de Boisblanc 2000.

Methods	Design: Prospective, randomized
Participants	Randomized: 50 Eligible: 250 Completed: 47 Majors exclusions: non‐availability of one of the investigators or significant co‐morbid condition
Interventions	Setting: Emergency Department Interventions: a nebulization of bronchodilators (albuterol and ipratropium bromide) using either 80% helium and 20% oxygen or compressed room air as the driving gas.
Outcomes	Outcome: pulmonary function (FEV1, FVC, FEF25‐75) as % of predicted
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment?	Low risk	Third party randomisation