High-flow nasal oxygen therapy was not inferior to BiPAP : the treatment failed in 87 of 414 patients with high-flow nasal oxygen therapy ( 21.0 % ) and 91 of 416 patients with BiPAP ( 21.9 % ) ( absolute difference , 0.9 % ; 95 % CI , -4.9 % to 6.6 % ; P = .003 ) .