Evaluation of the Applicability and Reliability of the Mid-Latency Auditory Evoked Potentials derived aepEX* as a Measure of Anaesthetic Depth in Paediatric Patients

Assessment of depth of hypnosis (DoH) during general anaesthesia has become
increasingly popular during the last decade in both adult and paediatric
patients. The currently available monitoring devices all work with internal
algorithms based on adult encephalogram (EEG) data. Since the EEG of a child
significantly differs from that of an adult, the reliability of EEG-derived DoH
devices in children is needs to be specifically addressed.
With respect to the ability to predict reactions to specific external stimuli
mid-latency auditory evoked potentials (MLAEP) appear to be superior to
processed raw-EEG variables. Like the raw-EEG, MLAEP also develop over a period
extending the first decade of life. Thus paediatric evaluation and validation
of DoH-monitoring systems based on adult MLAEP data is mandatory before they
can be introduced into clinical practice. Simultaneous BIS-registration will
enable us to compare the performance of the aepEX to another established DoH
index.

The aepEX monitor provides a DoH index based on (adult) MLAEP values. The aim
of this observational study is to evaluate the performance of the aepEX as a
measure of DoH in children.

Single centre, prospective observational study

aepEX/BIS monitoring is applied to children who undergo elective surgery under
general anaesthesia with propofol, sevoflurane and desflurane. Besides aepEX
monitoring the patients* vigilance / level of hypnotic depth will be assessed
intermittently by means of the UMSS.

All data analyses will be performed off-line after completion of the patient
related part of the study.

The ability of the aepEX* and other indicators (Propofol-, sevoflurane- and
desflurane-concentration, Heart Rate, Blood Pressure, BIS) to describe DoH will
be assessed using Prediction Probability (PK) Analysis. PK analysis has been
established in anaesthesia to compare the performance of indicators of DoH
having different units of measurement.

The effects of different propofol-, sevoflurane-, and desflurane-concentrations
on the aepEX, the BIS, the UMSS and hemodynamic variables will be assessed by
means of general-linear-models analyses.

Participants of the study undergo surgical procedures under general
anaesthesia. The common anaesthesia risk-factors are not affected by the study.
The only additional theoretical risk is that of a mild skin irritation caused
by the standard ECG electrodes used for MLAEP registration and the
BIS-electrode. We have been using these electrodes for several years now
without problems.
Nonetheless this issue has been added to the patient information folder as a
possible side effect.