Caption to figures.
Figure 1. CONSORT flow chart. *Unknown congenital immunodeficiency; **prolonged HFNC treatment after PICU admission and enrollment
Figure 2. Intubation rate at each center.
Figure 3. Trend of pH, PaO2/FiO2, PaCO2, heart rate (HR) and respiratory rate (RR) between groups. None of the clinical or respiratory parameters differed significantly between groups; however, they all showed a significant improvement over time (p<0.001 in all cases)