Comparison between Bispectral Index and Patient State Index as Measures of the Electroencephalographic Effects of Sevoflurane

Background: The Bispectral Index (BIS) and the Patient State Index (PSI) quantify depth of anesthesia by analyzing the electroencephalogram. The authors examined the response of BIS and PSI to sevoflurane anesthesia. Methods: In 22 patients, sevoflurane anesthesia was induced by inhalation with a tight-fitting facemask and was maintained via a laryngeal mask. Sevoflurane concentrations were increased until burst suppression occurred and subsequently decreased until BIS recovered to values above 60. This procedure was repeated twice until patients underwent intubation for subsequent surgery. End-tidal sevoflurane concentrations, BIS, and PSI were recorded simultaneously. The performance of PSI and BIS to predict the estimated sevoflurane effect site concentration, as derived from simultaneous pharmacokinetic and pharmacodynamic modeling, was compared by determination coefficients (&rgr;2) and prediction probabilities (PK). Results: A significant (P < 0.001) correlation between BIS and PSI was found (r2 = 0.75), and a close sigmoid relation between sevoflurane effect site concentration and both BIS (&rgr;2 = 0.84 ± 0.09) and PSI (&rgr;2 = 0.85 ± 0.15) was observed. The maximum sevoflurane electroencephalographic effect resulted in PSI values (1.3 ± 4.3) that were significantly (P = 0.019) lower than BIS values (7.9 ± 12.1), and the effect site efflux constant ke0 was significantly smaller (P = 0.001) for PSI (0.13 ± 0.08 min−1) than for BIS (0.24 ± 0.15 min−1). The probability of BIS (PK = 0.80 ± 0.11) to predict sevoflurane effect site concentration did not differ (P = 0.76) from that of PSI (PK = 0.79 ± 0.09). Conclusions: The BIS reacted faster to changes in sevoflurane concentrations, whereas the PSI made better use of the predefined index range. However, despite major differences in their algorithms and minor differences in their dose–response relations, both PSI and BIS predicted depth of sevoflurane anesthesia equally well.

[1]  Erik Olofsen,et al.  The Influence of Remifentanil on the Dynamic Relationship between Sevoflurane and Surrogate Anesthetic Effect Measures Derived from the EEG , 2002, Anesthesiology.

[2]  E. Kochs,et al.  Time Delay of Index Calculation: Analysis of Cerebral State, Bispectral, and Narcotrend Indices , 2006, Anesthesiology.

[3]  C. Minto,et al.  Effect-site half-time for burst suppression is longer than for hypnosis during anaesthesia with sevoflurane. , 2008, British journal of anaesthesia.

[4]  R. Chabot,et al.  Patient state index. , 2002, Best practice & research. Clinical anaesthesiology.

[5]  Lewis B. Sheiner,et al.  The NONMEM System , 1980 .

[6]  J. Bruhn,et al.  Spectral Entropy and Bispectral Index as Measures of the Electroencephalographic Effects of Propofol , 2006, Anesthesia and analgesia.

[7]  I. Rampil.  A Primer for EEG Signal Processing in Anesthesia , 1998, Anesthesiology.

[8]  Andreas Hoeft,et al.  Spectral Entropy and Bispectral Index as Measures of the Electroencephalographic Effects of Sevoflurane , 2004, Anesthesiology.

[9]  L B Sheiner,et al.  Simultaneous modeling of pharmacokinetics and pharmacodynamics: application to d-tubocurarine. , 1980, Clinical pharmacology and therapeutics.

[10]  J. R. Sneyd,et al.  Effect site: who needs it? , 2007, British journal of anaesthesia.

[11]  N. T. Smith,et al.  Performance of the ARX-derived Auditory Evoked Potential Index as an Indicator of Anesthetic Depth: A Comparison with Bispectral Index and Hemodynamic Measures during Propofol Administration , 2002, Anesthesiology.

[12]  C. Lennmarken,et al.  Awareness during anaesthesia: a prospective case study , 2000, The Lancet.

[13]  Warren D. Smith,et al.  Measuring the Performance of Anesthetic Depth Indicators , 1996, Anesthesiology.

[14]  P. White,et al.  Is the Patient State Analyzer with the PSArray2 a Cost-Effective Alternative to the Bispectral Index Monitor During the Perioperative Period? , 2004, Anesthesia and analgesia.

[15]  J. Bruhn,et al.  Application of Bispectral Index® and Narcotrend® Index to the Measurement of the Electroencephalographic Effects of Isoflurane with and without Burst Suppression , 2004, Anesthesiology.

[16]  Leslie S. Prichep,et al.  Patient State Index: Titration of Delivery and Recovery from Propofol, Alfentanil, and Nitrous Oxide Anesthesia , 2002, Anesthesiology.

[17]  A. Hill,et al.  The possible effects of the aggregation of the molecules of haemoglobin on its dissociation curves , 1910 .

[18]  S L Shafer,et al.  A comparison of spectral edge, delta power, and bispectral index as EEG measures of alfentanil, propofol, and midazolam drug effect , 1997, Clinical pharmacology and therapeutics.

[19]  J. Bruhn,et al.  Depth of anaesthesia monitoring: what's available, what's validated and what's next? , 2006, British journal of anaesthesia.

[20]  R. Duclaux,et al.  EEG bispectral index and hypnotic component of anaesthesia induced by sevoflurane: comparison between children and adults. , 2001, British journal of anaesthesia.

[21]  E R John,et al.  The Patient State Index as an indicator of the level of hypnosis under general anaesthesia. , 2004, British journal of anaesthesia.

[22]  M. Zwarts,et al.  Multi-level approach to anaesthetic effects produced by sevoflurane or propofol in humans: 1. BIS and blink reflex. , 2007, British journal of anaesthesia.

[23]  S. Shafer,et al.  Application of semilinear canonical correlation to the measurement of opioid drug effect , 1992, Journal of Pharmacokinetics and Biopharmaceutics.

[24]  E. Kochs,et al.  Detection of awareness in surgical patients with EEG-based indices--bispectral index and patient state index. , 2003, British journal of anaesthesia.

[25]  P. White,et al.  A Comparison of Patient State Index and Bispectral Index Values During the Perioperative Period , 2002, Anesthesia and analgesia.

[26]  K. Uutela,et al.  Surgical stress index reflects surgical stress in gynaecological laparoscopic day-case surgery. , 2007, British journal of anaesthesia.

[27]  Patient State Index (PSI) measures depth of sedation in intensive care patients , 2004, Intensive Care Medicine.

[28]  L B Sheiner,et al.  Estimating population kinetics. , 1982, Critical reviews in biomedical engineering.

[29]  E Kochs,et al.  EEG-based indices of anaesthesia: correlation between bispectral index and patient state index? , 2004, European journal of anaesthesiology.