The link between upper and lower respiratory disease.

The upper and lower airways are connected anatomically, physiologically, and immunologically. Epidemiologic studies provide strong evidence of associated dysfunction. Therapeutic modalities with indications for treatment of one portion of the airway are frequently used for the other. These include antihistamines, inhaled or nasal steroids, cromolyns, and most recently leukotriene receptor antagonists. Studies of the upper airway show that upper airway impairment with allergic rhinitis affects the lower airway and that pharmacological treatment of allergic rhinitis can prevent seasonal asthma. Recently, single-agent allergy sensitization has been shown to prevent the development of asthma. Conflicting data exist regarding the affect of sinus surgery on asthma severity. This review is intended to provide an update of our knowledge of the upper and lower airway connection, highlighting articles published within the last year.