Statistical analysis
The primary outcome of this study was the reintubation rate. We assumed the reintubation rates of the HFNC and NIPPV groups to be 50% and 10%, respectively. A sample size of 20 for each group was required to achieve an alpha level of 5% (two tailed) and power of 80%. Sample size calculation was conducted using G*Power, version 3.1.9.4 (University of Kiel, Kiel, Germany). The clinical characteristics and outcomes of the patients in the NIPPV and HFNC groups were compared using Fisher’s exact test (for categorical variables) or an independent-samples 