title: Patient State Index (PSI) measures depth of sedation in intensive care patients.
abstract: OBJECTIVE
  To investigate whether the electroencephalogram (EEG)-based Patient State Index (PSI) indicates the level of sedation as measured by Ramsay score in intubated and mechanically ventilated patients in the ICU.
  
  
  METHODS
  Prospective, single-blinded observer study.
  
  
  METHODS
  Surgical intensive care unit.
  
  
  METHODS
  Forty-one consecutive adult patients requiring intubation and ventilation during intensive care therapy.
  
  
  RESULTS
  Following skin preparation with alcohol and placement of EEG electrodes, PSI was recorded while patients were ventilated and sedated with constant drug infusion rates. After 30 min, the level of sedation was measured by an assessor, who was blinded to PSI values, using the Ramsay sedation score. For analysis, the mean of PSI values measured during the last minute before clinical assessment of sedation was calculated. General Linear Model (GLM) analysis revealed significant differences between the PSI values at different levels of sedation as measured by the Ramsay score, except for the differentiation of level 5 from levels 4 and 6 (p>0.3) and level 2 from level 3, where only a trend was reached (p=0.077). The prediction probability of PSI was 0.920+/-0.037.
  
  
  CONCLUSIONS
  As the high prediction probability and the analysis of paired comparisons suggest, PSI may be used to quantify the level of propofol/sufentanil sedation in ICU patients. Further studies are required to test whether these promising results can be verified for other drug combinations.
authors.affiliation: Department of Anaesthesiology, Technische Universität München, Klinikum rechts der Isar, Ismaningerstrasse 22, 81675, Munich, Germany. Gerhard.Schneider@LRZ.tum.de.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Schneider
authors.affiliation: Department of Anaesthesiology, Technische Universität München, Klinikum rechts der Isar, Ismaningerstrasse 22, 81675, Munich, Germany.
authors.forename: Susanne
authors.initials: S
authors.lastname: Heglmeier
authors.affiliation: Department of Anaesthesiology, Technische Universität München, Klinikum rechts der Isar, Ismaningerstrasse 22, 81675, Munich, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Schneider
authors.affiliation: Department of Anaesthesiology, Technische Universität München, Klinikum rechts der Isar, Ismaningerstrasse 22, 81675, Munich, Germany.
authors.forename: Gunter
authors.initials: G
authors.lastname: Tempel
authors.affiliation: Department of Anaesthesiology, Technische Universität München, Klinikum rechts der Isar, Ismaningerstrasse 22, 81675, Munich, Germany.
authors.forename: Eberhard F
authors.initials: EF
authors.lastname: Kochs
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003422:Critical Care; D016903:Drug Monitoring; D004569:Electroencephalography / Q000379:methods; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage*; D007362:Intensive Care Units; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic; D011446:Prospective Studies; D016037:Single-Blind Method
chemical_list: D006993:Hypnotics and Sedatives