The study was designed as a single-center, randomized, prospective study and approved by the University Hospital Olomouc and Faculty of Medicine and Dentistry, Palacky University Olomouc ethics committee. It comprised patients over 18 years of age undergoing surgery at the hospital's Department of Surgery I and subsequently placed in an ICU bed. As there were no limitations concerning the type of procedures, these involved a wide range of abdominal and thoracic surgeries; however, all of them were elective procedures. No patients were critically ill, being classified as ASA III or less.