Convulsions after ropivacaine 300 mg for brachial plexus block

A healthy 18-yr-old male (weight 60 kg, height 167 cm), with a history of febrile convulsions in childhood, developed a grand mal convulsion 10 min after the second of two injections of ropivacaine 150 mg, both given incrementally 15 min apart (total 300 mg), for combined axillary/interscalene brachial plexus block. Treatment was with oxygen, lung ventilation, and i.v. midazolam, and the patient made a complete recovery. Arterial plasma ropivacaine concentration 2 min after the onset of convulsions was only 2.13 mg litre(-1), suggesting that this patient was particularly susceptible to local anaesthetic toxicity. Whether sub-clinical EEG changes identified after operation were related to this sensitivity cannot be determined, but review illustrates wide variation in both the dose and the plasma concentration of local anaesthetics associated with systemic toxicity. The UK recommended dose of ropivacaine for brachial plexus block is 225-300 mg according to stature.