Detailed Description:

Postoperative delirium (POD) and postoperative neurocognitive disorder (PND) increase the length of hospital stay, morbidity and mortality, especially in elderly patients. Although several risk factors were determined and incidence trials were performed on the development of POD and PND, there has not yet been a multicentre, large-participant study in Turkish population. The EJA guideline recommends depth of anaesthesia monitoring, especially in frail patients since intraoperative burst suppression increases the risk of PND. American guideline emphasizes that the effect of processed EEG monitoring on POD cannot be fully demonstrated, but it may reduce PND. Yet, processed EEG monitors, when simplified to an index number, may not accurately reflect the depth of anaesthesia. To detect vulnerable patients, EEG training can be easily implemented. Thus, the incidence of POD and PND may decrease. Additionally, not just EEG monitoring but also regular assessment of patients' stress, anxiety, pain, nausea, vomiting, thirst, and hunger during the pre-and postoperative period and better communication with the patients would reduce the risk of POD. That's why we will use the Safe Brain Initiative (SBI) approach. The SBI approach monitor, detect and help physicians and all perioperative team members to decrease and avoid the adverse side effects of surgery and anaesthesia. In this "before and after" design trial the incidence of POD and PND will be compared before and after education which consists processed EEG and SBI approach. The primary aim of the study is to determine the effect of education which consists processed EEG monitoring and regularly assessment of patient's stress, anxiety, pain, nausea, vomiting, thirst, hunger and better communication at the pre- and postoperative period on the incidence of POD. The secondary aim of the study is to assess the effect of the Safe Brain Initiative approach on patients' thirst feeling, stress-anxiety levels, postoperative pain, postoperative nausea and vomiting, well-being, satisfaction, length of PACU or recovery room stay, length of hospital stay, incidence of PND and in hospital and 3-month mortality. Also, the physicians', nurses' and patients satisfaction will be assessed.}}