Blood levels of bupivacaine after single dose, supplementary dose and during continuous infusion in axillary plexus block.

The material consisted of 25 patients undergoing orthopaedic or plastic surgery of the upper extremity, including seven cases of replantation surgery. The total doses of bupivacaine, 150-267 mg as a single dose, 280-440 mg as a supplementary dose and 247-629 mg as a continuous infusion, resulted in maximum venous concentrations of 0.68-3.33 micrograms/ml, 1.21-2.44 micrograms/ml and 0.51-1.89 micrograms/ml, respectively. These usually occurred 30-60 min after the injection of bupivacaine and always following the second injection when a supplementary dose was needed. The highest individual value noted occurred 15 min after single injection, possibly as a result of an exceptionally rapid absorption. Despite the high doses and the rather high venous peak concentration of bupivacaine in some of the patients, no toxic side-effects were observed during the block or during the recovery period.