1 Faculty of Medicine, University of Belgrade, and Department of Anesthesiology and Intensive Care, CHC "Dr. Dragisa Misović - Dedinje", Belgrade, Serbia.
2 Faculty of Medicine, University of Belgrade, and Department of Anesthesiology and Intensive Care, University Clinical Center of Serbia, Belgrade, Serbia.
3 Faculty of Medicine, University of Belgrade, and Institute of Medical Statistics and Informatics, Belgrade, Serbia.