NIV covers a wide range of therapies, starting from CPAP (for sleep apnea at home) to high levels of ventilatory support in the Intensive Care Unit.
Successful NIV is predicted by improved patient comfort, because the work of breathing is reduced. It is well known that humidification is having a positive effect to patient comfort, therefore NIV tolerance. Severe discomfort related to mouth dryness has been reported.
The cooling of airway mucosa results in heat and moisture loss and drying, which increases airway resistance, resulting in increased work of breathing.