We often divide the airway into 2 distinct parts:

• The upper airway (nose, throat, sinuses, epiglottis, larynx, trachea)
• The lower airway (bronchi (airpipes), alveoli (lung tissue) and pleura (lining of the lung))

However, research has taught us that we need to rethink the airway as one unit from top to bottom, the concept of the “united airway.”

There is so much evidence that the upper and lower airways are a continuum of the same “organ:”

• First of all, under the microscope the lining of the nose and lung look very similar, with lots of ciliated cells (lined with little beating hairs) and plenty of mucus glands under the basement membrane.
• Secondly, the nose and chest have similar functions:
  • Both act as a transport system moving air in and out of the lungs
  • Both provide defence against inhaled foreign substances, and in fact work together as a team:
    • Most tiny particles are filtered out by the nose
    • Some irritants and gases are dissolved into the nasal secretions
    • Smaller inhaled particles that reach the lower airway are trapped and cleared by the little hairs (cilia) on the lining.
• Thirdly, nasal and chest diseases often go hand-in-hand:
  • 19–38% of patients with allergic rhinitis (AR) have concomitant asthma
  • 30–80% of asthmatics have allergic rhinitis
  • Changes in the chest lining can even occur in patients with allergic rhinitis in the absence of asthma symptoms!
• Lastly, many treatments help both the nose and chest at the same time, generally targeting the airway lining (for example montelukast, immunotherapy, allergy injections such as anti-IgE).

Because nose and chest are part of one system, poor control of nasal symptoms can lead to poor control of asthma! We need to remember to treat nasal allergies early and effectively in order to control asthma symptoms as well as possible.

Think: “The chest starts in the nose”- think UNITED AIRWAY. WE BREATHE BETTER AS ONE WELL-CONTROLLED UNITED AIRWAY!

References:

• Licari A, Castagnoli R, Denicolò CF et al. The Nose and the Lung: United Airway Disease? Front. Pediatr.2017; 5:44.
• Giavina-Bianchi P. United airway disease: current perspectives.
• J Asthma and Allergy 2016; 9: 93–100