The upper and lower airways: the epidemiological and pathophysiological connection

The upper and lower airways do not exist as anatomically and functionally distinct areas. There are important relationships between both the nose and the paranasal sinuses and asthma. Both allergic rhinitis and rhinosinusitis may impact bronchial asthma. The patient with rhinitis should be observed carefully for the development of asthma, and those with asthma should be considered to have either rhinitis or rhinosinusitis.