Author Contributions: Dr Olasveengen had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Thowsen, Steen, Wik.
Acquisition of data: Olasveengen, Thowsen, Wik.
Analysis and interpretation of data: Olasveengen, Sunde, Brunborg, Steen.
Drafting of the manuscript: Olasveengen, Sunde, Steen.
Critical revision of the manuscript for important intellectual content: Brunborg, Thowsen, Wik.
Statistical analysis: Olasveengen, Brunborg.
Obtained funding: Steen.
Administrative, technical, or material support: Thowsen, Wik.
Study supervision: Sunde, Brunborg, Steen, Wik.
Financial Disclosures: Dr Olasveengen reported receiving speakers' fees from Medtronic (Oslo, Norway) and research support from Laerdal Medical Corporation (Stavanger, Norway). Dr Steen reported being a member of the board of directors for Laerdal Medical and the Norwegian Air Ambulance. Dr Wik reported being on a medical advisory board for Physio-Control, consulting for Laerdal, Zoll, and Jolife, and being a principle investigator for a multicenter mechanical chest compression device study sponsored by Zoll. Dr Sunde, Ms Brunborg, and Mr Thowsen did not report any financial disclosures.
Funding/Support: The study was supported by grants from the Eastern Norway Regional Health Authority, Oslo University Hospital, Norwegian Air Ambulance Foundation, Laerdal Foundation for Acute Medicine, and the Anders Jahres Fund.
Role of the Sponsors: The funding organizations had no involvement with the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript
Additional Contributions: Martin Samdal assisted in data collection as required research exposure as a medical student at the University of Oslo and did not receive any financial compensation for his work. Andres Neset is enrolled in a combined MD/PhD program at the University of Oslo and assisted with data analysis and did not receive any financial compensation for his work. Morten Pytte, MD, PhD, provided useful feedback in preparing the manuscript and did not receive any financial compensation for his work. Knut Arvid Kirkebøen, MD (University of Oslo), provided useful feedback in preparing the manuscript and did not receive any financial compensation for his work. Norman Paradis, MD (vice president and chief medical officer at Zoll Circulation), provided useful feedback and advice in preparing the manuscript and did not receive any financial compensation for his work. We thank all of the physicians and paramedics working in the Oslo emergency medical service system.