Age-related changes in the respiratory system

Abstract

This article summarises the main structural and physiological changes which take place in the lung from young adulthood to senescence. An understanding of these changes helps the clinician to correctly interpret some results of radiology and pulmonary function frequently seen in clinical practice. An appreciation of the altered physiology and the consequent reduction in pulmonary reserve should alert the physician to the need for a more critical evaluation of the various respiratory parameters measured during illness in an older patient. Rhythmic breathing occurs virtually continuously over a lifetime and the alveolar gas-exchanging surface is brought into contact with more than 270 million litres of air, which may contain harmful particulate matter and noxious gas elements. Thus to separate changes in the respiratory system caused by ageing itself from those caused by environmental or work-related factors is extremely difficult and sometimes impossible. Chronic obstructive pulmonary disease (COPD) is possibly the most important disease entity related to age and environment. Epidemiological studies show that the prevalence of COPD is increasing. In the 1990’s prognostic models of COPD were developed. These have shown that age, ventilatory function, gender and smoking were the major determinants for the development of COPD. Other important factors were outdoor air pollution and occupation.