Aging and the respiratory system.
All the components of the respiratory system are affected by aging, though at different rates: i) the lung elastic recoil decreases; ii) PaO2 decreases and the D(A-a)O2 increases; iii) the chest wall becomes stiffer; iv) the inspiratory muscles loose strength; and v) the respiratory centres are less sensitive. Residual volume, closing volume and function residual capacity increase, whereas vital capacity and FEV1 progressively decrease. The flow volume curve becomes more convex to the volume axis at low lung volume. Whether these changes are due to aging or associated with aging is a matter of debate. However, the aging lung is more fragile in the face of respiratory and systemic diseases than the respiratory system of young adults. Nutrition, smoking habits and sleep-related disorders also affect the respiratory system. Although bronchial asthma may also appear in the elderly, chronic obstructive pulmonary disease is one of the most common respiratory diseases in advanced life and is a major cause of respiratory failure and ICU admission. Age in itself is not a risk factor of respiratory failure, but elderly patients have an increased risk of mortality for both acute respiratory failure (the failing lung), and exacerbated chronic ventilatory failure (the failing pump). Although advanced age can influence the final outcome of elderly patients from the intensive care unit (ICU), admission to the ICU as well as the institution of mechanical ventilation should not be denied on the basis of age alone, since the severity of illness, prior health status and admitting diagnosis have more weight than age in the final outcome.