The Effect of Home and Hospital Mask Designs on Respiratory Variables in Healthy Volunteers

The goal of this randomized cross-over study is to investigate whether the design of non-invasive ventilation (NIV) mask impacts respiratory variables in healthy volunteers on NIV therapy. The main questions it aims to answer are:

* To assess if mask design impacts the ventilatory ratio in healthy volunteers. * To assess if mask design impacts transcutaneous CO2, respiratory rate, and tidal volume in healthy volunteers.

Participants will attend five study visits:

* Visit 1. Participants will be fitted to use non-invasive ventilation briefly to acclimatize them to using the therapy. * Visit 2. Participants will receive NIV with one of four masks. They will be asked to breathe through their mouth or through their nose, with a break from NIV in between the two sessions of NIV. * Visits 3-5. Participants will receive NIV with one of the other three masks, repeating Visit 2.