Preventive strategies for aspiration pneumonia in elderly disabled persons

Pneumonia is the fourth leading cause of death despite the availability of potent new antimicrobials in Japan. Aspiration of oropharyngeal bacterial pathogens to the lower respiratory tract is one of the most important risk factors for pneumonia. Impairments in swallowing and cough reflexes among disabled older persons, e.g., related to cerebrovascular disease, increase the risk of pneumonia. Thus, strategies to reduce the volumes and pathogenicity of aspirated material should be pursued. Since both swallowing and cough reflexes are mediated by endogenous substance P contained in the vagal and glossopharyngeal nerves, pharmacologic therapy using angiotensin-converting enzyme inhibitors, which decrease substance P catabolism, can improve both reflexes and result in the lowering of the risk of pneumonia. Similarly, since the production of substance P is regulated by dopaminergic neurons in the cerebral basal ganglia, treatment with dopamine analogs or potentiating drugs such as amantadine can reduce the incidence of pneumonia. Furthermore, since mortality from infections correlates with cutaneous anergy, interventions that reverse these age-associated changes in the immune system are also effective. The main theme of this review is to discuss how pneumonia develops in disabled older people and to suggest preventive strategies that may reduce the incidence of pneumonia among these subjects.