheral nerves
• emboli
• haematoma
• infection
• aneurysm of punctured artery 
• nerve/tendon damage.

If in doubt TAKE IT OUT.

Sites for peripheral artery catheters

The following sites are recommended for peripheral artery catheters:

• radial artery
• posterior tibial artery
• dorsalis pedis artery
• ulnar artery (as a last resort and ONLY if radial artery on the same limb has not been previously accessed).

The risk of ischaemia secondary to radial or ulnar arterial cannulation is approximately 5 per cent. The dorsalis pedis artery can be used if palpated (however it is absent in some infants). The brachial artery should not be used due to absence of collateral circulation.

Perform a modified Allen’s test to check for adequacy of collateral circulation if using an upper limb. The Allen's test is a measurement of radial or ulnar patency. Performing the Allen's test in a neonate involves elevating the arm and simultaneously occluding the radial and ulnar arteries at the wrist, then rubbing the palm to cause blanching. Release the pressure on the ulnar artery (see Figure 1). If normal colour returns to the palm in < 10 seconds, adequate ulnar circulation is present.

Performing and reporting the results of the Allen's test must be documented in the medical record.

The following equipment is needed for peripheral arterial cannulation:

• cleaned procedure trolley
• infrared trans-illuminator
• sterile dressing pack, sterile gloves, protective eye-wear (including for assistant)
• antiseptic solution (i.e. 2% chlorhexidine and 70% alcohol)
• 24G intravenous cannula
• 5 mL luer lock syringe with sodium chloride 0.9% mixed with heparin 1 unit/mL (draw up 0.5 mL of 50 units/mL heparin and 4.5 mLs of sodium chloride 0.9%)
• T piece connector (IV cannula extension) with 3-way tap primed with 0.9% sodium chloride
• prepared IV giving set primed with heparinised (one unit of heparin per mL) sodium chloride 0.9% or sodium chloride 0.45%
• arterial line set primed using ANTT with sodium chloride 0.9%
• tapes for securing the line, splint /arm-board - steri-strips, Elastoplast and Tegaderm (or equivalent)
• long extension line – minimum volume extension tubing
• syringe prepared with 50 mL saline and 50 units heparin
• transducer set and cable
• syringe pump

This is a painful procedure. In most instances a neonate requiring an arterial line is unwell and will usually have morphine and/or midazolam infusion prescribed. A bolus may be required prior to commencement of the procedure. Oral sucrose can be given if no contraindications apply. Neonate may be swaddled (with affected limb exposed for access) during procedure and offered non-nutritive sucking for comfort if appropriate.

• Maintain thermoregulation throughout procedure.
• Avoid hyperextension of the joint as this may lead to occlusion of the artery.
• Attempt insertion of no more than one artery.
• Seek senior help before further attempts.
• Always ensure that the tips of the fingers and toes are exposed so that perfusion can be checked regularly.
• Do not infuse blood, medications or hypertonic solutions via a peripheral arterial line.

• Wash hands and prepare work surface and equipment.
• Perform Allen's test to check for adequacy of collateral circulation.
• Slightly extend the wrist/ankle to bring the artery closer to the surface.
• Identify the artery by palpation +/- trans-illumination.
• Rewash hands and don sterile gloves.
• Clean the skin with chlorhexidine solution.
• Insert the 24G cannula over the artery at an angle of 30–45 degrees.
• Puncture the artery and watch for blood in the hub of the cannula.
• Withdraw the stylet while advancing the cannula slowly.
• There may be spasm from the artery having been touched, hence blood return may be delayed.
• Observe the cannula hub for pulsative blood flow.
• Attach the cannula to the arterial connector and three-way tap and slowly flush with heparinised (one unit of heparin per mL) sodium chloride 0.9%.
• Turn off the three-way tap and secure the cannula with tape and a splint.
• Connect the 10 cm luer-lock, transducer set up and heparinised (one unit of heparin per mL) sodium chloride 0.9% 50 mL syringe.
• Identify the line as an arterial line by placing a red arterial line sticker on the infusion line.
• Observe the fingers/toes for circulation and warmth post procedure.
• Level and zero the pressure transducer if in use and set MEAN alarm limits as per medical preference.
• Secure with splint and strapping. Ensure hub supported/fingers protected by gauze, and that all digits are visible for ongoing assessment.
• Dispose of sharps in sharps bin
• Document blood pressure limits on neonatal fluid balance and treatment orders chart.
• Document procedure in the medical record.

Equipment

The following equipment is needed:

• 2mL syringe
• blood gas syringe +/- syringe for blood collection
• 0.9% sodium chloride
• 2% aqueous chlorhexidine impregnated stick
• antiseptic swab
• IV cap.

Procedure

• Wash hands and prepare work surface.
• Don gloves (non-sterile). Maintain non-touch technique of key sites throughout.
• Turn three-way tap 45 degrees ensuring no port will be open to air. 
• Attach 2 mL syringe to exit port of three-way tap.
• Turn three-way tap off to infusion line and open to neonate and exit port then aspirate blood slowly from the neonate into the syringe. Note: blood pressure monitoring will be interrupted during sampling, alarms may be paused.
• Withdraw into the syringe enough blood to clear the arterial connector line of heparinised (one unit of heparin per mL) sodium chloride 0.9% (2.0 mL is usually sufficient). Retain this syringe, maintain non-touch technique.
• Turn three-way tap to 45 degrees ensuring no port will be open to air.
• Remove syringe from three-way tap and connect blood gas syringe or syringe for blood sample collection.
• Turn three-way tap so that blood can be aspirated from neonate into the syringe.
• Once sufficient blood is collected, turn three-way tap 45 degrees ensuring no port will be open to air.
• Remove this syringe and replace with original syringe of aspirated blood and heparinised (one unit of heparin per mL) sodium chloride 0.9%. Aspirate gently to remove any air from the hub.
• Slowly return the contents of this syringe back to the neonate, observing for signs of arterial spasm such as blanching. Ensure no air is introduced. 

• Turn three-way tap to 45 degrees ensuring no port will be open to air.
• Replace this syringe with 2 mL syringe containing sodium chloride 0.9%.
• Slowly flush the arterial connector and line with sodium chloride 0.9% until the line is cleared of blood.
• Turn three-way tap to 45 degrees ensuring no port will be open to air.
• Insert the 2% aqueous chlorhexidine impregnated stick into the exit port after removing
• Once cleaned, close the port opening with the new IV cap. Turn three-way tap open to infusion of heparinised (one unit of heparin per mL) sodium chloride 0.9% and neonate and closed to the exit port and commence infusion.
• Observe digits and limb for colour, warmth and circulation and record on observation chart.
• Send blood samples as requested.
• Document procedure and investigations on observation chart.

Nursing management

• Careful positioning of the limb with the arterial line in-situ.
• Ensure the tips of the fingers/toes are exposed at all times.
• Observe for adequate patency of artery by ensuring digits and limb are pink, warm and well perfused.
• Inspect and document hourly the area distal and proximal to the insertion site for blanching, redness, cyanosis and changes in temperature and perfusion.
• Report to nurse in charge and medical team if there are changes to circulation of the limb or digits.
• Level and zero arterial line at commencement of every shift and if neonate is turned/moved.
• Heparinised (one unit of heparin per mL) sodium chloride 0.9% only to be administered as a continual infusion at 0.5–1.0 mL/hour.
• Change heparinised (one unit of heparin per mL) sodium chloride 0.9% infusion syringe and minimal extension line every 24 hours, transducer set every third day. 
• Arterial line is only to be used for blood sampling and blood pressure monitoring. Do NOT administer bolus medications or other infusions via this line.

Removal of peripheral arterial line

• Stop the infusion of heparinised sodium chloride.  
• Wash hands and prepare work surface. Don gloves (non-sterile).
• Remove tapes carefully to ensure skin integrity.
• Withdraw the cannula and apply pressure to the site for 5 minutes with a piece of sterile gauze/cotton ball ensuring circulation to the hand/foot is maintained.
• Check to see if the bleeding has stopped. If it has not, apply pressure for a further 2–3 minutes before checking again. Repeat this step as needed.
• Once bleeding has stopped, cover the site with a small piece of gauze and tape/film dressing.
• Observe the digits and limb for adequate circulation and continue to monitor for the next four hours.
• Document procedure in the medical record.

References

Images courtesy of Ballarat Health Service

Government of Western Australia, Women and Newborn Health Service (2016) King Edward Memorial Hospital, Clinical Practice Guidelines, Neonatology: Peripheral arterial catheter insertion and removal

MacDonald, M.G., Ramasethu, J., & Rais-Bahrami, K. (Eds,) (2012) Atlas of procedures in neonatology (5th Ed.) Wolters Kluwer and Lippincott, Williams and Wilkins

Monash Health (2016) Peripheral arterial line insertion and management (neonates) procedure (Intranet only document)

Royal Women’s Hospital, Policy Guideline and Procedure Manual (2014) Arterial catheterisation-peripheral infant (Intranet only document)