Characteristics and Risk Factors for Delirium in Critically Ill Cardiac Surgery Patients: An Observational Study

Background/Objectives: Delirium is a frequent and clinically significant complication in cardiac surgery patients and is associated with prolonged mechanical ventilation, longer Intensive Care Unit (ICU) stay, increased mortality, and long-term cognitive impairment. However, evidence regarding perioperative factors associated with delirium occurrence in cardiac surgery ICU patients remains limited. This study aims to investigate clinical factors associated with postoperative delirium in cardiac surgery patients admitted to the ICU. Methods: A single-center, prospective, observational study was conducted in a 14-bed cardiothoracic ICU in central Italy. Consecutively enrolled adult patients undergoing cardiac surgery were assessed for delirium using the Italian-validated Intensive Care Delirium Screening Checklist (ICDSC) every eight hours for five days. Univariate analysis and multivariate logistic regression were performed to identify factors associated with delirium occurrence. Results: A total of 175 patients were included, and delirium occurred in 44.6%. In the univariate analysis, patients with delirium presented significantly longer mechanical ventilation (10.5 vs. 8.0 h; p = 0.04) and higher APACHE II scores (p = 0.01). In the multivariable analysis, lower Glasgow Coma Scale (GCS) scores were independently associated with delirium occurrence (OR = 0.84; 95% CI: 0.71-0.99; p = 0.04). Urgent admission (OR = 2.02; p = 0.06) and mean arterial pressure (OR = 0.97; p = 0.08) did not reach statistical significance in the multivariable model. Conclusions: Delirium is highly prevalent after cardiac surgery. Lower postoperative GCS scores may represent an early marker of postoperative neurological vulnerability associated with delirium occurrence. Further multicenter studies are warranted to improve delirium risk stratification and clarify the mechanisms underlying postoperative cognitive dysfunction.