Since the introduction of lidocaine by Lofgren in 1948 it has been widely used for all forms of local, regional and intravenous analgesia. Lidocaine has many advantages over procaine. It is stable, diffuse readily, and produces rapid and profound analgesia. Since the report of toxicreactions to lidocaine by Gordh in 1949. Many authors have reported toxic reactions and fatality due to lidocaine.
This report present 9 cases of toxic reactions to lidocaine which occured in General Hospital, Thomson Road Hospital, and K.K. Hospital in Singapore during 1963~1969, April. Four patients died. Five were suvived.
During this period a total of 77,800 cases of local and regional analgesia(local infiltration block, caudal block, thoraco-lumbar epidural block, brachial plexus block, and pudendal nerve block etc.) was done with lidocaine.
The true incidence of toxic reactioas is not known but 9 cases were conformed and fully documented. Among 77, 8C0 cases, 4 death occured, hence the mortality rate is 19, 450 : 1.
All these 9 cases were given doses of less than 400 mg lidocaine in contrast to previous reports by Gordh (1, 350~3, 000 mg), Deacock, et al. (300~3,000 mg), and Edmcnds-Seal (1,740 mg). Therefore toxic reactions may be influenced by factors other than the total dose of lidocaine. Such as-concentration of lidocaine, site of injection, inadvertent intravenous injection, added adrenaline, patient´s general condition, old age, vascularity of site of injection, pre-existing respiratory or cardiovascular pathology, rate of absorption of drug (tracheobronchial tree etc.), rate of destruction of drug, room temperature, and toxic breakdown product of drug.
Toxic reaction would present when toxic blood lidocaine levels are reached following an overdose, but in these 9 cases the above factors may produce toxic blood levels following a small dose of lidocaine.
Lastly, I emphasize that the concept of toxic reactions to overdose of lidocaine can also follow small doses when the above factors are present.
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