• ensure you do not rush
• adopt adequate positioning so you and the patient is comfortable
• have plenty of lighting
• have ensured your equipment looks to be working
• that you have access to an ABG machine (including a code if need be)

Procedure

1. Introductions, consent, hand washing
2. Consider whether a VBG would answer your question. ABGs are best kept to a minimum
3. Check if the patient is on oxygen and their temperature. This will affect the readings.  
4. Allen’s test (assessing ulnar artery patency). It is frequently not done in clinical practice for radial sampling due to the very good collateral supply to the hand and questionable reliability of the test according to UpToDate
. However, an abnormal Allen’s test is a contraindication to radial artery sampling.
5. Position the patient’s wrist in supination and extension with a pillow under the wrist.
7. Clean the wrist with an alcohol swab and allow to dry
8. [Given how painful arterial sampling can be, some doctors elect to infiltrate with some local anaesthetic]
9. Attach the needle to the syringe and depress the plunger to allow heparin to fully coat. If the syringe is self-filling, retract the plunger back to the 1-2mls marker on the syringe to allow this volume to self-fill when the artery is accessed.
10. Palpate radial artery (with non-dominant hand). Feel for the strongest part of the pulse and place your fingers either side
11. Once the radial pulse is identified, warn the patient and, holding the needle like a pen, insert it at a roughly 30-degree angle until you see the flash of arterial blood in the needle
12. Either allow the syringe to self-fill or withdraw on the plunger, depending on the ABG sampling syringe used. 1-2mls of sample should be obtained 
13. Remove the needle and apply direct and firm pressure onto the puncture site with gauze for 5 minutes (can get the patient to do this!)
14. Remove the needle and replace with the cap, disposing the needle in the sharps bin
15. Expel any air bubble and ensure the sample is kept moving while you get to the analyser (within 10 minutes max but ideally straight away as the red cells continue to metabolise)

By Dr Amina Aslam (FY2)
Video created by Dr Cesci Adams, Dr Michaela Gaston, Dr Siona Sabu (Clinical Teaching Fellows)
Visual summary created by Dr Brian Ng (FY3)