ABG

Question 1

What is the introduction for ABG?

Answer 1

Wash hands

Introduce yourself

Confirm patient details:

Name / date of birth

-Take note of whether the patient is requiring oxygen and record how much (e.g. FiO2 concentration or flow rate)

Check for any contraindications to ABG sampling:

Absolute –  poor collateral circulation / peripheral vascular disease in the limb / cellulitis surrounding the site / arteriovenous fistula
Relative – impaired coagulation (e.g. anticoagulation therapy / liver disease / low platelets <50)

Explain procedure:

“I need to take a sample of blood from an artery in the wrist to assess the oxygen levels in your circulation. It will be a little painful, but should hopefully only take a short amount of time. The procedure does involve some risks which include bleeding, bruising, infection and permanent damage to the artery.”

Gain consent:

“Do you understand everything I’ve said so far? Are you happy for me to go ahead?”

Question 2

What must you do after your introduction BEFORE even getting the ABG equipment?

Answer 2

Modified Allens test:
This test involves the assessment of the arterial supply to the hand.

1. Ask the patient to clench their fist
2. Apply pressure over both the radial and ulnar artery to obstruct blood supply to the hand
3. Ask the patient to open their hand, which should now appear blanched (if not you have not completely occluded the arteries with your fingers)
4. Remove pressure from the ulnar artery whilst maintaining pressure over the radial artery
5. If there is adequate blood supply from the ulnar artery, colour should return to the entire hand within 5-15 seconds

It should be noted that there is no evidence performing this test reduces the rate of ischaemic complications of arterial sampling.

Question 3

How do you prepare to take the ABG sample?

Answer 3

1. Position the patient’s arm preferably on a pillow for comfort with the wrist extended (20-30°)
2. Prepare all the equipment in the equipment tray using an aseptic non touch technique
3. Palpate the radial artery on the patient’s non-dominant hand (most pulsatile over the lateral anterior aspect of the wrist)
4. Clean the site with an alcohol wipe for 30 seconds and allow to dry before proceeding
5. Wash hands again
6. Don gloves and apron
7. Prepare and administer lidocaine subcutaneously over the planned puncture site (aspirate to ensure you are not in a blood vessel before injecting the local anaesthetic).
8. Allow at least 60 seconds for the local anesthetic to work
9. Attach the needle to the ABG syringe, expel the heparin and pull the syringe plunger to the required fill level (check with your local laboratory)

Question 4

How do you take an ABG sample?

Answer 4

1. Palpate the radial artery with your non-dominant hand’s index finger around 1cm proximal to the planned puncture site (avoiding directly touching the planned puncture site that you have just cleaned)
2. Warn the patient you are going to insert the needle
3. Holding the ABG syringe like a dart insert the ABG needle through the skin at an angle of 45° over the point of maximal radial artery pulsation (which you identified during palpation)
4. Advance the needle into the radial artery until you observe blood flashback into the ABG syringe
5. The syringe should then begin to self-fill in a pulsatile manner (do not pull back the syringe plunger)
6. Once the required amount of blood has been collected remove the needle and apply immediate firm pressure over the puncture site with some gauze
7. Engage the needle safety guard
8. Remove the ABG needle from the syringe and discard safely into a sharps bin
9. Place a cap onto the ABG syringe and label the sample
10. Yourself or a colleague should continue to apply firm pressure for 3-5 minutes to reduce the risk of haematoma formation