The application of high-flow nasal cannula therapy (TAFCN) in children has grown exponentially in recent years, especially in premature infants and young children with bronchiolitis or acute hypoxemic respiratory failure. More and more scientific evidence is now available on the effectiveness of TAFCN and the fact of breathing a hot, humid gas, is a very intereting characteristic of this therapy. A common situation in infants and young children, is to use mild sedation to avoid anxiety and improve the child's collaboration, during the performance of various procedures or imaging techniques. The times of the techniques are shortened and the greater degree of satisfaction of the parents is also important. A practice not regulated but increasingly used in recent years is to use high flow to withstand sedation in these children. The practice of using a low level of sedation in infants with bronchiolitis requiring high flow has also spread, in order to achieve a better adaptation to the technique, by controlling anxiety and agitation during treatment. There are no studies that address this issue, there are not any consensus on the indication of sedation, nor are there clear criteria of how to do sedation or how to apply high flow. Reality tells us that it is a habitual practice. Studies that delimit the role that sedation plays in children who are going to be subjected to TAFCN are necessary.