SERIES: TISSUE REMODELLINGEffects of childhood respiratory diseases on the anatomical and functional development of the respiratory system
Section snippets
INTRODUCTION
The anatomical and functional development of the respiratory system may be affected by insults to the lung that are of an infectious, metabolic/toxic, solely inflammatory, traumatic or genetic nature, and this may commence prenatally. Whether or not structural and functional damage to the lungs and airways occurs depends on factors such as the timing, severity and duration of the insult, the host response, the subsequent repair process and the effects of initial and chronic treatment, if
PHYSIOLOGICAL DEVELOPMENT OF THE RESPIRATORY SYSTEM
The prenatal and postnatal differentiation, development and dimensional growth of the lungs and airways have been the topic of several reviews.2., 3., 4., 5., 6. The human bronchial tree is formed in the first trimester of pregnancy. By the end of gestation, airways are complete in number; structural maturation and dimensional growth occur thereafter. Alveoli begin to appear around the 28th week of gestation and exhibit an enormous increase in number in the first 2 years of age, only to slow
Passive smoking
Of all possible chronic prenatal intoxications, prenatal passive smoking is probably the most prevalent (and preventable) and the most investigated cause of chronic lung disease in childhood and adults. The prenatal growth of lungs and airways is diminished as a result of passive smoking,20., 21., 22., 23. and there is no reason to assume that catch-up growth occurs in later life.24
Recent animal studies indicate that alveolar attachments in the developing lung are reduced by passive smoking,25
CONCLUSIONS
Little appears to be known with certainty with respect to the long-term effects of early insults on the respiratory system, and we are left with much room for speculation and investigation. Prospective studies are required to provide a more adequate evaluation of the effects of disease on the development of the respiratory system but for most disorders, only cross-sectional studies are available, if indeed any reports exist. Another important limitation of most studies is that the reversibility
PRACTICE POINTS
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A significant proportion of adult lung disease can be attributed to insults to the lung during pregnancy and early childhood.
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Published outcome studies describing the net result of disease and treatment on lung function growth in childhood respiratory disease may be outdated due to altered treatment.
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The relationship between remodelling and functional changes in childhood respiratory diseases is largely unknown.
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The hypothesis that early anti-inflammatory treatment in childhood asthma favours
RESEARCH DIRECTIONS
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Improvement or development of convenient tests to evaluate inflammation and function of peripheral airways in young children.
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Prospective reversibility studies of airways obstruction in asthma involving sensitive test for small airway patency.
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International standardised diagnosis, treatment and follow-up of rare respiratory disorders to evaluate effects of treatment on long-term outcome.
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Prospective studies on the effects of aggressive treatment in early childhood respiratory disease on long-term
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