Asthma, rhinitis, and the unified airway.

Patients with rhinitis and rhinosinusitis are commonly treated in otolaryngologists' offices. Many of these patients have concurrent lower respiratory diseases such as asthma. The simultaneous presence of upper and lower airway diseases occurs frequently, and has resulted in the unified airway model, which describes the close relationships between these inflammatory diseases. Understanding the coexistence of respiratory illnesses has implications for the diagnosis and management of both upper and lower airway conditions. It is important for otolaryngologists and otolaryngology nurses to be aware of these common comorbid processes, and to evaluate for the presence of asthma in all patients with upper airway conditions such as rhinitis and rhinosinusitis. This paper will discuss the epidemiology, pathophysiology, mechanisms, and diagnosis and treatment considerations in patients with unified airway diseases.