Maternal and foetal plasma concentrations of bupivacaine after epidural block.

Plasma bupivacaine concentrations were measured in 70 mothers and babies (UV) at delivery, after continuous epidural block using bupivacaine 0.5% alone in half the cases and bupivacaine 0.5% with adrenaline (5 μg/ml) in the remainder. Patients received a total dose of 40–500 mg of bupivacaine in 1–10 doses. The mean individual dose was about 47 mg and the mean duration of block 6 hours in both groups. The mean maternal plasma concentration was 0.54±0.05 μg/ml (SE) after bupivacaine alone and 0.36±0.03 μg/ml after bupivacaine with adrenaline. This difference is significant (P