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Published on: December 6, 2016
The dynamic relationship between end-tidal sevoflurane concentrations, bispectral index, and cerebral state index in
Ricardo Fuentes1, Luis I Cortínez, Michel M R F Struys
1Departamento de Anestesiología, Hospital Clínico U. Católica, Marcoleta 367, Santiago, Chile.
Insights
Electroencephalogram (EEG) monitors like the cerebral state index (CSI) and bispectral index (BIS) show different dynamic profiles for sevoflurane in children. The CSI demonstrated a slower rate of change in anesthetic effect compared to BIS.
Area of Science:
- Anesthesiology
- Neuroscience
- Pediatric Medicine
Background:
- Electroencephalogram (EEG) monitoring is crucial for guiding anesthetic administration in children.
- Characterizing the dynamic effects of anesthetics like sevoflurane using EEG monitors is essential for this population.
Purpose of the Study:
- To quantify and compare the dynamic profile of sevoflurane's hypnotic effect as measured by the cerebral state index (CSI) and bispectral index (BIS) in pediatric patients.
- To evaluate the pharmacodynamic differences between CSI and BIS in response to sevoflurane in children.
Main Methods:
- Prospective study of 15 healthy children (aged 3-15 years) undergoing minor surgery.
- Simultaneous recording of CSI and BIS during sevoflurane administration with decreasing end-tidal concentrations.
- Pharmacokinetic/pharmacodynamic (PK/PD) modeling to characterize C(ET)-sevoflurane effect-site concentration equilibration and hypnotic effects.
Main Results:
- The effect-site equilibration half-life (t(1/2) k(e0)) for sevoflurane was significantly slower with CSI (2.0 min) compared to BIS (1.2 min) (P < 0.05).
- Maximum hypnotic effect (E(max)) was higher with CSI (45) than BIS (27) (P < 0.05), while sensitivity (C(50)) was similar (P > 0.05).
- Population prediction error was significantly better for BIS (-0.7 +/- 26.9) than CSI (-3.0 +/- 178.6) (P < 0.05).
Conclusions:
- The dynamic profile and pharmacodynamics of sevoflurane in children are monitor-dependent, with CSI showing a slower response rate.
- These differences in hypnotic effect quantification between CSI and BIS must be considered for effective anesthetic guidance in pediatric patients.
- Further research may be needed to optimize the use of these EEG monitors in pediatric anesthesia.
Background:
To guide anesthetic administration with electroencephalogram monitors in children, an adequate characterization of the anesthetic effect measured by these monitors in this population is needed. We sought to quantify and compare the dynamic profile of sevoflurane's effect measured with the cerebral state index (CSI) and the bispectral index (BIS) in children.
Methods:
Fifteen healthy children, aged 3-15 yr, scheduled to undergo minor surgery were prospectively studied. During the simultaneous recording of CSI and BIS, the sevoflurane vaporizer was set at 6 vol % for 5 min and then decreased. End-tidal concentrations (C(ET)) were measured. The C(ET)-sevoflurane effect-site concentration equilibration and pharmacodynamics were modeled. Goodness of fit between models was compared. Data are typical value (coefficient of variation).
Results:
Within the anesthetic depth range studied, the rate of change of sevoflurane's effect expressed as the effect-site equilibration half-life (t(1/2) k(e0)) was slower with the CSI [2.0 (14) min] than with BIS [1.2 (53) min] (P < 0.05). The estimated baseline effect of BIS and CSI before sevoflurane administration (E(0)) was 84 (39) for CSI and 87 (7) for BIS (NS). The sensitivity to sevoflurane hypnotic effect expressed in the C(50) [steady-state C(ET) eliciting half of the maximum response (E(max))] was 2.1 (68) % with CSI and 2.1 (16)% with BIS (NS). The E(max) with CSI 45 (0) was higher than that with BIS 27 (39) (P < 0.05). The population prediction error was significantly better for BIS (-0.7 +/- 26.9) than for CSI (-3.0 +/- 178.6) (P < 0.05).
Conclusions:
In children, the t(1/2) k(e0) of sevoflurane and the pharmacodynamics of sevoflurane were quantified and the results were entirely dependent on the monitor used to measure its hypnotic effect. Within the anesthetic depth range studied, the rate of change of sevoflurane's effect was slower with the CSI. To adequately guide sevoflurane administration with these monitors in children, these differences should be considered.
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