Inability to enrole subjucts.

The purpose of this study is to determine the feasibility, safety and efficacy of a unidirectional breathing mask (breathe in through the nose and out through the mouth or breathe in through the mouth and out through the nose) in COPD patients with breathing difficulties requiring noninvasive positive pressure ventilation (NPPV).

Inclusion Criteria:

1. Acute hypercapnic respiratory failure as a result of an acute exacerbation of COPD defined as PaCO2 > 50 mmHg, with or without hypoxia, and a respiratory rate of greater than 25/min with the use of accessory muscles of respiration or abdominal paradox;
2. Requiring NPPV as assessed by the managing care team.

Exclusion Criteria:

1. Patients with facial deformity, heavy beard or moustache which prevents a good seal between the mask and the face;
2. Patients who have claustrophobia and cannot wear the mask;
3. Patients who are hemodynamically unstable;
4. Patients who are disoriented and unable to cooperate with the study procedure;
5. DNI or DNR status or patients in whom intubation is contraindicated;
6. Patients who are currently intubated;
7. Patients who recently (< 6months) had an MI or stroke;
8. Pregnant woman; There will be no exclusion based on gender, race or ethnicity.