Ropivacaine-induced toxicity with overdose suspected after axillary brachial plexus block

Ropivacaine has a high threshold for systemic toxicity. We report and highlight a rare case in which an overdose of ropivacaine was suspected of leading to a generalized convulsion following the injection of this agent for axillary brachial plexus block (ABPB). A 25-year-old woman (height, 153 cm; weight, 48 kg; American Society of Anesthesiologists physical status I) was scheduled for finger surgery with ABPB. The perivascular sheath was identified by fascial clicks. We administered 300 mg (6.25 mg x kg(-1)) ropivacaine, while confirming that no blood flow was observed in the injection line by repeated negative aspiration tests. Ten minutes after the injection, most sensory and motor nerves were blocked effectively. Thirteen minutes after the administration, the patient lost consciousness and convulsed suddenly. No severe symptoms of cardiovascular toxicity occurred. The concentration of ropivacaine in a venous blood sample taken 28 min after the ropivacaine injection was 3.65 microg x ml(-1). She recovered with no sequelae. Limited cases have indicated high efficacy and sufficient safety for the use of 300 mg ropivacaine for ABPB. However, the toxic threshold of ropivacaine remains unclear, and the dose should be calculated in relation to the weight of the patient to prevent severe toxic complications.