^EFFECTS OF AGEING ON RESPIRATORY 

 FUNCTION IN MAN 



D. V. Bates, m.d., m.r.c.p., 

 AND R.V. Christie, m.d., d.Sc, f.r.c.p., 



Dunn Laboratories, St. Bartholomew's Hospital, London. 



I HAVE been asked to discuss the effects of ageing on 

 respiratory function. What I propose to do is to describe 

 briefly some of the tests which are now used to assess res- 

 piratory function and to contrast the performance of young 

 individuals w ith the performance of those who have reached 

 middle age. I also propose to bring the disease emphysema 

 into the picture because as far as respiratory function is 

 concerned emphysema is a gross exaggeration of w hat happens 

 to the lungs with advancing years. 



Fig. 1 shows the age distribution of the various groups 

 investigated. The sole reason for choosing thirty-five years 

 as the dividing line between young and old was that the 

 primary purpose of this investigation was to study the 

 changes which occur in emphysema, a disease which is rarely 

 found before the age of thirty-five. 



The vital capacity is clearly reduced with age, a fact which 

 has been known for at least half a century. In Fig. 2 the 

 "young normals" have a mean vital capacity of 4-8 litres 

 while in the "old normals" the mean is 3-5 litres, a difference 

 which is statistically significant. This change is not due to any 

 decrease in the distensibihty of the lung itself; it is almost 

 certainly due to fixation of the thoracic cage, arising from a 

 variety of anatomical changes such as decreased elasticity 

 and immobility of the costal cartilages. In emphysema the 

 vital capacity is still further reduced. 



The volume of the lung increases with age (Fig. 3). In the 

 younger group this averages 2-9 litres while in the middle- 



♦Presented by Prof. R. V. Christie. 



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