Electroencephalographic Bicoherence Is Sensitive to Noxious Stimuli during Isoflurane or Sevoflurane Anesthesia

Abstract

Noxious stimuli decreased the peak heights of electroencephalographic bicoherence, an effect that was counteracted by fentanyl analgesia.

Pentazocine increases bispectral index without surgical stimulation during nitrous oxide–sevoflurane anesthesia

“…pentazocine, given as a 0.3 mg/kg bolus before surgery under nitrous oxide-sevoflurane anesthesia, provoked a statistically significant increase in BIS values, in contrast previous reports on the effects of other opioids [1,2]. In a preliminary study involving eight patients in which 1% sevoflurane alone was inhaled, we also observed a significant increase (from 49.3 ± 5.8 at baseline to 64.9 ± 2.8 at 15 min from baseline) in the BIS values following i.v.…”

“…Many investigators have reported that opioids produce minimal changes in bispectral index (BIS) values in the absence of painful stimulation [1,2] but that the addition of opioids to anesthetics does affect BIS values when a painful stimulus is applied. However, despite the large number of published reports on the effects of mu opioids, such as fentanyl and remifentanil, on the BIS during general anesthesia [1,2], no comparative studies on pentazocine, a kappa agonist, versus fentanyl, a mu agonist, on the BIS values have been reported.…”

“…However, despite the large number of published reports on the effects of mu opioids, such as fentanyl and remifentanil, on the BIS during general anesthesia [1,2], no comparative studies on pentazocine, a kappa agonist, versus fentanyl, a mu agonist, on the BIS values have been reported. Consequently, we have compared the effect of pentazocine and fentanyl on BIS values during nitrous oxide-sevoflurane anesthesia without surgical stimulation.…”

“…The BIS was monitored using an XP monitor (model A-XP; Aspect Medical Systems, Natick, MA) equipped with an electrode BIS Quatro (Aspect Medical Systems, Newton, MA) that was placed on the forehead of the patient. During part of our study, the raw EEG signal was recorded on a personal computer using the Bispectrum Analyzer BIS A2000 version (BSA Ver3.22B2) [2].…”

Bispectral analysis gives us more information than power spectral-based analysis

“…We have also shown that we can obtain other facts from phase information. 4 Bispectral analysis would have given more information than power spectral-based analysis, if the authors had used the EEG recorded from unilateral leads.…”