title: The Narcotrend monitor and the electroencephalogram in propofol-induced sedation.
abstract: BACKGROUND
  The Narcotrend (NCT) is a one-channel electroencephalogram (EEG) monitor of the level of sedation. It is based on a visual EEG scoring system, which was developed by Loomis and modified by Kugler, to yield a visual expert classification (VEC) scheme for differentiation of six levels of sedation (A-F), which are subdivided into 16 substages. We designed the present study to test whether results of the automated classification of one-channel NCT input reflect those from VEC of five-channel EEG.
  
  
  METHODS
  Twelve healthy male volunteers received propofol using two different infusion regimens in a randomized, crossover design with concomitant NCT monitoring and VEC. Scoring results of NCT were compared with those of VEC.
  
  
  RESULTS
  During the infusion period, score differences of more than three substages were observed in 14 of 24 (= 58%) propofol administrations (4%-7% of total data). Often, the NCT indicated lighter sedation than VEC, which revealed more delta activity from nonfrontal leads. During recovery, NCT reported deeper sedation than VEC in 6 of 24 (= 25%) propofol administrations. Discordant trends (periods of at least five subsequent epochs with monotonic, but opposite trends for both NCT and VEC) were noted in 9 of 24 propofol administrations (37%). Furthermore, NCT had several periods when no staging information was displayed, varying from a few seconds to 10 min.
  
  
  CONCLUSIONS
  As the algorithm of NCT is proprietary and not accessible to the public, reasons for the observed differences between NCT and VEC cannot be analyzed and explanations must remain speculative.
authors: Institute for Anesthesiology, Ludwig Maximilians University, Munich, Germany. doenickeaw@aol.com
authors: Alfred W
authors: AW
authors: Doenicke
authors: Johann
authors: J
authors: Kugler
authors: Eberhard
authors: E
authors: Kochs
authors: Jeus
authors: J
authors: Rau
authors: Haraed
authors: H
authors: Mückter
authors: Rainer
authors: R
authors: Hoernecke
authors: Peter
authors: P
authors: Conzen
authors: Harry
authors: H
authors: Bromber
authors: Gerhard
authors: G
authors: Schneider
mesh_terms: D000293:Adolescent; D000328:Adult; D016292:Procedural Sedation; D004569:Electroencephalography / Q000295:instrumentation; D005072:Evoked Potentials, Auditory; D006801:Humans; D006993:Hypnotics and Sedatives; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation; D015742:Propofol
chemical_list: D006993:Hypnotics and Sedatives; D015742:Propofol