Recruitment and exclusions
The study began in June 2019 and was stopped in March 2020 due to the Covid-19 pandemic. This analysis includes the 86 participants out of the 150 expected enrolments (43 in group N, 43 in group D) from Toulouse (n = 25) and Clermont-Ferrand (n = 25) in France, the University Hospitals Coventry and Warwickshire NHS Trust (n = 16) and Oxford University Hospitals NHS Foundation Trust (n = 20) in the UK.105 participations had been recruited, but nine were excluded because of missing or invalid data and a further nine because of a protocol violation (they had already performed more than 10 fiberoptic intubations). Finally, one participant had been recruited twice: only the first of those attempts was kept for analysis.