Accuracy of VO₂ estimation according to the widely used Krakau formula for the prediction of cardiac output.

"Declarations Conflict of interestT. Reiter, J. Kerzner, G. Fette, S. Frantz, W. Voelker, G. Ertl, W. Bauer, C. Morbach, S. Störk and G. Güder declare that they have no competing interests. All procedures performed in studies involving human participants or on human tissue were in accordance with the ethical standards of the institutional and/or national research committee and with the 1975 Helsinki declaration and its later amendments or comparable ethical standards. Approval of the ethical committee was waived as the Data Ware House runs on standard operating procedures that are controlled and approved by the institution’s data protection officer. Informed consent was waived due to the retrospective nature of the study and anonymous data analysis. Conflict of interest T. Reiter, J. Kerzner, G. Fette, S. Frantz, W. Voelker, G. Ertl, W. Bauer, C. Morbach, S. Störk and G. Güder declare that they have no competing interests."

"Funding The Comprehensive Heart Failure Center supported the work, funded by the German Federal Ministry of Education and Research (Bundesministerium für Bildund und Forschung) with grant number 01EO1504. The publication was supported by the Open Access Publication Fund of the University of Würzburg. Funding Open Access funding enabled and organized by Projekt DEAL."