Fig. 3

Course of respiratory parameters between survivors and non-survivors. a Respiratory rate, b Oxygen saturation, c S/F ratio, d ROX index. Parameters are depicted as Boxplot, p-values: Mann–Whitney U-test for continuous variables and Chi-square test for categorical variables. * represent p-values < 0.05, ** represent p-values < 0.001. T time point, prior prior to HFNO initiation, Q quartile, IQR interquartile range, S/F ratio SpO2/FiO2 ratio, ROX index respiratory oxygenation index (SpO2/FiO2/respiratory rate)