Dynamic cerebral autoregulation: A marker of post-operative delirium?

OBJECTIVE: We investigated the potential association of cerebral autoregulation (CA) with postoperative delirium (PD), a common complication of cardiac surgery with cardiopulmonary bypass (CPB). METHODS: In patients undergoing coronary artery bypass graft (CABG) surgery with CPB, cerebral blood flow velocity (CBFV) and blood pressure (BP) were continuously recorded during 5-min preoperatively (T1), after 24 h (T2), and 7 days after procedure (T3). Prospective multivariate logistic regression analysis was performed to determine the independent risk factors of PD. Autoregulation index (ARI) was calculated from the CBFV response to a step change in BP derived by transfer function analysis. RESULTS: In 67 patients, mean age 64.3 ± 9.5 years, CA was depressed at T2 as shown by values of ARI (3.9 ± 1.7), compared to T1 (5.6 ± 1.7) and T3 (5.5 ± 1.8) (p < 0.001). Impaired CA was found in 37 (55%) patients at T2 and in 7 patients (20%) at T3. Lower ARI at T1 and T2 were predictors of PD (p = 0.003). CONCLUSION: Dynamic CA was impaired after CABG surgery with CPB and was a significant independent risk factor of PD. SIGNIFICANCE: Assessment of CA before and after surgery could have considerable potential for early identification of patients at risk of PD, thus reducing poor outcomes and length of stay.