How aging affects the structure and function of the respiratory system.

Age-associated changes in the lung resemble emphysema. Progressive loss of the aging lung's static recoil forces produces airway closure at lung volumes in the tidal volume range,which leads to decreased arterial Po2. Under conditions that decrease oxygen content of arterial blood, the increase in both ventilation and cardiac output is smaller in elderly persons than in younger subjects. Therefore, less oxygen may be delivered to the tissues. Muscular strength of the respiratory apparatus consistently declines and the chest wall stiffens with advancing age. Thus, the elderly have weaker muscles to act on a chest wall that becomes progressively harder to move. Both maximal inspiratory and expiratory pressures are significantly decreased. Loss of the functional reserve of the respiratory system with age increases the risk of respiratory failure and leaves elderly subjects with decreased compensatory mechanisms for dealing with even moderate stress. The physician must be aware of these problems and provide early and vigorous respiratory care for elderly patients.