1. Leskovac General Hospital, Department of Anesthesiology and Reanimatology, Leskovac, Serbia
2. University of Niš, Faculty of Medicine, Clinical Center of Niš, Anesthesiology Clinic, Niš, Serbia
3. University of Priština, Kosovska Mitrovica, Faculty of Medicine, Department of Anesthesiology and Reanimatology, Priština-Gračanica Clinical Hospital Center, Gračanica, Serbia
4. University of Niš, Faculty of Medicine, Clinical Center of Niš, Anesthesiology Clinic, Niš, Serbia, PhD student