Procedure: Radial Arterial Line

The Procedure

Circulation – Arterial line insertion (radial)

Today we cover arterial line insertion, with a guide made in partnership with a recent publication in Emergency medicine Australasia. Thanks to Clare Armstrong, Ben Butson and Paul Kwa for their expert input.  

Armstrong C, Butson B, Kwa P. Clinical Procedures: Arterial line insertion. Emergency Medicine Australasia, 2023; 35: 142-7.

Detailed written instructions and explanation are available in our Free App (iOS and Android).

Instructions

Indications

• BLOOD PRESSURE MONITORING
• Haemodynamic instability
• Failed non-invasive monitoring
• Titrating drug therapies or
• FREQUENT ARTERIAL BLOOD SAMPLING

Contraindications (ABSOLUTE/relative)

• PROXIMAL TRAUMATIC INJURY
• Site infection
• Deficient collateral circulation
• Coagulopathy

Alternatives

• Non-invasive BP monitoring
• Femoral arterial line
• Alternative site: Brachial or ulnar, dorsalis pedis, axillary

Consent

• VERBAL – IF HAS CAPACITY
  • Simple procedure with a low risk of complications
• NOT REQUIRED – IF LACKS CAPACITY
  • Emergency procedure to prevent serious injury or death
  • Brief verbal explanation of the procedure is still recommended

Potential complications

• Pain
• Failure
• Minor bleeding or haematoma
• Sampling error (air in sample, venous blood)
• Arterial injury (pseudoaneurysm, arterial dissection, AV fistula)
• Air embolus
• Permanent ischaemic injury (< 0.1%)
• Nerve injury
• Infection (< 1%)

Infection control

• Standard precautions
• PPE: sterile gloves, surgical mask, eye protection, sterile probe cover if using ultrasound,
• Optional PPE: gown, sterile drape

Area

• Resus bay or monitored acute bed

Staff

• Procedural clinician
• Assistant (connection of transducer set and positioning of wrist)

Equipment

ARTERIAL LINE

• Long 20G cannula (24% failure)
• Modified Seldinger guidewire cannula (17% failure)
• Seldinger arterial line set (7% failure)

CHOICE OF ARTERIAL LINE IS GUIDED BY AVAILABILITY, PERSONAL PREFERENCE AND SKILL SET

• Rolled towel and tape (arm positioning)
• Ultrasound + sterile probe cover and gel
• 25G needle + 5ml syringe (anaesthetic)
• Fluid giving set primed with saline
• 500ml or 1000ml of sterile 0.9% sodium chloride in pressure bag at 300mmHg
• Transducer set
• Arm board
• Non-injectable cap
• Suture or Steri-Strips
• Transparent adhesive dressing
• 3ml blood gas syringe

Positioning

• Pt Supine
• Arm extended
• Rolled towel under wrist
• 45-degree wrist extension
• Hand and wrist immobilised  (assistant or tape) 

TAPE CAN BE USED AROUND THE THUMB OR ALL THE WHOLE HAND AND IS OFTEN SECURES TO THE BED RAIL. TAKING TIME TO OPTIMISE THE POSITION IS RECOMMENDED

Medication

• 1-2ml lignocaine 1%

Sequence (Insertion)

WE RECOMMEND INSERTION UNDER ULTRASOUND GUIDANCE. ULTRASOUND GUIDANCE HAS BEEN SHOWN TO REDUCE FAILURE RATES AND COMPLICATIONS. ALWAYS USE A STERILE PROBE COVER WHEN INSERTING LINES UNDER ULTRASOUND GUIDANCE. 

• Prime the measure set with 0.9% Saline and inflate the pressure bag to 300 mmHg and flush top removal all bubbles
• Position transducer at the level of the heart, approximately 5 cm below the sternum in the supine patient.
• Locate the radial artery with ultrasound.
• Local anaesthetic infiltration
• Wait 1 minute, then massage bleb of anaesthetic with gauze to disperse and restore anatomy
• Ensure transducer set is ready, with fluid giving set primed under pressure prior to line insertion
• Insert finding needle 10-20 degrees to skin with the bevel down
• Advance the needle under direct ultrasound guidance (in-plane or out-of-plane)
• Obtain arterial flashback then advance a further 1-2mm to ensure needle lumen is entirely in the vessel
• Perform Seldinger technique or cannulate vessel
• Pulsatile flow of blood confirms position in vessel
• Firmly occlude artery at level just proximal to tip of arterial line when removing wire and connecting to transducer set.
• Secure line and dress insertion site (suture if difficulty access or difficult to secure)
• Arm board to hold wrist in extension

Sequence (Set up)

• Position transducer at the level of the heart, approximately 5 cm below the sternum in the supine patient.
• Connect transducer set to giving set under pressure and prime with flush device to remove all air bubbles
• Connect transducer cable to monitor
• Calibrate: set off to patient and open to air then press ‘Zero’ on monitor
• Calibrate: when ‘0’ on screen, set open to patient and transducer, off to air
• Secure line and dress insertion site (suture if difficulty access or difficult to secure)
• Arm board to hold wrist in extension

Sequence (Sampling)

• Remove cap from sampling port and attach a 5ml syringe
• Turn three-way tap so the arterial line is open from the patient to the sampling port
• Attach 5ml syringe to the sampling port and aspirate 2-5ml to ensure the line is clear of saline
• Turn the three-way tap so the arterial line is closed from the patient to the sampling port
• Remove the 5ml syringe and discard
• Attach blood gas syringe to the sampling port
• Turn three-way tap so the arterial line is open from the patient to the sampling port and allow syringe to fill
• Gentle aspirate if passive filling is slow
• Turn three-way tap so the arterial line is closed from the patient to the sampling port
• Remove the blood gas syringe from the sampling port
• Turn the three-way tap so the arterial line is open from the patient to the flush device
• Press the flush device together or pull the toggle to flush the line
• Turn the three-way tap so the arterial line is open from the flush device to the sampling port
• Flush again into sterile gauze swab to ensure all air is expelled from the system
• Turn the three-way tap so it is open to the patient and the transducer
• Check there is an arterial waveform on the monitor
• Place a new red non-injectable bung on the sampling port

Post-procedure care

• Limb neurovascular observations (pulse, colour, temperature, sensation, and cap refill)
• Document insertion site, attempts, guidewire removal (if used) and any immediate complications

Tips

• Use your needle with the bevel down,  increase success by as much as 10%
• The radial artery is the preferred site due to accessibility and collateral circulation
• The second option is a femoral arterial line, with brachial as a third option
• If a catheter fails to thread it has not entered the lumen and should not be forced to advance
• Ultrasound can significantly improve first attempt success rate

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Discussion

First pass success is important. Failed attempts cause vasospasm and haematomas reducing the chances of later success. There is strong evidence for improving success by:

• Using a cannula set which incorporates a guidewire
• Always using ultrasound
• Using a shallow insertion angle
• Using your needle bevel up

Using a Seldinger method of arterial line insertions reduced failure. Simple cannula methods have a failure rate of 24%. Using an integral guidewire set reduced failure rates to 17%. Using a full Seldinger set with a separate guidewire reduces failure rates to 7%.

Ultrasound is proven to increase success and reduce complication. When using ultrasound, a shallow insertion angle greatly enhances needle visualisation by increasing sound wave reflection. This is the single biggest ultrasound factor that will improve your view of the needle. The next biggest factor is bevel orientation. Inserting your needle Bevel up will aid sound reflection and ultrasound visualisation of the needle tip and reduced posterior wall puncture. In experienced hands, success rates are also higher with an in-plane insertion technique.

The radial artery is the usual preferred insertion site due to accessibility, collateral blood supply and low complication rates. Other sites in decreasing order of preference include the femoral, ulnar, brachial, dorsalis pedis, axillary and posterior tibial arteries. Femoral lines may be the best option in difficult cases due to lower rates of insertion failure (5% compared to 30%).

The use of the Allen’s test prior to radial artery cannulation is no longer recommended and has been shown to be unreliable at predicting the presence of collateral circulation or risk of complications.

Local anaesthetic is recommended for all arterial line insertions. Multiple studies show subjective improvement in pain. A more comfortable patient is likely to reduce clinician stress and patient movement improving success rate. Lignocaine may also reduce the incidence of arterial vasospasm improving the size of the target vessel.

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References

• Armstrong C, Butson B, Kwa P. Arterial line insertion. Emerg Med Australas. 2023 Feb;35(1):142-147
• Melhuish TM, White LD. Optimal wrist positioning for radial arterial cannulation in adults: A systematic review and meta-analysis. Am J Emerg Med. 2016 Dec;34(12):2372-2378.
• White L, Halpin A, Turner M, Wallace L. Ultrasound-guided radial artery cannulation in adult and paediatric populations: a systematic review and meta-analysis. Br J Anaesth. 2016 May;116(5):610-7.
• Saugel B, Kouz K, Meidert AS, Schulte-Uentrop L, Romagnoli S. How to measure blood pressure using an arterial catheter: a systematic 5-step approach. Crit Care. 2020 Apr 24;24(1):172.
• Cho SA, Jang YE, Ji SH, Kim EH, Lee JH, Kim HS, Kim JT. Ultrasound-guided arterial catheterization. Anesth Pain Med (Seoul). 2021 Apr;16(2):119-132.
• Min SW, Cho HR, Jeon YT, Oh AY, Park HP, Yang CW, Choi WH, Kim BG. Effect of bevel direction on the success rate of ultrasound-guided radial arterial catheterization. BMC Anesthesiol. 2016 Jul 11;16(1):34.
• Berk D, Gurkan Y, Kus A, Ulugol H, Solak M, Toker K. Ultrasound-guided radial arterial cannulation: long axis/in-plane versus short axis/out-of-plane approaches? J Clin Monit Comput. 2013 Jun;27(3):319-24.
• Tatlı E, Yılmaztepe MA, Vural MG, Tokatlı A, Aksoy M, Ağaç MT, Çakar MA, Gündüz H, Akdemir R. Cutaneous analgesia before transradial access for coronary intervention to prevent radial artery spasm. Perfusion. 2018 Mar;33(2):110-114
• Lim T, Ryu HG, Jung CW, Jeon Y, Bahk JH. Effect of the bevel direction of puncture needle on success rate and complications during internal jugular vein catheterization. Crit Care Med. 2012 Feb;40(2):491-4.
• Dinges HC, Hoeft J, Cornelius VM, Steinfeldt T, Wiesmann T, Wulf H, Schubert AK. Nominal logistic regression analysis of variables determining needle visibility in ultrasound images – a full factorial cadaver study. BMC Anesthesiol. 2023 Nov 10;23(1):369.
• Gálvez JA, Lin EE, Schwartz AJ, Simpao AF. Ultrasound-guided Vascular Access: Visualizing the Tip of the Needle. Anesthesiology. 2016 Aug;125(2):396.

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