The maximum recommended doses of lignocaine are frequently exceeded in
clinical practice as some blocks may need more lignocaine to produce
adequate anaesthesia. We have examined the success rate of brachial pl
exus block, possible toxic symptoms after a dose of lignocaine 900 mg
with adrenaline, and the maximum plasma concentration of lignocaine pr
oduced in 17 adult patients. In all patients, the block was excellent
and no toxic symptoms were encountered. The highest mean lignocaine pl
asma concentration was 2.9 mu g ml(-1) 45 min after the block. We conc
lude that in brachial plexus block, the dose of lignocaine with adrena
line can be as high as 900 mg without fear of toxic symptoms.