Correlation between bispectral index and patient state index in children under sevoflurane anesthesia

Background: Because the unanticipated arousal or hemodynamic instability during anesthesia may adversely affect the physical and emotional welfare of children, adequate management of the anesthesia depth is required. We aimed to compare Bispectral Index (BIS) and Patient State Index (PSI) in children during sevoflurane anesthesia and evaluate PSI as depth of anesthesia monitor in children aged 6 months–12 years. Methods: In this prospective observational study, children aged 6 months–12 years old scheduled for elective surgery under sevoflurane anesthesia were enrolled from November 2018 to June 2019. We monitored BIS and PSI at different sevoflurane concentrations. The primary outcome was the correlation between BIS and PSI. The correlation between BIS and PSI at different sevoflurane concentrations (at 1, 1.5, and 2 MACs) and at different age groups (6 months–2 years, 2–7 years, and 8–12 years) was also investigated. Results: Bispectral index and PSI showed a fair correlation (r =.430; 95% confidence interval [CI], 0.297–0.546; p <.001). Two values were fairly correlated at 1, 1.5, and 2 MAC (r =.544; 95% CI, 0.314–0.716; p <.001, r =.509; 95% CI, 0.283–0.699; p <.001, and r =.315; 95% CI, 0.047–0.522; p = 0.007). BIS and PSI values showed a fair correlation in 6 months - 2 year and 8–12 year groups (r =.696; 95% CI, 0.519–0.813; p <.001 and r =.297; 95% CI, −0.017 to 0.543; p <.021), but there was not significant correlation in 2–7 years group (r =.190; 95% CI, −0.015 to 0.374; p =.052). Conclusions: There was a fair correlation between BIS and PSI in children under sevoflurane anesthesia. The use of BIS and PSI as an indicator for anesthesia depth by sevoflurane is not reliable in pediatric patients.