Anesthesiology & resuscitation. Perioperative risk factors for delirium development after elective cardiovascular surgery

Aim. This study was conducted to determine the incidence of delirium after cardiac surgery and its effect on the length of the patient's stay in the ICU and to identify the perioperative risk factors. Methods. This research was a retrospective assessment of 1941 medical records and the course of the perioperative period in patients subjected to elective cardiac surgery. Results. Delirium developed in 193 cases (9.94%); whereas, hyperactive, hypoactive and mixed delirium was observed in 13%, 43% and 44% of the patients, respectively. Most often (26% of the cases), delirium occurred after complex combined surgeries. Independent risk factors for the development of delirium were older age (OR 1.041, 95% CI [1.002-1.081], p = 0.038), EuroSCORE II score (OR 1.286, 95% CI [1.093-1.731], p = 0.025), acute kidney injury (OR 1.306, 95% CI [1.107-1.942], p = 0.0018) and renal replacement therapy (OR 1.399 95% CI [1.361-2.792], p = 0.001). Cardiopulmonary bypass duration and time of clamping of the aorta, postoperative serum creatinine level, need for blood transfusions and duration of mechanical ventilation and duration of ICU stay were identified as predictors and were also significantly higher in the delirium group. Delirium was closely associated with critical illness polyneuropathy (OR 9.201, 95% CI [2.13-38.826], p < 0.001) and neurogenic dysphagia (OR 7.48, 95% CI [1.12-56.07], p = 0.022). Conclusion. The key factors for delirium development in the postoperative period include advanced age, high EuroSCORE II scale and acute kidney injury requiring continuous renal replacement therapy. Delirium significantly increases the duration of mechanical ventilation and the duration of ICU stay.