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Free and total bupivacaine plasma concentrations after continuous epidural anaesthesia in infants and children
G Luz1, C Wieser, P Innerhofer
1Department of Anaesthesia, University Hospital, Innsbruck, Austria.
Insights
Free bupivacaine levels, not just total, are crucial for assessing toxicity in infants receiving epidural anesthesia. Lowering bupivacaine doses in young children is recommended to prevent adverse reactions.
Area of Science:
- Pharmacology
- Anesthesiology
- Pediatrics
Background:
- Bupivacaine is commonly used for epidural anesthesia in infants and children.
- Assessing bupivacaine toxicity is critical, especially in vulnerable pediatric populations.
Purpose of the Study:
- To measure free and total venous bupivacaine plasma concentrations in infants and children undergoing epidural anesthesia.
- To investigate the relationship between bupivacaine concentrations and adverse reactions in different age groups.
Main Methods:
- Measured free and total bupivacaine plasma concentrations in 14 infants and children (6 days to 9 years).
- Administered an initial bolus followed by a continuous epidural infusion of bupivacaine.
- Analyzed plasma concentrations in relation to patient age and observed adverse events.
Main Results:
- Total bupivacaine concentrations remained within acceptable limits (< 1.5 µg/mL).
- Four of seven infants experienced adverse reactions.
- Free bupivacaine plasma concentrations were significantly higher in infants compared to older children (P < 0.05).
Conclusions:
- Total bupivacaine concentration alone may underestimate toxicity risk in pediatric patients.
- Recommended bupivacaine doses for continuous epidural anesthesia in young infants should be reduced.
- Close patient observation for adverse reactions is essential in this population.
Abstract:
We measured free and total venous bupivacaine plasma concentrations in fourteen infants and children aged 6 days (2800 g) to 9 years (27 kg) undergoing epidural anaesthesia. An initial bolus of 0.5 ml.kg-1 bupivacaine 0.25% was followed by a continuous infusion administered one h after bolus over a period of seven h (first hour 0.25 ml.kg-1.h-1 0.25%; then reduced to 0.125%). Although total bupivacaine plasma concentrations were within acceptable limits (< 1.5 micrograms.ml-1), four of the seven infants showed adverse reactions. Maximum plasma concentrations of free bupivacaine were significantly higher in infants (P < 0.05) than in older children. We conclude that toxicity may be underestimated when only measuring total bupivacaine concentrations. In young infants the bupivacaine dose administered for continuous epidural anaesthesia should be further lowered below recommended concentrations and the patients closely observed for possible adverse reactions.