Signs of lidocaine toxicity and occurrence of clinical
adverse events
All patients’ median and IQR plasma lidocaine levels (ng/ml) do not
exceed toxic levels at each measured time point of 5, 10, 15 and 20
minutes. However outlying plasma lidocaine levels exceeding 5000ng/ml do
exist at every time point. Nevertheless there were no incidences of
clinical adverse events or symptoms of local anaesthetic toxicity. This
suggests toxic levels may differ between intravenous and mucosal
administration of local anaesthetic agents. Our median time to peak
plasma lidocaine concentration was 10 minutes as demonstrated in Table
1.
Four patients in the study exceeded lidocaine plasma levels of
5000ng/ml. Summary of demographics, baseline and descriptive data for
these patients are in Table 2. There was no relationship between
exceeding toxic lidocaine levels and age, weight or surgical procedure.
However, a sample size of 4 in one group does not provide enough power
to detect a difference.