Abstract
High-flow nasal cannula (HFNC) is now a commonly used noninvasive method of providing respiratory support to children and young people. Its rapid spread into varied clinical applications has often left assessment of the evidence of its mechanism of action and clinical benefit lagging behind its uptake. This review will discuss the proposed mechanisms of action of HFNC, review the evidence base for its use, cover its applications in paediatrics and outline its limitations.