Question 13

Draw (include labels and normal values) a normal spirometry trace in a young adult (20% of marks). Describe the changes seen in the spirometry, and the respiratory system overall, in pregnancy at term (80% of marks).

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College Answer

This question was generally handled well. Significant variation exists in normal values 
between textbooks, and examiners took account of this variation. Some candidates failed to 
provide any normal values or gave values not in accord with the traces they provided. Some 
candidates confused spirometry (volume/time) with flow volume loops or even a forced 
expiratory volume trace. These scored no marks. The second part was not well answered by 
some candidates with failure to describe changes - or even contradicting correctly graphed 
changes (for example the reduction in residual volume with pregnancy described as 
increased). Memorising curves needs to be accompanied by understanding. No marks were 
awarded for detailed discussion of the Haldane effect, as this was not asked. Candidates are 
reminded to read and answer the question.