Role of auditory evoked potential index in monitoring anesthesia depth

Objective To study the role of auditory evoked potential index (AAI) in monitoring anesthesia depth during anesthesia maintained with propofol target-controlled influsion(TCI) or isoflurane inhalation. Methods Thirty-three ASA class I patients scheduled for selective laparoscopic cholecystectomy (LC) were randomly allocated to two groups. Group I(n=18): anesthetized with inhalation of isoflurane and nitrous oxide,and Group P(n=15): anesthetized with propofol TCI and nitrous oxide inhalation. The concentration of isoflurane inhalation or propofol TCI was adjusted to keep the MAP,HR within the range of 20% the basic levels. The end-tidal concentration of isoflurane,TCI concentration of propofol and the AAI values were recorded. Results The values of AAI were all lower with a transient AAI ≤10 12 times in the group P and 4 times in the group I. The values of AAI were negatively correlated with the concentration of propofol TCI and the end-tidal concentration of isoflurane (P0.05),but had no correlation with MAP and HR. Conclusion AAI monitoring combined with other parameters can reflect the depth of general anesthesia more sufficiently.