Permanent damage? Congenital defect?
This summarizes the findings of the longitudinal study on lung growth:
- In the groups of asthma patients and a normal population of adolescents attending a secondary school, comprising an age range 6-19 year, the evidence is that in the great majority of cases growth of lungs and airways is isometric: a child's lung is indeed a minitiature of an adult lung.
- In the population that was studied the isometric growth pattern is not affected by respiratory disorders, but subjects who never experienced respiratory disorders on average generate higher expiratory flows at a specified lung volume than those who did; this seems to indicate that the former group on average have wider airways.
It is not clear how to explain the second finding. Possibly some were born with narrower airways, as a result of which viral and other airway disorders had more pronounced effects and hence generated more symptoms. Conversely, one could argue that in individuals who had recurrent respiratory symptoms during infancy this was symptomatic of a process that inflicted lasting damage to their lungs. In the latter case prevention, notably of viral diseases, would be called for. The fact that cohort effects in lung function have been demonstrated might give credence to the idea of early damage. A cohort effect implies that for example the VC and the FEV1 of someone who is 20 year old now is larger than that of a 20-year old individual 40 years ago.
- Merkus PJFM, van Pelt W, van Houwelingen JC, van Essen-Zandvliet LEM, Duiverman EJ, Kerrebijn KF, Quanjer PH. Inhaled corticosteroids and growth of airway function in asthmatic children. Europ Respir J 2004; 23: 861-868.
- Weiss ST, Tosteson TD, Segal MR,
Tager IB, Redline S, Speizer FE. Effects of asthma on pulmonary
function in children. Am Rev Respir Dis 1992; 145: 58-64.
These authors come to comparable conclusions, although their findings suggest that asthma in girls is associated with a a decreased rate of growth of FEV1.