title: Validation of the alfentanil canonical univariate parameter as a measure of opioid effect on the electroencephalogram.
abstract: BACKGROUND
  Several parameters derived from the multivariate electroencephalographic (EEG) signal have been used to characterize the effects of opioids on the central nervous system. These parameters were formulated on an empirical basis. A new statistical method, semilinear canonical correlation, has been used to construct a new EEG parameter (a certain combination of the powers in the EEG power spectrum) that correlates maximally with the concentration of alfentanil at the effect site. To date, this new canonical univariate parameter (CUP) has been tested only in a small sample of subjects receiving alfentanil.
  
  
  METHODS
  The CUP was tested on EEG data from prior studies of the effect of five opioids: alfentanil (n = 5), fentanyl (n = 15), sufentanil (n = 11), trefentanil (n = 5), and remifentanil (n = 8). We compared the CUP to the commonly used EEG parameter spectral edge, SE95%. The comparison was based on the signal to noise ratio, obtained by fitting a nonlinear pharmacodynamic model to both parameters. The pharmacodynamic parameter estimates obtained using both measurements were also compared.
  
  
  RESULTS
  The values for signal-to-noise ratio were significantly greater for the CUP than for SE95% when considering all the opioids at once. The pharmacodynamic estimates were similar between the two EEG parameters and with previously published results. Semilinear canonical correlation coefficients estimated within each drug group showed patterns similar to each other and to the coefficients in the CUP, but different from coefficients for propofol and midazolam.
  
  
  CONCLUSIONS
  Although the CUP was originally designed and tested using alfentanil, we have proven it to be a general measure of opioid effect on the EEG.
authors.affiliation: Anesthesia Department, Stanford University, School of Medicine, California, USA.
authors.forename: P L
authors.initials: PL
authors.lastname: Gambús
authors.forename: K M
authors.initials: KM
authors.lastname: Gregg
authors.forename: S L
authors.initials: SL
authors.lastname: Shafer
mesh_terms: D015760:Alfentanil / Q000494:pharmacology*; D000701:Analgesics, Opioid / Q000494:pharmacology*; D004569:Electroencephalography / Q000187:drug effects*; D006801:Humans
chemical_list: D000701:Analgesics, Opioid; D015760:Alfentanil