Single sweep analysis of event related auditory potentials for the monitoring of sedation in cardiac surgery patients

Event-related potentials (ERPs) from the auditory system were investigated in 28 post-operative cardiac patients in order to assess their relevance in the monitoring of patient sedation level. Midazolam (17 patients) and prop ofol (11 patients) were the sedative agents used. The auditory ERP componen ts of N100 (HAB100) and mismatch negativity (MMN) were considered. A single sweep method based on the AutoRegressive with eXogenous input (ARX) model, which is able to enhance the evoked responses to each, single stimulus, wa s used to process each sweep and to compute traditional parameters on a swe ep-by-sweep basis. Differences in the measured parameters were related to v ariations in the patient sedation levels classified through Ramsay score. S ignificant differences (P < 0.05) in both MMN and HAB100 parameters were fo und between light sedation (LS) and deep sedation (DS) levels. (C) 2000 Els evier Science Ireland Ltd. All rights reserved.