A Call for Real-Time Bispectral Index and Electroencephalogram Monitoring in a Patient Undergoing Aortic Surgery

A 77-year-old woman underwent replacement of the ascending aorta and aortic valve. Before separation from cardiopulmonary bypass, the pump flow was reduced to 0-to-1.1 L/min/m² for four minutes at a tympanic temperature of 34.3°C to perform additional sutureing for aorta-graft anastomosis. Postoperative magnetic resonance imaging revealed watershed cerebral infarction. An offline scalogram of intraoperative electroencephalograms obtained from the bispectral index monitor, which was generated by using continuous wavelet transform with complex Morlet wavelets, readily visualized the process of development of cerebral infarction preceding a significant decrease of regional cerebral oxygen saturation during the low-flow period of cardiopulmonary bypass. The present case demonstrated the possible importance of real-time bispectral index and electroencephalogram monitoring in patients undergoing cardiovascular surgery, especially those undergoing high-risk procedures under hypothermic circulatory arrest.