Summary: | Abstract Background Continuous infusion of propofol has been used to achieve sedation in children. However, the relationship between the effect-site concentration (C e ) of propofol and sedation scale has not been previously examined. The objective of this study was to investigate the relationship between the C e of propofol and the University of Michigan Sedation Scale (UMSS) score in children with population pharmacodynamic modeling. Methods A total of 30 patients (aged 3 to 6 years) who underwent surgery under general anesthesia with propofol and remifentanil lasting more than 1 h were enrolled in this study. Sedation levels were evaluated using the UMSS score every 20 s by a 1 μg/mL stepwise increase in the C e of propofol during the induction of anesthesia. The pharmacodynamic relationship between the C e of propofol and UMSS score was analyzed by logistic regression with nonlinear mixed-effect modeling. Results The estimated C e50 (95% confidence interval) of propofol to yield UMSS scores equal to or greater than n were 1.84 (1.54–2.14), 2.64 (2.20–3.08), 3.98 (3.66–4.30), and 4.78 (4.53–5.03) μg/mL for n = 1, 2, 3, and 4, respectively. The slope steepness for the relationship of the C e versus sedative response to propofol (95% confidence interval) was 5.76 (4.00–7.52). Conclusions We quantified the pharmacodynamic relationship between the C e of propofol and UMSS score, and this finding may be helpful to predict the sedation score at the target C e of propofol in children. Trial registration http://www.clinicaltrials.gov (No.: NCT03195686 , Date of registration: 22/06/2017).
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