Author: Sunder, Rani A. et al.
Anesthesiology ():10.1097/ALN.0000000000005775, September 29, 2025. doi:10.1097/ALN.0000000000005775
This study evaluated the pharmacokinetics of ropivacaine and its metabolite PPX in children receiving lumbar plexus blocks. Twenty patients aged 4–18 years underwent hip or femur surgery with a 2 mg/kg bolus of 0.2% ropivacaine followed by a 0.4 mg/kg/h infusion. Blood sampling was performed over 26 hours.
There was marked variability in drug handling, with a 5-fold range in unbound ropivacaine concentrations and a 10-fold range in PPX levels. Modeling showed that standard continuous infusions plus repeated boluses approached toxic thresholds, especially due to delayed accumulation of PPX. Switching to intermittent boluses every 6 hours provided safer plasma concentrations while maintaining analgesic coverage.
The authors suggest that while an infusion plus bolus strategy is acceptable in the first 24 hours, bolus-only dosing should be considered thereafter to reduce toxicity risk in pediatric lumbar plexus blocks.
What You Should Know
Continuous ropivacaine infusions in children can lead to toxic metabolite buildup over time. After 24 hours, replacing infusions with timed bolus dosing may improve safety while still providing effective analgesia.
Thank you Anesthesiology for publishing this article.