This document provides an overview and instructions for performing an arterial blood gas (ABG) test. It outlines the necessary equipment, including phlebotomy supplies and blood gas syringes. It describes how to prepare the patient, including performing Allen's test to check ulnar artery flow. The procedure steps are explained in detail, from locating the radial artery to withdrawing blood and applying pressure. Common indications for ABG tests and reminders to avoid complications like hematomas are reviewed. Frequently asked questions are answered concerning alternative sites if the radial artery cannot be palpated and whether full syringe samples are needed.

1. INTERN SURVIVAL GUIDE
Arterial Blood Gas

2. Tutorial Overview
• Equipment Selection
• Equipment & Patient Preparation & Allen’s Test
• Procedure Steps
• Indications
• Reminders & FAQs

3. Equipment Selection
1. Phlebotomy tray and
sharps Bucket
1. Phlebotomy tray and
sharps Bucket
2. Non-sterile gloves2. Non-sterile gloves 3. Alcohol swabs
6. Rolled up towel
3. Alcohol swabs
6. Rolled up towel4. Blood gas syringes4. Blood gas syringes 5. Cotton buds and tape5. Cotton buds and tape

4. At Bedside: Equipment
Preparation
• Hand hygiene
• Open the alcohol swab
by tearing along the top
of it
• Open the ABG bottle
packaging and assemble
the syringe
• Do not throw away the
black cap

5. At Bedside: Patient Preparation
Allen’s Test
• To assess adequacy of ulnar
collateral flow
1. Patient elevates their hand
2. Patient clenches fist several
times to blanch palmar skin
3. Firm occlusive pressure applied
on both radial and ulnar artery
4. Release ulnar artery while the
radial artery is compressed
5. Observe for palmar reperfusion
6. Repeat the test with radial artery
release first

6. At Bedside: Patient Preparation
1. Perform hand hygiene
2. Position hand on a firm surface with wrist
in 40°extension
3. Place rolled towel under wrist for comfort
4. Palpate brachial artery with middle and
index finger. Make sure you can palpate it
with a gloved hand
5. Mark point where you can feel the pulse
in between your 2 fingers with a skin
marker and clean with alcohol swab

7. Procedure Steps
1. Open and uncap ABG needle
2. Palpate the vessel again between your 2
fingers
3. Face bevel towards heart, insert between
60°and 90°between fingers
4. Advance needle until arterial blood starts to
fill syringe. There is no need to withdraw
plunger. This should be very superficial
5. Fill 2 - 2.5ml
6. Simultaneously withdraw needs and place
cotton bud over puncture site. Apply pressure
immediately
7. Instruct patient to apply pressure for 5
minutes

8. Procedure Steps
8. Dispose of needle
9. Expel air from syringe and apply black
safety cap
10. Mix sample by rolling between hands
11. Label bottles and confirm patient
identity at bedside
12. Check and redress puncture site after
5 minutes
13. Dispose of clinical waste and perform
hand hygiene
14. Record procedure in patient notes

9. ABG Indications
• Identification of acid-base disorders
• Monitoring of acid-base status
• Measurement of arterial CO2
• Monitoring of ventilated patients
• Assessment of respiratory failure
• Remember that you can get additional information:
electrolytes, haemoglobin, lactate

10. Reminders
• Haematoma
– To avoid this puncture only the uppermost wall of the artery by advancing the
needle slowly into the artery
– Do not perform on patients with a severe coagulopathy and caution should be
exercised in patients on warfarin or heparin
– Apply pressure to the site immediately after puncture and advise the patient
to maintain pressure for 5 minutes
• Vessel Damage / Occlusion
– Perform Allen’s test to ensure patency of ulnar artery. To avoid artery
damage, insert needle as close to 90°as possible
• Pain
– ABG sampling can be painful if the needle penetrates deep and touches the
periosteum of the radial styloid
– To avoid this, remember that the radial artery is superficial at the wrist and
advance the needle slowly and wait for the syringe to fill

11. Frequently Asked Questions
• What happens if I can not palpate the radial artery?
– Try the other wrist. You may have to use the brachial
artery or the femoral artery. As an intern you should only
do this under supervision and knowing the anatomy of the
regions
• Is aspirin a contraindication to ABG?
– No. Remember to apply pressure and observe for bleeding
• Is severe peripheral vascular disease a contraindication
to ABG
– Yes

12. Frequently Asked Questions
• What to do if Allen’s test is abnormal?
– Document your findings in the patient’s chart and try the other
radial artery. Otherwise get senior help
• Does the syringe need to be fully filled?
– No. 2 -2.5mls is sufficient. The ABG machine requires between
0.5 and 1 ml to process a sample. Remember that you will have
to expel air from the sample and you may need to reprocess the
sample so it is a good idea to keep the sample until the machine
has printed the result
• Do I need to remove supplemental oxygen from a patient
to perform an ABG?
– No, do not remove the oxygen. Remember to record the
patient’s name, ID and percentage O2 on the result

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