Age-related changes in the respiratory system
Age-related physiologic changes contribute to impaired pulmonary function and to the increased prevalence of COPD with age. In general, these changes include a progressive reduction in compliance of the chest wall, reduction in strength of the respiratory muscles, and anatomical changes to the lung parenchyma and peripheral airways.5,6 Changes in thorax shape due to osteoporosis and kyphosis may induce inefficiencies in chest wall mechanics.5,6 The functional consequences of these changes are decreased peak inspiratory and expiratory airflows, vital capacity, and efficiency of gas exchange. Hankinson et al studied the spirometry results of 4,634 lifetime nonsmoking US adults without a diagnosis or symptoms of chronic pulmonary disease and found that both men and women demonstrated a reduction of forced expiratory volume in one second (FEV1) of about 200–300 mL every decade between the ages of 20 and 70 years.7 Based on their regression model of the observations in this cross-sectional study, at age 70 years, FEV1 would be expected to decrease by about 30% and forced vital capacity (FVC) would be expected to decline by about 20% compared with values at age 20 years. Importantly, at age 70 years, the expected FEV1/FVC ratio would be about 74%, a value approaching the 70% criterion used for diagnosing significant obstruction.3 Additionally, the area for gas exchange declines linearly from the third decade of life and is decreased by one third by about age 85 years.5 Loss of elastin leads to increases in residual volume and significant increases in dead space.5 All of these changes contribute to an increased likelihood of COPD in the elderly, and critical to geriatric considerations, these age-related changes may be less amenable to treatment.
Age-related changes in the respiratory system
Age-related physiologic changes contribute to impaired pulmonary function and to the increased prevalence of COPD with age. In general, these changes include a progressive reduction in compliance of the chest wall, reduction in strength of the respiratory muscles, and anatomical changes to the lung parenchyma and peripheral airways.5,6 Changes in thorax shape due to osteoporosis and kyphosis may induce inefficiencies in chest wall mechanics.5,6 The functional consequences of these changes are decreased peak inspiratory and expiratory airflows, vital capacity, and efficiency of gas exchange. Hankinson et al studied the spirometry results of 4,634 lifetime nonsmoking US adults without a diagnosis or symptoms of chronic pulmonary disease and found that both men and women demonstrated a reduction of forced expiratory volume in one second (FEV1) of about 200–300 mL every decade between the ages of 20 and 70 years.7 Based on their regression model of the observations in this cross-sectional study, at age 70 years, FEV1 would be expected to decrease by about 30% and forced vital capacity (FVC) would be expected to decline by about 20% compared with values at age 20 years. Importantly, at age 70 years, the expected FEV1/FVC ratio would be about 74%, a value approaching the 70% criterion used for diagnosing significant obstruction.3 Additionally, the area for gas exchange declines linearly from the third decade of life and is decreased by one third by about age 85 years.5 Loss of elastin leads to increases in residual volume and significant increases in dead space.5 All of these changes contribute to an increased likelihood of COPD in the elderly, and critical to geriatric considerations, these age-related changes may be less amenable to treatment.
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