Materials and Methods: This observational and interventional study was performed on patients with suspected BD in emergency departments and intensive care units. CO monitoring was performed for at least 6 h, and cerebral tissue oxygen saturation (ScO2) was recorded. Basal ScO2 values (basal ScO2), ScO2 values after 6 h (end ScO2), mean ScO2 values during monitoring (mean ScO2), and minimum (min ScO2) and maximum (max ScO2) ScO2 values observed during monitoring were recorded for all patients. Patients with diagnosis of BD confirmed by the organ transplantation and brain death committee were enrolled as the BD group and other patients as the non-BD group, and cerebral oxygen parameters were compared.