Background: Oxygen (O2) is a mainstay of treatment in acute severe asthma but how it is administered varies widely. The objectives were to examine whether a trial comparing humidified O2 to standard O2 in children is feasible, and specifically to obtain data on recruitment, tolerability and outcome measure stability.
Methods: Heated humidified, cold humidified and standard O2 treatments were compared for children (2-16 years) with acute severe asthma in a multi-centre, open, parallel, pilot randomised controlled trial (RCT). Multiple outcomes were assessed.
Results: Of 258 children screened, 66 were randomised (heated humidified O2 n = 25; cold humidified O2 n = 21; standard O2 n = 20). Median (IQR) length of stay (hours) in hospital was 37.9 (29.1), 52 (35.4) and 49.1 (29.7) for standard, heated humidified and cold humidified respectively and time (hours) on O2 was 15.9 (9.4), 13.6 (14.9) and 13.1 (14.9) for the three groups respectively. The mean (standard deviation) time (hours) taken to step down nebulised to inhaled treatment was 5.6 (14.3), 35.1 (28.2) and 32.7 (20.1). Asthma Severity Score decreased in all three groups similarly, although missing data prevented complete analysis. Humidified O2 was least well tolerated with eight participants discontinuing their randomised treatment early. An important barrier to recruitment was research nurse availability.
Conclusion: Although, the results of this pilot study should not be extrapolated beyond the study sample and inferential conclusions should not be drawn from the results, this is the first RCT to compare humidified and standard O2 therapy in acute severe asthmatics of any age. These findings and accompanying screening data show that a large RCT of O2 therapy is feasible. However, challenges associated with randomisation and data collection should be addressed in any future trial design.