Our initial experience of monitoring the autoregulation of cerebral blood flow during cardiopulmonary bypass

Abstract Background: Cerebral blood flow is believed to be relatively constant within an upper and lower blood pressure limit. Different methods are available to monitor cerebral blood flow autoregulation during surgery. This study aims to critically analyze the application of the cerebral oxygenation index (COx), one of the commonly used techniques, using reference to data from a series of clinical registrations. Method: Cerebral blood flow was monitored using near infrared spectroscopy, while cerebral blood pressure was estimated by recordings obtained from either the radial or femoral artery in 10 patients undergoing cardiopulmonary bypass. The association between cerebral blood flow and blood pressure was calculated as a moving continuous correlation coefficient. A Cox index > 0.4 was regarded as a sign of abnormal cerebral autoregulation. Recordings were examined to discuss reliability measures and clinical feasibility of the measurements, followed by interpretation of individual results, identification of possible pitfalls and suggestions of alternative methods. Results and Conclusion: Monitoring of cerebral autoregulation during cardiopulmonary bypass is intriguing and complex. A series of challenges and limitations should be considered before introducing this method into clinical practice.