Fig 1.
Patient flow chart showing information on participant losses and exclusions.
Table 1.
Characteristics of the study population.
Fig 2.
Contour plot showing the density of BIS values and the Sevoflurane Plasma Concentration.
Sevoflurane Plasma Concentration measured in blood samples by gas chromatography during CPB. The plot is based on 159 measurements in the control group (Sevo1.8Vol%) and 223 measurements in the intervention group (SevoBIS) from 48 (20/28) individuals. When the data were analysed using a bivariate method, there was a minimal significant positive correlation between BIS values and the SPC (Pearson’s r 0.172, 95% CI: 0.042 to 0.297, p = 0.010) in the intervention group, SevoBIS. In the bivariate analysis, there was no significant correlation between the BIS values and the SPC (Pearson r -0.119, 95% CI: -0.269 to 0.038, p = 0.136) in the Sevo1.8Vol% group.
Table 2.
Regression coefficients as assessed using the mixed-effects model describing the relationship between BIS values as the response variable and different independent variables during CPB.
Fig 3.
The path model was calculated to estimate the relationships between BIS values as the only endogenous variable and different exogenous variables during CPB. The single-headed arrows represent the regression coefficients; the arrows lead from the explanatory (causal) variable to the outcome variable (effect). The double-headed arrows represent correlations. The figures under the arrowed lines are standardised path coefficients, which must be interpreted according to the product-moment correlation as follows: >.1 = weak effect; >.3 = moderate effect; >.5 = strong effect. The model variables accounted for 43% of the variance of the BIS values. (* = p < 0.01; ** = p < 0.001). EuroSCORE II, European System for Cardiac Operative Risk Evaluation II; HKT, Hematocrit; CPB, Cardiopulmonary bypass.
Table 3.
Causal effects on BIS values and correlations among exogenous variables with standardized path coefficients based on the final path analysis.