Systemic toxicity by local anesthetics an adverse reaction that occurs when local anesthetics (AL) reach significant systemic levels, primarily affects the central and cardiovascular nervous system, and while it is an infrequent event, it can be potentially fatal. The main determinant of the toxicity is the plasma concentration of LA, especially the free fraction. The most serious symptoms are seizures and cardiac arrest, which can occur with the administration of any LA. Bupivacaine is the most cardiotoxic of the commonly used LAs, followed in decreasing order by levobupivacaine, ropivacaine and lidocaine.