Transcranial doppler assessment of preoperative cerebral blood flow velocity in cardiac surgery patients

Postoperative delirium (POD) is a common and multifactorial complication following cardiac surgery, with cardiopulmonary bypass (CPB) playing a significant contributory role. Impaired cerebral autoregulation (CA) during CPB, particularly in older patients, may lead to cerebral hypo- or hyperperfusion. While several methods exist to assess CA and cerebral blood flow, many require specialized equipment not widely available. This prospective observational study aimed to investigate whether altered cerebral artery flow velocity, measured preoperatively by transcranial Doppler (TCD), is associated with the development of POD. We enrolled 41 patients undergoing elective cardiac surgery with CPB. Bilateral peak flow velocities of the middle cerebral arteries were measured preoperatively using TCD. The mean middle cerebral artery velocity (mMCAv mean ) was calculated for each patient. POD occurred in 21 patients (51%). A lower mMCAv mean was significantly associated with an increased risk of POD. Specifically, each 1 cm/s decrease in mMCAv mean increased the likelihood of POD by 9.2% (odds ratio 0.908; 95% confidence interval: 0.840–0.981; p = 0.015). Reduced cerebral blood flow velocity during CPB, as measured by TCD, is associated with a higher risk of POD. These findings highlight the potential utility of intraoperative TCD monitoring for early identification of at-risk patients and support further research into TCD-guided preventive strategies in cardiac surgery.