Swallowing problems increase the risk for aspiration pneumonia. Other age- and COPD-related issues also contribute to an increased risk.
Weakened immune system
Breathing in a small amount of saliva or food from the mouth is normal. In a healthy, younger person, a strong cough and a hardy immune system ensure that any bacteria that enter the lungs from food or saliva are removed or destroyed before they can start an infection.
People with COPD do have strong coughs, but as their immune system weakens with age, it becomes less able to fight off infection. To make matters worse, people with COPD often do not eat a well-balanced diet, contributing to a poorly functioning immune system as well.
Excessive oral bacteria
Everyone has bacteria in their mouth, but elderly people tend to have more, because of a higher likelihood of dental plaque and a dry mouth. The presence of a feeding tube also can increase oral bacteria, and an endotracheal tube raises the likelihood of aspiration of these bacteria.
Blunted response to inhaled irritants
As humans age, our response to inhaled irritants deteriorates. For example, when people of different ages were asked to inhale an irritant, such as citric acid, older people needed to inhale a greater amount than their younger counterparts before the defense mechanisma coughwas elicited.
This suggests that as we age, when agents are accidentally inhaled down the trachea, the defense mechanism is blunted and we may not cough out things that are aspirated. If the material aspirated has bacteria in it, it may cause aspiration pneumonia.