The Factors Causing Treatment Failure in Children Receiving Oxygen Therapy With High-flow Nasal Cannula

The goal of this observational study is to identify the variables that predict treatment failure in order to identify the patients in which HFNC treatment may fail and not delay the transition to advanced respiratory support treatments in these patients. The main questions it aims to answer are: * What factors contribute to the failure of HFNC treatment in these children? * What is the frequency of HFNC treatment failure in children with moderate and severe respiratory distress? Researchers will compare the group whose HFNC treatment was successful with the group whose HFNC treatment failed to identify factors that cause treatment failure.