Combined airways: impact of upper airway on lower airway

Purpose of review This article reviews recent literature on the important relationship between the nose, paranasal sinuses and lungs. Recent advances in the understanding of the pathophysiological mechanisms underlying the association between upper and lower airways are discussed. Recent findings Epidemiological, clinical, and immunopathological data demonstrate an important link between upper and lower airways beyond the well recognized association of allergic rhinitis and asthma. Other upper airway diseases including occupational rhinitis, chronic rhinosinusitis, nasal polyposis with or without aspirin sensitivity, and obstructive sleep apnea have all been linked to asthma and/or asthma severity, as well as other lower airway diseases. Although the underlying mechanisms to explain these associations are unclear, recent work suggests the presence of systemic inflammation triggered by both the adaptive and innate immune system as a major driving force in combined airway diseases. Summary Epidemiological data, clinical observations, and immunopathological studies demonstrate an important link between upper and lower airways. An understanding of how the upper airway impacts on lower airway disease has important diagnostic, therapeutic and prognostic implications.