Effect of aging on respiratory system physiology and immunology

Abstract

With the looming expansion of the elderly population of the US, a thorough understanding of “normal” aging-related changes on the respiratory system is paramount. The respiratory system undergoes various anatomical, physiological and immunological changes with age. The structural changes include chest wall and thoracic spine deformities which impairs the total respiratory system compliance leading to increase work of breathing. The lung parenchyma loses its supporting structure causing dilation of air spaces: “senile emphysema”. Respiratory muscle strength decreases with age and can impair effective cough, which is important for airway clearance. The lung matures by age 20–25 years, and thereafter aging is associated with progressive decline in lung function. The alveolar dead space increases with age, affecting arterial oxygen without impairing the carbon dioxide elimination. The airways receptors undergo functional changes with age and are less likely to respond to drugs used in younger counterparts to treat the same disorders. Older adults have decreased sensation of dyspnea and diminished ventilatory response to hypoxia and hypercapnia, making them more vulnerable to ventilatory failure during high demand states (ie, heart failure, pneumonia, etc) and possible poor outcomes.

Ponto ótimo cardiorrespiratório: uma variável submáxima do teste cardiopulmonar de exercício

“…More specifically, in our study we observed that with increasing age, there is an increase in the COP value, a fact that can probably be explained by changes that occur in the respiratory system 28,30 . Evidence has shown a reduction in alveolar surface, increase in the alveolar dead space, conditions that are associated with pulmonary hyperinflation and a reduction in the alveolar-capillary diffusion capacity 30,31 , in addition to a lower VE 29 , which, together with the stiffening of blood vessels 32 contributes to a worst ratio or increase in the V/Q 28,[30][31][32] .…”

“…Regarding the ventilatory variables, it is known that, over the years, there is also a reduction in respiratory muscle strength 26 and some ventilatory indicators, such as forced expiratory volume in one second (FEV1) 27 and forced vital capacity (FVC ) 28 , as well as a less effective response to the increase in PaCO2 at rest 29 .…”

Características clínicas e evolução de pacientes imunocomprometidos não HIV com diagnóstico intra-hospitalar de tuberculose

“…(12) In our study, we found a higher prevalence of dyspnea in patients over 60 years of age, a finding that has been reported in another study (13) and might be due to age-related changes in pulmonary function. (14) Fibrotic/atelectatic changes on chest X-rays were also more common among the patients over 60 years of age, which suggests that many of them had a history of TB. However, we do not have consistent data regarding the history of TB in these cases.…”

Age Effects on Blood Gas, Spirometry, Airway Reactivity, and Bronchoalveolar Lavage Fluid Cytology in Clinically Healthy Horses

“…Aging of the lungs is associated with decreased pulmonary elastic recoil, chest wall compliance, and respiratory muscle strength, as well as an increase in alveolar dead space 3, 4. The basis for these functional changes includes loss of elastin content and resultant increase airspace dimensions.…”

“…Functional consequences of the morphologic alterations in the lungs of older people include increased residual volume and functional residual capacity, decreased maximal expiratory flow rate and forced vital capacity, lower diffusion capacity, and higher ventilation/perfusion mismatch 5. Although no clinical signs are seen in healthy subjects as a result of these functional changes, there is a decrease in the reserve capacity of the lung in the presence of disease and these changes may impact exercise capacity 3. In conjunction with this decline in lung function, over 45% of elderly humans demonstrate an increase in airway responsiveness to nonspecific agonists such as histamine 6.…”