Comparison between cerebral state index and bispectral index as measures of electroencephalographic effects of sevoflurane using combined sigmoidal Emax model

Abstract

Aim:The cerebral state index (CSI) was recently introduced as an electroencephalographic monitor for measuring the depth of anesthesia. We compared the performance of CSI to the bispectral index (BIS) as electroencephalographic measures of sevoflurane effect using two combined sigmoidal E max models. Methods: Twenty adult patients scheduled for laparotomy were studied. After induction of general anesthesia, sevoflurane concentrations were progressively increased and then decreased over 70 min. An analysis of the BIS and CSI with the sevoflurane effect-site concentration was conducted using two combined sigmoidal E max models. Results: The BIS and CSI decreased over the initial concentration range of sevoflurane and then reached a plateau in most patients. A further increase in sevoflurane concentration produced a secondary plateau in the pharmacodynamic response. The CSI was more strongly correlated with effect-site sevoflurane concentration (R 2 =0.95±0.04) than the BIS was (R 2 =0.87±0.07) (P<0.05). The individual E max and C eff50 (effect-site concentration associated with 50% decrease from baseline to plateau) values for the upper and lower plateaus were significantly greater for BIS (12.7±7.3, 1.6±0.4, and 4.2±0.5, respectively) than for CSI (3.4±2.2, 1.2±0.4, and 3.8±0.5, respectively) (P<0.05). The remaining pharmacodynamic parameters for the BIS and CSI were similar. Conclusion: The overall performance of the BIS and CSI during sevoflurane anesthesia was similar despite major differences in their algorithms. However, the CSI was more consistent and more sensitive to changes in sevoflurane concentration, whereas the measured BIS seemed to respond faster. The newly developed combined E max model adequately described the clinical data, including the pharmacodynamic plateau.

Correlation of Sedline-generated variables and clinical signs with anaesthetic depth in experimental pigs receiving propofol

“…In previous publications [ 24 , 28 , 29 ], an inhibitory sigmoidal model was used to describe the relationship between PSI and propofol dose in humans. However, other investigations performed under inhalant anaesthesia found that the dose-effect relationship of EEG-derived variables obtained from BIS and Narcotrend devices was better described with the combination of two fractional sigmoid E max models [ 26 , 27 , 30 , 31 ]. The same observation was made for PSI in pigs undergoing propofol anaesthesia in the present study.…”

“…In the present investigation, the plateau was observed at PSI value of 44 (E max 2 = 44.2), which falls within the range generally targeted during surgical anaesthesia in humans (25–50). Former studies reported a plateau at around 40 for BIS and 50 for Narcotrend [ 26 , 27 , 30 , 31 ]. The value at which these indexes will tend to display a plateau over the range of anaesthetic doses tested depends on the computation algorithm, which is proprietary and often not published.…”

Evaluating NeuroSENSE for assessing depth of hypnosis during desflurane anesthesia: an adaptive, randomized-controlled trial

“…A similar plateau effect was reported for desflurane using BIS and Narcotrend 25 and for sevoflurane using BIS and Cerebral State Monitor (Danmeter A/S, Odense, Denmark). 26 In a secondary analysis following a large 1,100-patient cohort study (B-Unaware trial), 27 Whitlock et al found a -15.4 unit change (95% CI, -17.8 to -13.1) for every 1 MAC change in the 0.42-1.51 MAC range using the BIS monitor; yet, when the authors excluded patients with extreme values, this reduced to -8.6 unit per 1 MAC change.…”

Comparison between cerebral state index and bispectral index during desflurane anesthesia

“…CSI uses an algorithm different from that used for BIS. It has four sub-parameters derived from time domain analysis (burst-ratio) and frequency domain analysis (α-ratio, β-ratio, and β-ratio-α-ratio) of EEG [ 4 ].…”