Aging of the respiratory system: Impact on pulmonary function tests and adaptation to exertion

Life expectancy has risen sharply during the past century and is expected to continue to rise in virtually all populations throughout the world. In the United States population, life expectancy has risen from 47 years in 1900 to 77 in 2001 (74.4 for the male and 79.8 for the female population) [1]. The proportion of the population over 65 years of age currently is more than 15% in most developed countries and is expected to reach 20% by the year 2020. Healthy life expectancy, at the age of 60, is at present 15.3 years for the male population and 17.9 years for the female population [2]. These demographic changes have a major impact on health care, financially and clinically. Awareness of the basic changes in respiratory physiology associated with aging and their clinical implication is important for clinicians. Indeed, age-associated alterations of the respiratory system tend to diminish subjects' reserve in cases of common clinical diseases, such as lower respiratory tract infection or heart failure [3,4]. This review explores age-related physiologic changes in the respiratory system and their consequences in respiratory mechanics, gas exchange, and respiratory adaptation to exertion.