ABG sampling

Question 1

What is an ABG? How is it done?

Answer 1

• ABG is a test for O2 and CO2 levels in blood, as well as acid-base to assess an ill patient.
• Arterial blood is taken from the wrist/groin/inside of elbow
• Allen test should be done beforehand to check that blood flow to the hand is normal.

Question 2

What are the indications for an ABG?

Answer 2

• To obtain & interpret oxygenation levels
• To assess for potential respiratory derangements
• To assess for potential metabolic derangements
• To monitor acid-base status
• To assess carboxyhaemoglobin in CO poisoning
• To assess lactate
• To gain preliminary results for electrolytes and Hb
• Can be conducted as a one off sample or repeated sampling to determine response to interventions

Question 3

What are the contraindications to ABG sampling?

Answer 3

• Local infection
• Distorted anatomy
• Presence of arterio-venous fistulas
• Peripheral vascular disease of the limb to be sampled
• Severe coagulopathy or recent thrombolysis

Question 4

What sampling errors can occur in an ABG?

Answer 4

• Presence of air in the sample
• Collection of venous rather than arterial blood
• An improper quantity of heparin in the syringe, or improper mixing after blood is drawn
• Delay in specimen transportation

Question 5

What are the complications of ABG sampling?

Answer 5

• Haematoma
• Nerve damage
• Arteriospasm or involuntary contraction of the artery
• Aneurysm of artery
• Fainting or a vasovagal response