Length of stay in the intensive care unit is one of the most important factors affecting health management. There are several factors that influence prolonged ICU stay, and these factors include psychosocial factors and institutional factors. Prolonged stay in the intensive care unit can also have negative consequences. In patients with a prolonged length of stay, defined as 1 week or longer of mechanical ventilation, patient age and length of stay in ICU affect motor and cognitive functional dependence 1 year after discharge from ICU, regardless of diagnosis at admission and severity of illness. Objective of the research: The objectives of the research in this paper are to investigate the age and gender of the respondents who are imprisoned in the OIL, to investigate from which department the respondents are most often employed in the OIL, what was the average number of days in bed. We will also investigate which complications occurred most often in patients, and how much the treatment costs were. Respondents and methods: The research was conducted with a retrospective analysis in the period from 2020 to 2021. The data used in the research were obtained through a retrospective analysis from the hospital information system (IBIS), the Institute for Intensive Care and the Department for Intensive Care of Cardiac Surgery Patients of the Clinic for Anaesthesiology, Intensive Care Medicine and Pain Management of the Rijeka Clinical Hospital Center. 90 respondents participated in the research. Results: Results: The research used data from a total of 90 patients who were in the department of the Department of Intensive Care and the Department of Intensive Care of Cardiac Surgery Patients of the Clinic for Anesthesiology, Intensive Medicine and Pain Management of the Rijeka Clinical Hospital Center. According to gender, the majority of patients were male (75%). The average age of all subjects was 59 ± 19 years. The average number of treatment days for all patients is 22 ±11 days. Most subjects (75%, N=68) were discharged from the ward between the 13th and 21st day of treatment. The largest number of respondents were from the departments of neurosurgery and (13%) pulmonology (31%). For the majority of respondents (73%), the cost of treatment was less than 26,500 euros. Conclusion: According to gender, male respondents prevailed. According to the age structure, the average age of the respondents was over 65 years. The average length of stay at OIL was 21 days. Most of the subjects died during the treatment. The research leads to the conclusion that room for progress is needed in order to recognize complications in time, prevent mortality and reduce the length of stay in the intensive care unit.