Respiratory Failure

Question 1

Type 1 respiratory failure

Answer 1

Hypoxaemia (PaO2 <8 kPa / 60mmHg) with normocapnia (PaCO2 <6.0 kPa / 45mmHg)

Question 2

Type 2 respiratory failure

Answer 2

Hypoxaemia (PaO2 <8 kPa / 60mmHg) with hypercapnia (PaCO2 >6.0 kPa / 45mmHg)

Question 3

Why does type 1 respiratory failure occur?

Answer 3

Ventilation/perfusion (V/Q) mismatch

The volume of air flowing in and out of the lungs is not matched with the flow of blood to the lung tissue

Question 4

Examples of V/Q mismatch

Answer 4

Reduced ventilation and normal perfusion (e.g. pulmonary oedema, bronchoconstriction)

Reduced perfusion with normal ventilation (e.g. pulmonary embolism)

Question 5

Why does type 2 respiratory failure occur?

Answer 5

Alveolar hypoventilation

Prevents patient from being able to adequately oxygenate and eliminate CO2 from their blood

Question 6

How does hypoventilation occur?

Answer 6

Increased resistance as a result of airway obstruction (e.g. COPD)

Reduced compliance of lung tissue/chest wall (e.g. pneumonia, rib fractures, obesity)

Reduced strength of respiratory muscles (e.g. Guillain-Barré, motor neurone disease)

Drugs acting on the respiratory centre reducing overall ventilation (e.g. opiates)

Question 7

What type of NIVis used in type 2 respiratory failure?

Answer 7

BiPAP