Correlation between bispectoral index and predicted effect-site concentration of propofol in different levels of target-controlled, propofol induced sedation in healthy volunteers.
BACKGROUND
Bispectral Index is an objective tool to assess electroencephalographic activity and measure the effect of certain sedatives and hypnotics on the brain. In addition, there are certain subjective tools such as the observer's assessment of alertness and sedation which are used. The correlation between BIS and the concentration of propofol in the brain, and the relationship between these subjective and objective tools in assessing sedation levels are the subject of this study.


METHODS
Thirty healthy volunteers enrolled in this prospective observational study. They were sedated with a target controlled infusion of propofol with an initial target of 0.8 microg.mL(-1)and an increase in target to 0.2 microg.mL(-1) ten minutes after equilibration of the predicted and set target concentrations. In each sedation score, the Bispectral Index value and predicted effect site concentration of propofol were recorded and analyzed. Analysis of variance and significant differences between groups were analyzed by paired t-test. Correlations between Bispectral Index and effect site concentration of propofol at each sedation score and the relationship of BIS and effect site concentration of propofol to each sedation score were assessed and analyzed by nonparametric Spearman's rho.


RESULTS
The means of Bispectral Index and effect site concentration of propofol at each sedation score showed a significant difference with the following score. Additionally, Bispectral Index and effect site concentration of propofol showed a significant negative correlation in sedation scores 3 and 2 when inducing sedation. In other sedation scores or when reversing the sedation, no strong correlation was noted.


CONCLUSIONS
Both Bispectral Index and effect site concentration of propofol indicate a good estimate of sedation levels; however their correlations are significant and negative only at moderate and deep sedation levels, and during the induction of sedation.
Yeganeh
Naser
N
Department of Anesthesiology and Intensive Care, Imam Reza Hospital, Kermanshah University of Medical Sciences, Kermanshah, Iran. nyeganeh@kums.ac.ir
Roshani
Bahman
B
Almasi
Afshin
A
Jamshidi
Nasim
N
D000328:Adult; D016292:Procedural Sedation / Q000523:psychology / Q000592:standards; D056805:Consciousness Monitors; D054810:Deep Sedation / Q000523:psychology / Q000592:standards; D004569:Electroencephalography; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D015742:Propofol / Q000494:pharmacology*; D055815:Young Adult
D006993:Hypnotics and Sedatives; D015742:Propofol