[Effect of high-flow nasal cannula oxygen on patients with chronic obstructive pulmonary disease and mild hypercapnia: a retrospective cohort study based on the Medical Information Mart for Intensive Care-IV database].

HFNC can be used in COPD patients with mild hypercapnia, but it cannot replace NIV. The accuracy of ROX index at 4 hours after HFNC treatment in predicting intubation in COPD patients with mild hypercapnia is poor.