Plasma bupivacaine concentrations after axillary block in children

Venous plasma concentrations of bupivacaine were measured in children following axillary brachial plexus block with either 2 mg/kg (n = 21) or 3 mg/kg (n = 20) of bupivacaine. Absorption was very rapid with a mean time to peak concentrations of 0.37 hours for both doses. Mean peak plasma concentration was 1.35 mg/l after the 2 mg/kg dose and 1.84 mg/kg after the 3 mg/kg dose. Even after a 30% allowance for anticipated higher arterial concentrations, the plasma levels found in the present study were well below those at which toxicity is considered likely (greater than 4 mg/l).