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The use of propofol infusions in paediatric anaesthesia: a practical guide
C S McFarlan1, B J Anderson, T G Short
1Department of Anaesthesia, Auckland and Starship Hospitals, New Zealand.
Insights
Children need higher propofol infusion rates than adults for anesthesia. This study developed a manual regimen to maintain a steady propofol blood concentration of 3 microg/mL in children aged 3-11 years.
Area of Science:
- Anesthesiology
- Pediatric Pharmacology
- Pharmacokinetics
Background:
- Children require higher propofol infusion rates compared to adults for effective anesthesia.
- Understanding pediatric pharmacokinetic differences is crucial for safe and effective drug administration.
Purpose of the Study:
- To develop a manual infusion regimen for propofol in children aged 3-11 years.
- To achieve and maintain a target steady-state blood concentration of 3 microg/mL.
Main Methods:
- Utilized pharmacokinetic parameter estimates from published pediatric infusion studies.
- Employed pharmacokinetic simulation software to predict propofol blood concentrations.
- Designed a multi-rate infusion regimen with a loading dose.
Main Results:
- A specific loading dose and stepwise infusion rate regimen achieved the target concentration of 3 microg/mL in simulated pediatric patients (3-11 years).
- Predicted infusion rates were higher than those derived from adult data using size models.
- Context-sensitive half-time was longer in children (10.4-19.6 min) compared to adults (6.7-9.5 min).
Conclusions:
- The developed manual infusion regimen effectively targets a propofol concentration of 3 microg/mL in children.
- Pediatric patients exhibit distinct pharmacokinetic profiles, necessitating higher infusion rates and resulting in longer drug elimination times.
- Altered pharmacokinetics in children explain the observed differences in propofol requirements and elimination compared to adults.
Abstract:
Children require higher infusion rates of propofol than adults to maintain clinical anaesthesia. We aimed to produce a manual infusion regimen capable of maintaining a steady-state blood concentration of 3 microg ml(-1) in children aged 3-11 years. Pharmacokinetic parameter estimates were taken from published studies of infusion data in children and used in a pharmacokinetic simulation programme to predict likely propofol blood concentrations during infusions. A variability of 5% was allowed about the target concentration of 3 microg ml(-1). A loading dose of 2.5 mg x kg(-1) followed by an infusion rate of 15 mg x kg(-1) x h(-1) for the first 15 min, 13 mg x kg(-1) x h(-1) from 15 to 30 min, 11 mg x kg(-1) x h(-1) from 30 to 60 min, 10 mg x kg(-1) x h(-1) from 1 to 2 h and 9 mg x kg(-1) x h(-1) from 2 to 4 h resulted in a pseudo-steady state target concentration of 3 microg x ml(-1) in children 3-11 years. We were unable to predict similar rates by applying size models to adult data. The context sensitive half-time in children was longer than in adults, rising from 10.4 min at 1 h to 19.6 min at 4 h compared to adult estimates of 6.7 min and 9.5 min, respectively. Children require higher infusion rates than adults to maintain steady state concentrations of 3 microg x ml(-1) and have longer context sensitive half-times than adults. These differences can be attributed to altered pharmacokinetics in this age group.