Operative and anaesthetic factors influencing on delirium in the intensive care unit: An Analysis of electronic health records

Aims and objectives To analyse the operation, anaesthesia and recovery‐related factors affecting the occurrence of delirium in the intensive care unit. Background The occurrence rate of postoperative delirium is high in surgical patients. Postoperative delirium most frequently occurs usually within 3 days after an operation. Design This study used a secondary data analysis based on a case–control study. Methods This study analysed data extracted from the electronic health records at a university hospital from October 2009–July 2015. One hundred and eighty patients with delirium admitted to the intensive care unit through the recovery room after surgery, and 720 nondelirium controls were included. A total of 17 variables were selected, and hierarchical logistic regression was performed to identify operative and anaesthetic factors influencing on delirium. STROBE statement was applied for reporting this study. Results The operation, anaesthesia and recovery‐related factors increasing the risk of delirium included Class II or higher in the classification system of American Society of Anesthesiologists physical status, continuous remifentanil infusion and lower than seven‐point postanaesthesia recovery score at the time of admission to the recovery room. Conclusion The operative and anaesthetic factors influencing the occurrence of delirium should be assessed when a patient is admitted to the ICU following an operation even if a patient is conscious. Relevance to clinical practice Identifying operative and anaesthetic risk factors for delirium can improve the prevention intervention and the patient outcome in the intensive care unit.