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11/13/24, 7\:18 PM Guide | Arterial blood gas (ABG) sampling

Arterial blood gas (ABG) sampling

Table of contents
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Gather equipment

Gather the appropriate equipment\:
Gloves
Apron
Pre-heparinised arterial blood gas syringe and bung or cap
Arterial blood gas needle (23 G)
Alcohol wipe (70% isopropyl)
Gauze or cotton wool
Tape
Lidocaine 1% (1 mL)
Subcutaneous needle (25-27 G)
Small syringe for lidocaine (1-2 ml)
Sharps container
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Gather equipment

Introduction

Wash your hands and don PPE if appropriate.
Introduce yourself to the patient including your name and role.
Con
Brie
a r t e r y i n y o u r w r i s t t o a c c u r a t e l y a s s e s s y o u r o x y g e n l e v e l s . T h e p r o c e d u r e w i l l b e a l i t t l e p a i n f u l , h o w e v e r , i t s h o u l d o n l y t a k e a
s h o r t a m o u n t o f t i m e . I f y o u w a n t m e t o s t o p a t a n y p o i n t , j u s t l e t m e k n o w . T h e p r o c e d u r e d o e s i n v o l v e s o m e r i s k s w h i c h
i n c l u d e b l e e d i n g , b r u i s i n g , i n f e c t i o n a n d v e r y r a r e l y p e r m a n e n t d a m a ge t o t h e a r t e r y b e i n g s a m p l e d f r o m .
"
Check for any contraindications to arterial blood gas sampling\:
Absolute contraindications\: peripheral vascular disease in the limb, cellulitis surrounding the site or arteriovenous
Relative contraindications\: impaired coagulation (e.g. anticoagulation therapy, liver disease, low platelets \<50).
Check if the patient has an allergy to local anaesthetic (e.g. lidocaine).
Gain consent to proceed with arterial blood gas sampling.
Adequately expose the patient's wrist for the procedure.
Position the patient so that they are sitting comfortably, ideally with their wrist supported by a pillow. If a bed is available, the
patient can lay down for the procedure (this is sometimes preferable, particularly if the patient is prone to vasovagal syncope).
Ask the patient if they have any pain before continuing with the clinical procedure.
How oxygen therapy impacts ABG results
PaO 2
should be greater than 10 kPa when oxygenating on room air in a healthy patient.
If the patient is receiving oxygen therapy their PaO 2
should be approximately 10kPa less than the % inspired
concentration FiO 2 2
(so a patient on 40% oxygen would be expected to have a PaO of approximately 30kPa).
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Modi

Before taking a sample from the radial artery, a modi
supply of the hand from the ulnar artery. The idea behind this assessment is to make sure the patient's hand isn't exclusively
reliant on the radial artery for its blood supply, in which case sampling should be avoided.
To perform a modi
1. Ask the patient to clench their
2. Apply pressure over the radial and ulnar artery to occlude both vessels.
3. Ask the patient to open their hand, which should now appear blanched. If the hand does not appear it suggests you are not
completely occluding the arteries with your
4. Remove the pressure from the ulnar artery whilst maintaining pressure over the radial artery.
5. If there is adequate blood supply from the ulnar artery, the normal colour should return to the entire hand within 5-15
seconds. If the return of colour takes longer, this suggests poor collateral circulation Do not perform arterial blood gas
sampling on a hand that does not appear to have an adequate collateral blood supply.
It should be noted that there is no evidence performing this test reduces the rate of ischaemic complications of arterial
sampling.
Ask the patient to clench their

Preparation

Oxygen and body temperature

Note the patient's body temperature and if the patient is currently receiving oxygen therapy, note the oxygen delivery device
and
These factors can signi

Equipment

Remove all equipment from its packaging so that it is easily accessible during the procedure.
Attach the needle, with its protective cover intact, to the pre-heparinised ABG syringe.
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Positioning

Position the patient's hand preferably on a pillow for comfort with the wrist extended by approximately 20-30°
.

Procedure

Palpation

Assess the course of the radial artery to determine where you plan to perform arterial sampling\:
1. Palpate the radial artery over the wrist of the patient's non-dominant hand to identify an ideal puncture site. You should use
the tips of your
pulsatile. The radial artery is typically most super
2. Once you have identi
proceeding.
3. Wash your hands again.
4. Don a pair of gloves and an apron.
Palpate and assess the course of the radial artery

Local anaesthetic

Pain associated with arterial blood gas sampling can be markedly reduced by the use of subcutaneous local anaesthetic. The
British Thoracic Society recommends the routine use of local anaesthetic for obtaining ABG samples except in the context of an
emergency or if the patient is unconscious.
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). See our guide to subcutaneous injection for more details.
Allow at least 60 seconds for the local anaesthetic to work.

Arterial puncture

1. Remove the protective cover from the ABG needle and then
2. Hold the patient's wrist extended by approximately 20-30°
.
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3. Palpate the radial artery with your non-dominant hand's index
(avoiding contaminating the planned puncture site that you previously cleaned).
4. Warn the patient you are going to insert the needle.
5. Holding the ABG syringe like a dart, insert the needle through the skin at the insertion site at an angle of 30-45°
.
6. Continue to advance the needle slowly towards the pulsation until you feel a sudden reduction in resistance and see a rush
of blood back into the ABG syringe (this is known as "
7. The ABG syringe should then begin to self-
through or missed the artery and therefore need to re-adjust your position based on your understanding of the course of the
radial artery (e.g. change in angulation or slight withdrawal of the needle).
8. Once the required amount of blood has been collected, remove the needle and apply immediate
puncture site with some gauze. Secure the gauze with some tape and continue to apply pressure.
9. Engage the needle safety device (often a clip that covers the needle or a bung that the needle is inserted into).
10. Remove the ABG needle from the syringe and discard it immediately into a sharps bin.
11. Carefully expel any air from the sample if present, place a cap onto the ABG syringe and invert it gently.
12. Attach a sticker containing the patient's details to the ABG sample.
13. Continue to apply
Flush heparin through the needle
ABG reference ranges
pH\: 7.35 – 7.45
PaCO \: 4.7 – 6.0 kPa || 35.2 – 45 mmHg
2
PaO \: 11 – 13 kPa || 82.5 – 97.5 mmHg
2
HCO –\: 22 – 26 mEq/L
3
Base excess (BE)\: -2 to +2 mmol/L
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To complete the procedure...

Explain to the patient that the procedure is now complete.
Thank the patient for their time.
Dispose of your PPE and equipment into an appropriate clinical waste bin.
Wash your hands.
Take the ABG sample to be analysed as soon as possible after being taken as delays longer than 10 minutes can a
accuracy of results.
Document the ABG results in the patient's notes (see our guide to ABG documentation).

References

Source\: geekymedics.com
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