Ref (type)	Population	Outcome, Interventions	Results and statistical analysis	Effect size	Favours
Change in croup score
RCT	15 children (6 months–4 years) evaluated in an emergency department with croup, modified Westley Croup Score (see table 1 ) about 1–5, possible range 0–16 In review	Mean change from baseline in modified Westley Croup Score 20 minutes –2.25 with heliox –1.42 with oxygen 30% alone	P = 0.32 RCT was too small to detect a clinically important difference		Not significant