Patients were randomly assigned to receive high-flow nasal oxygen therapy delivered continuously through a nasal cannula ( flow , @ L/min ; fraction of inspired oxygen -LSB- FiO@ -RSB- , @ % ) ( n = @ ) or BiPAP delivered with a full-face mask for at least @ hours per day ( pressure support level , @ cm H@O ; positive end-expiratory pressure , @ cm H@O ; FiO@ , @ % ) ( n = @ ) .