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Comparison of BIS and AEP indices for monitoring hypnotic level during sevoflurane anaesthesia

Jensen, E. W.1; Litvan, H.2; Caminal, P.1; Fernandez, J. A.2; Maestre, M. L.2

European Journal of Anaesthesiology: 2000 - Volume 17 - Issue - p 20
European Society of Anaesthesiologists; 8th Annual Meeting with the Austrian International Congress; Vienna, Austria, 1-4 April 2000

1Department of Cardiac Anaesthesia, Hospital Sant Pau, Barcelona, Spain.

2Polytechnic University of Catalonia, Department ESAII, CREB, Spain

    Abstract A-64

    Background: The bispectral analysis of the EEG (BIS) and Middle Latency Auditory Evoked Potentials and their derived indices are both described as good correlates to the hypnotic level during non receptor specific anaesthesia. In this study we have compared the two methods with respect to the following two output variables. 1) Time from loss of consciousness (LOC) until the AEP-index was below 28 and the BIS was below 60. 2) Time from recovery of consciousness (ROC) until the AEP index was above 40 and BIS above 70. FIGURE

    Figure 1

    Figure 1

    Materials and methods: The study was approved by the local ethics committee and data were collected from 12 patients scheduled for cardiac surgery. Induction of anaesthesia was carried out with eight per cent sevoflurane. The AEP was recorded using the A-line AEP-monitor (Danmeter, Odense, Denmark) and the BIS was recorded using the A-2000 BIS monitor (Aspect Medical, Ma, USA). Sevoflurane was administered until LOC, defined as loss of a meaningful response to a verbal command. The gas was closed and the patient was allowed to awake and ROC was registered.

    Results and discussion: During induction the AEP index descended to 28 within a mean (SD) time of 47(41) s after LOC and the BIS reached 60 after 63(47) s (no significant difference). During the transition from asleep to awake the AEP index was above 40 on average (SD) 9(6) s after ROC and the BIS index was above 70 within a mean (SD) time 24(8) s after ROC.

    Conclusion: Both the AEP-index and the BIS correlated well to LOC and ROC. The AEP index was significantly faster in detecting the transition from asleep to awake.

    Section Description

    The abstracts published in this supplement have been typeset from camera-ready copies prepared by the authors. Every effort has been made to reproduce faithfully the abstracts as submitted. However, no responsibility is assumed by the organisers for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of methods, products, instructions or ideas contained in the material herein. Because of the rapid advances in medical sciences, we recommend that independent verification of diagnoses and drug doses should be made.

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    © 2000 European Society of Anaesthesiology