The overall objective of this randomized study is to evaluate the efficacy of HVNI, in comparison to NIPPV, to clinically stabilize and provide respiratory therapy to patients who have COPD with moderate-to-severe hypercapnic respiratory distress upon presentation. It is hypothesized that HVNI is comparable to NIPPV in the stabilization and relief of moderate-to-severe hypercapnic respiratory distress upon presentation, by relieving the patient's dyspnea (breathlessness) within 4 hours to a comparable degree to NIPPV.