Case 12: Breathless

Front 1

Name 4 respiratory courses of hypoxia.

Back 1

Hypoventilation

Impaired diffusion

Shunt (blood diverted: artery -> vein, or vice versa)

V/Q mismatch

Front 2

Name 3 non-respiratory courses of hypoxia.

Back 2

Intracardiac R->L shunt

Reduced inspired O2

Reduced O2 content (e.g. anaemia)

Front 3

Define Type 1 respiratory failure

Name 3 causes of this

Back 3

PaO2 is low (hypoxia); PaCO2 is low or normal

Causes:

V/Q mismatch (asthma, COPD, pulmonary embolism)

R->L Shunt (intra-pulmonary Arteriovenous Malformations, lobar consolidation due to pneumonia, extrapulmonary cardiac defects)

Impaired diffusion (e.g. in oedema, interstitial lung disease, emphysema, etc.)

Front 4

Regulation of inspiration:
What part of brain fine-tunes medulla action?

Back 4

The pons, via

Pneumotaxic centre
(switches off DRG)
(limits duration of inspiration)

Apneustic centre
(inhibits switching-off of DRG)
(prolongs duration of inspiration)

Front 5

Regulation of inspiration:
What role is the medulla oblongata?

Back 5

Pace-maker centre for respiration

Front 6

Regulation of inspiration:
What are the respiratory centres of the medulla oblongata?

Back 6

Pre-Botzinger Complex
- Assumed to be pace-maker

Dorsal respiratory group (DRG)
- Mostly inspiratory
- Basic rhythm of respiration

Ventral respiratory group (VRG)
- Mostly expiratory
- Also some inspiratory activity
- Inactive in quiet breathing
- Recruited when ^ ventilation required