Recent advances in local anaesthesia.

In general, the cardiovascular system is more resistant to the toxic actions of local anaesthetics than is the central nervous system. However, if sufficient doses and blood levels of local anaesthetics are achieved, signs of profound cardiovascular depression may be observed. Differences exist between local anaesthetics in terms of their relative potential for cardiotoxicity. The CC/CNS ratio for bupivacaine and etiodcaine is less than for lidocaine. In addition, bupivacaine may precipitate ventricular arrhythmias and ventricular fibrillation. Local tissue toxicity can occur following the administration of local anaesthetics. In general, neural tissue appears to be relatively resistant to the irritant effects of local anaesthetic drugs. However, large dosages of chloroprocaine solutions administered intrathecally have been associated with prolonged sensory-motor deficits in a few patients due probably to the low pH and presence of sodium bisulfite in the chloroprocaine solutions. In general, the incidence of toxic reactions to local anaesthetic agents is extremely low. However, as with any class of pharmacological agents, local anaesthetics may cause severe toxic reactions, due usually to the improper use of these drugs.