Type 1 & 2 respiratory failure

Question 1

What can be found in the carotid arteries which respond to levels of carbon dioxide and oxygen?

Answer 1

Chemoreceptors

Question 2

What is the main drive of respiratory function?

Answer 2

Presence of acidemia in the medulla

Question 3

Respiratory failure if defined as arterial pO2 below what level?

Answer 3

<8kPa

Question 4

What are the differences between type 1 and type 2 respiratory failure?

Answer 4

Type 1: low oxygen associated with a normal or low pCO2 and HCO3 is normal

Type 2: low oxygen associated with raised CO2, HCO3 normal if acute or high if chronic

Question 5

What are some causes of respiratory failure?

Answer 5

Low oxygen delivery: high altitude
Airway obstruction: asthma, COPD
Gas exchange or diffusion limitation: lung fibrosis or asbestosis
Ventilation/perfusion mismatch: pneumonia, pulmonary embolism, pulmonary hypertension
Alveolar hypoventilation: emphysema, muscular weakness (MND), reduced respiratory drive (opiate drugs), obesity

Question 6

Causes of academia (3)

Answer 6

1. CO2 production (ventilatory failure)
2. Loss of HCO3 - (salicylate poisoning)
3. Increase in H+ production (ketoacidosis)

Question 7

Describe what happens during nighttime ventilation and how sleep apnoea can occur.
How is sleep apnoea managed?

Answer 7

In night time ventilation, there is compression of the soft palate. Normally, this shouldn’t cause any problems but in patients with enlarged adenoids or excess soft tissue around their neck, there is an increase in compression around the airway. This can cause breathing difficulties during sleep (partner usually notices)

Management: CPAP (continuous positive airway pressure) machine to assist with breathing.

Question 8

Difference between CPAP and BiPAP?

Answer 8

CPAP: continuous pressure supply to the upper airways
BiPAP: not continuous, BiPAP machines have two pressure settings: one pressure for inhalation (IPAP), and a lower pressure for exhalation (EPAP)

Question 9

Things such as severe pneumonia, pulmonary embolism, acute asthma, pulmonary fibrosis will cause type 1 or type 2 respiratory failure?

Answer 9

Type 1 - ventilation perfusion mismatch in areas of the lung. Increased ventilation removes excess CO2 but cannot compensate for low pO2

Question 10

Things such as COPD, NM disorders, obesity hypoventilation syndrome will cause type 1 or type 2 respiratory failure?

Answer 10

Type 2 - generalised alveolar hypoventilation. Transfer of both O2 and CO2 is impaired so pCO2 is raised in addition to low pO2

Question 11

Does acute respiratory failure more commonly develop in an otherwise healthy patient or those with chronic lung diseases?

Answer 11

Otherwise healthy patients - there is obvious respiratory distress with hyperventilation

Question 12

Does chronic respiratory failure more commonly develop in an otherwise healthy patient or those with chronic lung diseases?

Answer 12

More persistent problem in those with chronic lung diseases - the clinical picture may be surprisingly undramatic despite the low pO2 due to compensatory mechanisms