An electroencephalographic comparison of alfentanil with other narcotics and with thiopental.

Using aperiodic analysis, we compared the EEG produced by alfentanil with the EEGs produced by two other opiates--fentanyl and sufentanil--on the one hand and with the EEG produced by a barbiturate--thiopental--on the other hand. Alfentanil and thiopental were injected over 1 minute; fentanyl and sufentanil were injected over 10 to 15 minutes. From the aperiodic analysis we derived up to seven single-number variables computed over 30- or 60-second epochs. All the opiates induced EEGs that were qualitatively similar to each other, although the maximum or minimum values tended to be greater and the time course more rapid with alfentanil than with the other two opiates. This finding may have been related to the fact that we injected relatively more alfentanil and administered it more rapidly. The EEGs produced by alfentanil and thiopental differed markedly, both qualitatively and quantitatively. The total power at 1 Hz and cumulative power at 3 Hz went to higher peak values with alfentanil, the latter tending to decrease with thiopental. The total number of waves per epoch went to lower peak values with alfentanil; there was little change with thiopental. The frequency below which 90% of the power resides went to considerably lower peak values with alfentanil than with thiopental. Finally, total power at 10 to 12 Hz (alpha waves) and average power at 17 to 19 Hz (beta waves) went to very high peak values with thiopental, but decreased with alfentanil.(ABSTRACT TRUNCATED AT 250 WORDS)