Postoperative delirium in patients after cardiac surgery: incidence, risk factors and outcomes

Authors:  Judita ANDREJAITIENE, Edmundas SIRVINSKAS, Dominykas DVYLYS,
Gabriele LEGOTAITE, Indre SIMELIUNAITE, Zilvinas VENCLOVAS

Summary: Objective. Postoperative delirium (PD) after cardiac surgery is a serious complication and commonly occurs in critically ill patients admitted in the intensive care unit (ICU). This study sought to assess the incidence and risk factors of postoperative delirium after cardiac surgery. Methods. Data obtained from 323 patients after elective cardiac surgery on cardiopulmonary bypass (CPB) were prospectively analyzed. Delirium was diagnosed postoperatively by the attending physician according to the criteria of the Intensive Care Delirium Screening Checklist (ICDSC), Richmond Agitation-Sedation Scale (RASS), Confusion Assessment Method for the Intensive Care Unit (CAM-ICU) and Nursing Delirium Screening Scale (NU-DESC). Results. The incidence of PD was 28%. Average age of delirious patients was significantly higher than non-delirious patients 69.83±10.01 years vs. 65.83±10.61 years, p=0.003. A past history of stroke was significantly more frequent 17.1% vs 6.7%, p=0.006 and intraoperative use of sodium thiopental was lower 220.49±151.66 mg vs. 266.59±179.18 mg, p=0.008 in delirious patients than non-delirious patients. PD was associated with longer ICU stay 5.8±2.89 vs. 3.86±1.91 days, p<0.001, and with longer stay in the hospital after transfer from ICU 14.51±11.67 vs. 11.10±9.07 days, p=0.016. In multivariate regression analysis independent predictors for PD were age >70 years (OR 2.01, 95%CI 1.17-3.45, p=0.003), previous strokes (OR 2.54, 95%CI 1.1-5.86, p=0.029), length of stay in the hospital before surgery > 6 days (OR 1.85, 95%CI 1.07-3.2, p<0,001), dose of intra-operative sodium thiopental of < 140mg (OR 2.49, 95%CI 1.33-4.65, p=0.009) and re-intubation (OR13.17; 95%CI 1.46-119.09, p=0.022). Conclusions. Our data suggests that PD is a common complication after elective cardiac surgery and is associated with longer hospital and ICU stay following cardiac surgery. Older age, previous strokes, longer pre-operative hospital stay, dose of intra-operative sodium thiopental of < 140mg and re-intubation were associated with increased PD risk. Certain identified risk factors for PD, such as intraoperative thiopental dose and pre-operative hospital stay can be potentially modified in order to reduce PD risk.

Keywords: delirium, postoperative delirium, post-cardiotomy delirium, post-cardiac surgery delirium, cardiac surgery.

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