Enrolled in the study were patients staying at the ICU of the Department of Anesthesiology and Intensive Care Medicine, Faculty of Medicine and Dentistry, Palacky University Olomouc and University Hospital Olomouc, between 1 January 2011 and 31 December 2015. The participants were all patients older than 18 years of age consecutively admitted to the ICU, who met HAP criteria.