Estimation of the propagation direction and spectral properties of the EEG signals registered during sevoflurane anaesthesia using Directed Transfer Function method

Department of Neurology and Epileptology CMKP, Czerniakowska 231 st., 00-416 Warszawa, Polande-mail: eolejarczyk@ibib.waw.plThe aim of this study was to estimate spectral properties and propagation of the EEG signalsregistered during sevoflurane anaesthesia between individual EEG recording channels. Theintensities of activity flows were calculated for delta, theta, alpha and beta waves using the DirectedTransfer Function integration procedure. It was found that delta waves played the dominant role inthe EEG signal propagation during anesthesia and it was suggested that theta and alpha wavespropagationcouldberelatedtotheprocessesparticipatinginthewakefulnesscontrol.DataobtainedwithDTFmethodwerecomparedwithdatareceivedfromtheanalysisofcerebralbloodflowwiththeuse of PET in other laboratory. This study showed that analysis of the EEG signal propagation isuseful for better understanding and thus safer induction of anaesthesia procedure.