Evaluation of the accuracy of administration of propofol by a TCI system in children / 中华麻醉学杂志

ABSTRACT

Objective To develop a target-controlled infusion (TCI) system incorporating population pharmacokinetics of propofol for children and evaluate its accuracy. Methods The TCI system was composed of a Samsung Q20 laptop computer, Graseby 3500 infusion pump, Stanpump software (Version 1.0 designed by Shafer et al. Stanford) and pharmacokinetic parameter set for propofol in children reported by Lian et al. Twenty-four ASA Ⅰ children undergoing elective orthopedic or urological surgery under general anesthesia were divided into 2 age groups group A 3-5 yrs ( n = 12) and group B 5-10 yrs (n = 12). Radial artery and internal jugular vein were cannulated. The pediatric patients were sedated with ketamine 4 mg?kg-1 IM (uncooperative patients) or 2 mg? kg-1 Ⅳ( cooperative patients) . Anesthesia was induced with fentanyl 3 ?g?kg-1, propofol by TCI and vecuronium 0.1 mg?kg-1. Target plasma concentration of propofol was set at 3 ?g?ml-1. TCI of propofol was maintained for 60 min. Arterial blood samples were taken at 1, 3, 5, 10, 20, 30, 40, 50 and 60 min after TCI was started and at 2.5, 5, 10, 20 and 30 min after termination of TCI for determination of blood propofol concentration by HPLC. The median performance error ( MDPE) , MDPE without first five minutes ( MDPE1) , median absolute performance error ( MDAPE), wobble and divergence were calculated. Results During the first 40 minutes of TCI there was a remarkable difference between the measured plasma propofol concentration ( Cm) and the target plasma concentration (Cp). The difference was narrowing gradually until the 50 min of TCI. After the termination of TCI the Cm was significantly lower than Cp. The MDPE was 27% in group A and 26% in group B; MDPE1 was 7% (A) and 12% (B) and MDAPE 27% (A) and 26% (B) during TCI. The wobble was 23 % (A) and 24% (B) and the divergence - 0.75%?h-1 (A) and -0.80%?h-1 respectively. Conclusion The bias and divergence of our TCI system for propofol are small and the accuracy is high and a stable plasma concentration of propofol can be maintained in children.