1. Department of Emergency Medicine, University of Thessaly, School of Medicine, General Hospital of Larisa, Thessaly, Greece;
2. Department of Respiratory Medicine, University of Thessaly, School of Medicine, General Hospital of Larisa, Thessaly, Greece;
3. Department of Biostatistics and Epidemiology, Auckland University of Technology, Auckland, New Zealand;
4. Department of Anesthesiology, University of Thessaly, School of Medicine, General Hospital of Larisa, Thessaly, Greece;
5. First Department of Critical Care Medicine & Pulmonary Services, Medical School, National and Kapodistrian University of Athens, Evangelismos Hospital, Athens, Greece