Medical gases, a bypassed airway and higher gas flows can have significant adverse effects.
If the mucosa is exposed to low humidity for a long period of time, irreversible cell damage will occur. The lungs may already be compromised by pre-existing mucociliary dysfunction (e.g. due to age, smoking, chronic obstructive pulmonary disease (COPD), etc). To avoid further complications, provision of physiological levels of humidity becomes even more important for patients with these conditions.
Humidification allows the airway to maintain a natural balance of heat and moisture - optimizing gas exchange, lung defense and patient comfort.