Prediction of depth of sedation and anaesthesia by the Narcotrend EEG monitor.
BACKGROUND
The Narcotrend (Monitor Technik, Bad Bramstedt, Germany) assesses sedation by automatic classification of EEG signals, using a scale first used for visual evaluation of the EEG. Limited information is available on its value, and only a few studies of the method exist. We set out to study the performance of the Narcotrend during propofol sedation.


METHODS
In 23 ASA I-II patients, aged 18-65 yr, about to have general anaesthesia, we induced anaesthesia in steps using a target-controlled infusion of propofol. After equilibration for 8 min at each predicted propofol concentration (0.5, 1.0, 2.0, 3.0 and 4.0 microg x ml(-1)), sedation was assessed clinically with the modified Observer's Assessment of Alertness/Sedation Scale and the Narcotrend stage was noted. The prediction performance of the Narcotrend was assessed with the prediction probability P(K). A P(K) value of 1.0 means an exact prediction on every occasion, while a P(K) of 0.5 is no better than a 50:50 chance of being correct.


RESULTS
In 12 women and 11 men (age 42 (sd 11) yr), a total of 138 measurements were made; 129 were analysed and nine were of poor signal quality. The prediction probability for the corresponding level of sedation was P(K)=0.92 (se 0.01); for the different target concentrations of propofol it was P(K) = 0.91 (se 0.01).


CONCLUSIONS
The Narcotrend can monitor sedation with propofol. Other sedatives, anaesthetics and opioids should be used to test this monitor.
Bauerle
K
K
Klinik und Poliklinik für Anästhesiologie, Universitätsklinikum Würzburg, Zentrum operative Medizin, Oberdürrbacher Strasse 6, D-97080 Würzburg, Germany. kerstinbauerle@gmx.de
Greim
C-A
CA
Schroth
M
M
Geisselbrecht
M
M
Köbler
A
A
Roewer
N
N
D000328:Adult; D000771:Anesthesia, Intravenous; D018686:Anesthetics, Intravenous / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D016292:Procedural Sedation; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography / Q000187:drug effects*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000295:instrumentation* / Q000379:methods; D015742:Propofol / Q000494:pharmacology
D018686:Anesthetics, Intravenous; D015742:Propofol