Statistical analysis
H-VAL
EVENTS
The primary outcome is the rate of successful intubations at first attempt as a fraction of dichotomous events. In a first analysis step we test the hypothesis, that neither video assisted laryngoscopy with a Macintosh-shaped blade (M-VAL) nor video assisted laryngoscopy with a hyper-angulated blade (H-VAL) are inferior to conventional direct laryngoscopy (CDL) with regard to the primary outcome. In terms of the statistics, this corresponds to testing the Null hypothesis that at least one of the interventions M-VAL or H-VAL is inferior to CDL. Both Null hypotheses will be tested for separately. The overall type-I error will be set to 5%. Thus, both Null hypotheses will be tested on a local significance level of 0.025 using a one-sided Z-test with unpooled variance. Non-inferiority is defined as described in subsection “sample size”.Only if both Null hypotheses can be rejected will there be a second analysis step where the single interventions M-VAL and H-VAL will be tested pairwise for superiority using a two-sided Z-test with unpooled variance. As we apply the principle of fixed sequence hierarchical testing, this analysis can be performed at a local significance level of 0.05 to meet the family-wise error rate of 0.05.A planned interim analysis will be conducted after 200 randomized interventions. This will first and foremost happen to review feasibility and data quality before expanding to additional study sites. We do not foresee any substantial safety concerns in this trial which would need to be assessed at this stage.