The relationship between the effect-site concentration of propofol and sedation scale in children: a pharmacodynamic modeling study

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 mu g/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) mu g/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.