Preoperative transcranial Doppler and cerebral oximetry as predictors of delirium following valvular heart surgery: a case-control study

Delirium is a frequent and serious complication after cardiac surgery with cerebral hypoperfusion as one from the key pathophysiological mechanisms. Middle cerebral artery (MCA) mean blood flow velocity (MFV) measured by transcranial Doppler has been used as a marker of cerebral perfusion, and cerebral oximetry (rSO(2)) value as a marker of its adequacy. This prospective observational trial examined the predictive value of MCA MFV and rSO(2), measured immediately before induction of anesthesia, for delirium after valvular heart surgery in elderly patients. In 113 patients, delirium was evaluated for 7 days postoperatively, using the confusion assessment method for the intensive care unit. The primary endpoint was the occurrence of postoperative delirium. Overall, 16 patients (14%) exhibited delirium. MCA MVF values could not predict the development of delirium. Preoperative statin use, geriatric depression scale score, and low preoperative rSO(2)(< 60%) showed association with delirium occurrence in univariable analysis. After multivariable analysis, only the low preoperative rSO(2)(< 60%) (OR 6.748, 95% CI 1.647-27.652,P = 0.008) remained as an independent predictor of delirium. Preoperative MCA MFV was not significantly associated with delirium after valvular heart surgery in elderly patients, while a low baseline rSO(2)value was associated with a sevenfold increased risk of delirium.