Pathology of Respiratory Tract infections 2 Flashcards
What are the 4 abnormal states associated with hypoxaemia
Ventilation / Perfusion imbalance - V/Q
Diffusion impairment
Alveolar Hypoventilation
Shunt – no ventilation of abnormal alveoli
When does physiological pulmonary arteriolar vasoconstriction occur
When oxygen tension falls
What happens when physiological pulmonary arteriolar vasoconstriction is acting as a localised effect
It causes all the vessels to constrict if there is arterial hypoxaemia.
It is a protective mechanism that prevents blood from being sent to alveoli which are short of oxygen
Where can ventilation/perfusion imbalance be seen
Bronchitis/bronchopneumonia
What occurs in the ventilation/perfusion imbalance seen in bronchitis/bronchopneumonia
Some ventilation of abnormal alveoli
Shunt seen in severe bronchopneumonia producing a lobar pattern with large areas of consolidation
How much is breathed normally per minute
4L
What is a normal cardiac output per minute
5L
What is normal V/Q
4/5 so 0.8
What is the commonest cause of hypoxaemia encountered clinically
Low V/Q
Where low V/Q tend to arise from and why
Arises in some alveoli due to local alveolar hypoventilation due to some focal disease
What type of treatment is effective in hypoxaemia due to low V/Q
Small increases in FIO2
What is a shunt
When blood passes from the right to the left side of the heart without encountering ventilated alveoli
Do large shunts respond well to increases in FIO2
No
Give 4 reasons as to why pulmonary hypertension occurs
Pulmonary vasoconstriction
Pulmonary arterioles (muscle hypertrophy and intimal fibrosis)
Loss of capillary bed
Secondary polycythaemia
What is Chronic (hypoxic) Cor Pulmonale
The hypertrophy of the right ventricle that results from disease affecting the function and/or structure of the lung
