Arterial blood gas

Question 0

ABG findings in acute type 1 respiratory failure

Answer 0

pH: 7.49 (alkilotic) 
p02: 8kPa (hypoxia)
pC02: 4kPa (hypocapnic)
HCO3: 22 (borderline bicarbonate)
Here the pt is tachypnoeic to get more O2, which is blowing off the CO2 causing an alkalosis --> eg PE or pneumothorax

Question 1

Normal ABG findings

Answer 1

pH: 7.35-7.45
p02: >10.5kPa
pC02: 4.5-6kPa
HCO3: 22-28

Question 2

ABG findings in chronic type 1 respiratory failure

Answer 2

pH: 7.41 (normal)
p02: 9kPa (hypoxia)
pC02: 4.8kPa (normal)
HCO3: 24 (normal bicarbonate)
This is a chronic state so there is no increased respiratory drive despite hypoxia, and acid/base is normal--> pulmonary fibrosis

Question 3

ABG Findings in simple hyperventilation

Answer 3

pH: 7.55 (alkilotic)
p02: 15kPa (hyperoxia)
pC02: 3kPa (hypocapnic)
HCO3: 18 (low bicarbonate)
Here there is respiratory alkalosis but without any underlying hypoxia --> simple hyperventilation

Question 4

ABG findings in type II respiratory failure

Answer 4

pH: 7.29 (acidotic)
p02: 7.3kPa (hypoxia)
pC02: 7kPa (hypercapnic)
HCO3: 30 (high bicarbonate)
This is a acute exacerbation causing hypoxia on the background of a chronic p, compensated respiratory acidosis due to CO2 retention --> thus the high bicarbonate

Question 5

ABG findings of chronic type II respiratory failure

Answer 5

pH: 7.37 (normal)
p02: 7.9kPa (hypoxia)
pC02: 6.9kPa (hypercapnic)
HCO3: 33 (high bicarbonate)
This shows a hypercapnic hypoxia but with high bicarbonate, this normal pH, indicating it is a chronic compensated condition --> stable CO2 retaining COPD

Question 6

ABG findings in acute acidotic respiratory failure

Answer 6

pH: 7.33 (acidotic)
p02: 7.5kPa (hypoxia)
pC02: 6.1kPa (hypercapnic)
HCO3: 22 (normal bicarbonate)
This is an acute (non-compensated, normal HCO3) type II respiratory failure causing acidosis --> multiple causes but there is a failure of ventilation leading to high CO2