Respiratory Changes in Pregnancy

Question 1

What are the changes to the thoracic cage during pregnancy?

Answer 1

Diaphragm displaced upwards

Increased thoracic diameter

Question 2

What are the changes to the upper respiratory tract mucosa in pregnancy?

Answer 2

Increased phagocytic activity

Increased mucopolysaccharide content

Question 3

What is the change in oxygen demand in pregnancy?

Answer 3

20% increased oxygen demand

Therefore pO2 increased and PCO2 decreases

Question 4

What is the change to arterial pH in pregnancy?

Answer 4

Mild respiratory alkalosis due to decreased PCO2

Leads to increased bicarb excretion by the kidneys

Question 5

What is the change to minute ventilation in pregnancy?

Answer 5

Increased by 40%
This is due to an increase in tidal volume by 40%
There is no change to respiratory rate during pregnancy

Question 6

What is the change to residual volume during pregnancy?

Answer 6

Decreased residual volume due to diaphragm displacement