Plasma concentrations of bupivacaine in young infants after continuous epidural infusion

Summary This study reports plasma bupivacaine concentration in seven infants who during major abdominal surgery received lumbar epidural or caudal block anaesthesia. Plasma concentrations (CP) were measured postoperatively after six and twelve h of continuous infusion. Postnatal age ranged from one day to seven months. The local anaesthetic block was performed after induction of anaesthesia. Postoperatively bupivacaine 1.25‐2.5 mg·ml −1 without adrenaline was infused at a rate of 0.5 to 0.83 mg·kg −1 ·h −1 . After six h of infusion the mean value measured was 1.59 μg·ml −1 (range 1.2‐1.94 μg·ml −1 ). After 12 h the mean value measured was 2.06 μg·ml −1 (range 1.53‐2.98 μg·ml −1 ). A marked increase in bupivacaine plasma concentration was seen between six and 12 hours of infusion. Bupivacaine plasma concentration never exceeded 4 μg·ml −1 . Adverse effects that possibly were due to a toxic reaction to bupivacaine were seen in three patients. In conclusion, the dose administered in this study appears to be high and cannot be recommended as safe dosage in this age group.;