i) | A review of the literature on outcomes of pre-hospital advanced airway management (unpublished), including a recent Cochrane review on the same topic [30]. |
ii) | A recent survey of Norwegian helicopter emergency medical service (HEMS) physicians' own perceptions of the safety and quality of pre-hospital airway management in their system [19]. |
iii) | Audit of data from patients with severe traumatic injury treated by the assessed HEMS systems in the 1994 -- 2005 period (unpublished data, manuscript in preparation). |
iv) | Expert judgement by three of the authors (SS, HML and ARN) as experienced HEMS physicians and one independent HEMS physician from the system assessed. |
v) | The literature cited in this study. |