Abnormal Pulmonary Gas Exchange

Question 1

Name the four types of abnormal states associated with HYPOXAEMIA

Answer 1

• Ventilation/Perfusion imbalance
• Diffusion impairment
• Alveolar Hypoventilatiom
• Shunt

Question 2

Why is there hypoxaemia in COPD?

Answer 2

• Ventilation perfusion mismatch= Airway obstruction
• Alveolar Hypoventilation=Reduced respiratory drive
• Diffusion Impairment=loss of alveolar surface area (tissue impariment)
• SHUNT- acute infection

Question 3

Why is there hypoxaemia in pnemonia?

Answer 3

Vent- perf= Bronchitis

Shunt= Lobar patterns with large areas of consolidation.

Question 4

What is shunt?

Answer 4

A whole lobe of lung with NO ventilation so all venous blood is deoxygenated.
Normally 2-4%

Question 5

How do you treat large shunts?

Answer 5

Large shunts respond poorly to increase in Fraction inspired O2 Blood leaving normal lung is already 98% saturated.

Question 6

What is alevolar hypoventilation?

Answer 6

Not enough breathes per minute to get rid of co2.

Increases PaCO2

Question 7

What is (hypoxic ) Cor polmonale?

Answer 7

Hypertrophy of the Right Ventricle resulting from disease affecting the functioning and/or the structure of lung.

Question 8

Give an example of cor pulmonale?

Answer 8

Global vasoconstriction in lungs due to high altitude means right ventricle has to work harder and eventually fails.

Question 9

Why do you not treat someone with COPD with O2.

Answer 9

Pateints dont have enough breathes per minute to get rid of CO2.
They loose the Respiratory drive for CO2 and are then dependent on hypoxia.
Only drive to breath is when you dont have enough oxygen (all the time for COPD pateint) so to give oxygen would be to remove respiration drive = BAD