ABG

Question 1

Why perform an ABG?

Answer 1

Assess respiratory function,
Hypoxia,
Hypercapnia

Question 2

What is the normal pH of arterial plasma?

Answer 2

7.36-7.44

Question 3

What are the levels of H, HCO3 and CO2 in metabolically acidosis?

Answer 3

High hydrogen ions,
Low HCO3,
Low C02 (compensation)

Question 4

What are the levels of H, HCO3 and CO2 in metabolically alkalosis?

Answer 4

Low hydrogen ions,
High HCO3,
High CO2 (compensation)

Question 5

What are the levels of H, HCO3 and CO2 in respiratory acidosis?

Answer 5

High hydrogen ions,
High CO2,
High HCO3 (compensation)

Question 6

What are the levels of H, HCO3 and CO2 in respiratory alkalosis?

Answer 6

Low hydrogen ions,
Low CO2,
Low HCO3 (compensation)

Question 7

Causes of metabolic acidosis? (h: KUSSSMAAUL)

Answer 7

Ketoacidosis, 
Uraemia, 
Salicylate/ Paractamol poisoning
Starvation
Severe HCO3 loss (GI fistula, diarrhoea)
Methanol
Aethylene glycol
Alcohol, 
U
Lactic Acidosis

Question 8

Causes of metabolic alkalosis? (6)

Answer 8

Loss of acid- vomiting,
Loss of potassium- excess diuretic drugs,
Hyperaldosteronism,
Cushings, 
Liquorice, 
Excess alkaline ingestion

Question 9

Causes of respiratory acidosis? (7)

Answer 9

Severe acute asthma, 
Severe pneumonia, 
Exacerbation of COPD, 
Neuromuscular disorders, 
CNS "depression",
Reduced consciousness levels,
Chocking

Question 10

Causes of respiratory alkalosis? (3)

Answer 10

Hyperventilation,
CNS “irritation”:
-Raised ICP,
-Salicylate poisoning

Question 11

What is the overall simple cause for respiratory acidosis?

Answer 11

The inability to blow off CO2

Question 12

How long does it take the renal system to compensate for respiratory acidosis?

Answer 12

48-72 hours

Question 13

What is the overall simple cause for respiratory alkalosis?

Answer 13

Blowing off more CO2

Question 14

What is the overall simple cause for metabolic acidosis?

Answer 14

Impaired H+ excretion or
Increased H+ production or ingestion or
Loss of HCO3

Question 15

What is the overall simple cause for metabolic alkalosis?

Answer 15

Decrease in H+ or

Increase in HCO3-

Question 16

What is the equation for the anion gap?

Answer 16

[Na+ + K+] - [Cl- + HCO3-]

Question 17

Normal anion gap range?

Answer 17

14-18

Question 18

Causes for metabolic acidosis with normal anion gap? (3)

Answer 18

Chronic diarrhoea,
Intestinal fistula,
Renal tubular acidosis

Question 19

Causes for metabolic acidosis with increased anion gap? (3)

Answer 19

Renal disease, 
DKA, 
Lactic acidosis:
-Severe hypoxia, 
-Severe anaemia
-Shock
-Haemorrhage
-Hypotension
-Congestive cardiac failure
-Liver failure
-Seizures
-Thiamine deficiency
Poisoning:
-Ethanol/ methanol/ ethylene glycol/ salicylate