Changes of auditory stimulus processing in sevoflurane-induced sedation.

Despite the widespread use in clinical practice, little research has been done on mechanisms of sedation. In particular, little is known about the changes in the information processing of external stimuli in sedation. The aim of this study was to investigate the changes of event-related potential (ERP) in auditory passive oddball paradigm when the sedation was induced by sevoflurane inhalation. Electroencephalography (EEG) measurements were obtained for each subject using 32-channel EEG recording devices. Sevoflurane was administered at an initial concentration of 0.8 vol% to induce sedative state. Auditory stimulation based on the passive oddball paradigm was delivered to the subject via an earphone before and after sevoflurane administration. After ERP was extracted from the measured EEG, the topographic distribution of ERP, the temporal changes of ERP in each channel, and the statistical difference in ERP between awake and sedation were analyzed. In the awake state, P300 was observed at 320-360 ms latency, and P300 was concentrated in the frontal and central area. P300 amplitude was significantly decreased in sedation compared to awake. Sevoflurane-induced sedation caused a decrease in P300 amplitude. This result may reflect the weakening of the cognitive function governing attentional process and stimuli discrimination during sedation.