The Influence of Age on the Dynamic Relationship Between End-Tidal Sevoflurane Concentrations and Bispectral Index

Abstract

BACKGROUND:Age is an important determinant of the pharmacokinetic profile of inhaled anesthetics. The influence of age on the dynamic profile of sevoflurane's effect has not been well described. We performed this study to characterize the influence of age and other covariates on the dynamic relationship between sevoflurane end-tidal concentration (C ET ) and its effect measured by bispectral index (BIS). METHODS: Fifty patients, aged 3-71 yr, scheduled for minor surgery were prospectively studied. The BIS and sevoflurane C ET were continuously measured during the study period. During maintenance of anesthesia and after stable BIS values of 60 -65 were obtained, the inspired concentration of sevoflurane was increased to 5 vol % for 5 min or until BIS Ͻ40 and then decreased. The dynamic relationship between sevoflurane C ET and its effect as measured by BIS during this transition period were modeled with an inhibitory E max model using a population pharmacokinetic-pharmacodynamic approach with NONMEM V. A predictive check method was used to validate the final model. RESULTS: The sensitivity to sevoflurane's effect as measured by BIS expressed in the C 50 [steady-state C ET eliciting half of maximum response (I max )] increased with age. The speed of change of sevoflurane's effect, expressed as the effect-site equilibration half-life (t 1/2 k e0 ), increased at older ages. The predictive check analysis confirmed the adequacy of the model. CONCLUSIONS: Age significantly affects the dynamic relationship between sevoflurane C ET and its effect measured with BIS.

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

“…The k e0 was faster with the BIS than with the CSI, although the two values were not statistically different. Our results were similar to those reported in children whose K e0 value in the BIS was also greater than in the CSI, although the actual K e0 values of children are larger than those of adults [2,14] . Our mean individual K e0 value for the BIS was 0.36 min -1 , which is comparable to previously reported range (0.22-0.48 min -1 ) [15][16][17][18] .…”

“…The C eff50 and k e0 were expected to decrease with increasing age because age reduces the requirements of sevoflurane and increases the blood-brain equilibration times [14] . However, in our population, the covariate of age did not improve the goodness of fit.…”

The effect of cerebral monitoring on recovery after sevoflurane anesthesia in ambulatory setting in children: A comparison among bispectral index, A-line autoregressive index, and standard practice

“…We also separated the patients into two groups: 3e7 years (n ¼ 126) and 8e12 years (n ¼ 34) similar to Cortínez et al 18 The BIS value was 42.4 AE 12.6 for 3e7 years group and 45.1 AE 14.2 for 8e12 years group ( p ¼ 0.23). There was no significant difference between E'sevo and BIS in different age groups.…”

“…18e20 Previous studies comparing the relationship between E'sevo and BIS in children appeared to be age dependent. 18,19 However, another study found no difference in BIS in children before induction, during maintenance, and on emergence compared with adult values, and suggested that BISguided anesthesia could improve the titration of anesthetics in children. 20 In this study, we examined the relationship between E'sevo and BIS in children.…”

Inhalation and intravenous anesthesia in pediatric patients

“…Diese entspricht nach einer kurzen Latenz der Blutkonzentration [10]. Bei beiden Techniken muss initial mit einer höheren Dosis "angeflutet" werden.…”