Complex Assessment of the Incidence and Risk Factors of Delirium in a Large Cohort of Cardiac Surgery Patients: A Single-Center 6-Year Experience

Abstract

Background. Previous reports provided inconsistent data on the occurrence of postoperative delirium and emphasized its considerable impact on outcome. This study sought to evaluate the incidence and predictors of delirium, together with its relation to cerebral ischemia in a large cohort of cardiac surgery patients in a tertiary high-volume center. Methods and Results. Consecutive patients (n = 8792) were prospectively enrolled from 2003 to 2008. Exclusion criteria were history of psychiatric disorders, use of psychoactive drugs, alcohol abuse, and data incompleteness. Finally, 5781 patients were analyzed in terms of 100 perioperative patient-specific and treatment variables. The incidence of postoperative delirium (DSM IV criteria) was 4.1% and it coexisted with cerebral ischemia in 1.1% of patients. In bivariate analysis, 49 variables were significantly linked to postoperative delirium. Multivariate analysis confirmed that delirium was independently associated with postoperative stroke (logistic odds ratio (logOR) = 2.862, P = 0.004), any blood transfusions (logOR = 4.178, P < 0.0001), age > 65 years (logOR = 2.417, P = 0.002), carotid artery stenosis (logOR = 2.15, P = 0.01), urgent/emergent surgery (logOR = 1.982, P = 0.02), fasting glucose level, intraoperative oxygen partial pressure fluctuations, and hematocrit. Area under ROC curve for the model was 0.8933. Conclusions. Early identification of nonpsychiatric perioperative determinants of delirium facilitates its diagnosis and might help develop preventive strategies to improve long-term outcome after cardiac surgery procedures.

The Effect of Treatment of Anemia with Blood Transfusion on Delirium: A Systematic Review

“…All studies included surgery patients, 12 studies noncardiac surgery, 10,24-26,32,33,37,38,40-43 10 cardiac surgery, [27][28][29][30][31][34][35][36]39,44 and one study both non-cardiac surgery (69%) and medical patients (31%) with severe anemia. 23 In the studies that looked at transfusion as risk factor, transfusion strategy was well described by Beliaev 23 and Vochteloo.…”

“…Delirium incidence ranged from 3% to 48%. Delirium was assessed by the Confusion Assessment Method in nine studies, 10,24,25,[31][32][33]36,37,40 the DSM criteria for delirium in five studies, 26,27,29,30,35 one study used both methods, 41 seven studies used no validated method, 28,34,38,39,[42][43][44] and one study did not mention which method was used.…”

Postoperative Delirium: A Review of Risk Factors and Tools of Prediction

“…Demographic variables associated with delirium after cardiac surgery include older age and male gender. Many different types of medical comorbidities have been associated with delirium including history of stroke, diabetes mellitus, atrial fibrillation, hypertension, renal dysfunction, anemia, gastritis, hypoalbuminemia, and heart failure [13][14][15][16][17][18][19]. In addition, vascular risk factors have been associated with the development of POD following cardiac surgery, including atherosclerosis [20], peripheral artery disease, cerebrovascular disease [21], carotid artery stenosis, and smoking [22].…”

“…Additionally, the risk of POD increases with increasing urgency [14,15] and complexity of the cardiac operation [13]. For example, valve replacement procedures seem to be higher risk than coronary artery bypass grafting (CABG) [27,55,56].…”

“…Other intraoperative variables reported to increase the risk of POD include lower intraoperative body temperature [57], lower mean perfusion pressures during cardiopulmonary bypass [58], and the use of retrograde rather than antegrade arterial perfusion [59]. High variations of intraoperative oxygen partial pressures, high fluctuations of hematocrit levels, and blood product transfusion are associated with the development of POD [14]. In addition to transfusion [13,60], hemofiltration [15] and increased volume load during cardiac surgery have also been reported to increase the risk for POD [17].…”