Conclusion: The percentage success observed was similar to that published. In this sample, the failure of HFNC was only associated with an initial pCO(2) >= 55 mmHg. On there being no complications reported as regards it use, it is considered safe, although a randomised, controlled, multicentre study is required to compare and contrast these results. (C) 2015 Sociedad Chilena de Pediatria. Published by Elsevier Espana, S.L.U.