[Usefulness of electroencephalogram and transcranial Doppler sonography for brain function monitoring during...

It is well known that neurologic complications greatly affect the postoperative mortality of patients with aortic arch aneurysm. Selective cerebral perfusion (SCP) has been reported to be useful in maintaining cerebral circulation during aortic arch surgery. However, there has been no appropriate method to evaluate brain function during SCP. The purpose of this study was to introduce two new devices, the Lifescan electroencephalogram (EEG) monitor (Neurometrics) and the TC2-64 (EME) transcranial Doppler sonography (TCD), both used for monitoring brain function during SCP in patients undergoing aortic arch surgery. The Lifescan performs aperiodic analysis, and maps each waveform in relation to its frequency, amplitude, and time of occurrence rather than averaging a large number of waveforms over a given period. The Lifescan shows 80% of the whole amplitude of each wave as the activity edge (AE). The flow velocity of the middle cerebral artery was measured by TCD during SCP. With a decrease in body temperature, the EEG and AE gradually showed a trend toward a slower wave and lower amplitude. When circulatory arrest occurred prior to SCP, EEG and AE rapidly showed burst suppression, which was restored after the introduction of SCP. TCD could measure the flow velocity of the left middle cerebral artery even during cardiopulmonary bypass. The flow velocity disappeared during circulatory arrest and was restored after the induction of SCP. It is concluded that the adoption of EEG and TCD is useful in determining the intraoperative cerebral function during SCP.