Noninvasive ventilation (NIV) is a form of ventilation delivered by a mask and is an important mode of treatment in patients with both acute and chronic respiratory (breathing) failure. Humidification is widely accepted as an essential part of the ventilation strategy in patients receiving invasive ventilation (i.e. via a tube inserted into the mouth), but its role during NIV use is not proven. Consequently, there is a variation in practice with regard to humidification during NIV. Humidification is important in maintaining upper and lower airway mucosal function and patients requiring NIV often report symptoms, such as throat dryness, due to a lack of airway humidity. Success of NIV in the acute setting is dependent on many factors including, patient tolerance of NIV during the acute phase. In patients with chronic obstructive airways disease (COPD), poor tolerance results in NIV failure, which necessitates endotracheal intubation or treatment failure. Furthermore, invasive ventilation increases the risk of a hospital acquired pneumonia, which is associated with a worse outcome. In the long term setting of NIV use, again patients frequently report symptoms due to drying of the airways and adherence to NIV can be highly variable. Adherence in these patients is important in improving both quality and length of life. Humidification devices may be technically effective, but clinicians have concerns regarding potential negative effects of these devices. There is a requirement to evaluate the use of humidification in both the acute and long term use of NIV, particular, in terms of patient ventilator interaction, which will impact on comfort and adherence to NIV. This will effect the overall effectiveness of ventilation. The investigators propose a randomised controlled trial to investigate the effects of a humidification system during noninvasive ventilation.

Inclusion Criteria:

• hypercapnic respiratory failure
• age > 18
• requiring non-invasive ventilation

Exclusion Criteria:

• psychiatric illness
• pregnancy