Systemic Effects of Local Anesthetics

Regarding CNS effects, virtually all local anesthetics stimulate the brain initially, and symptoms such as somnolence, confusion, agitation, excitation, and 

Systemic effects are more likely to occur with long-acting anesthetics if an excessive dose is used, if absorption into the blood stream is accelerated for some reason, or if the drug is accidentally injected into the systemic circulation rather than into extravascular tissues.17 40 Other factors that can predispose a patient to systemic effects include the type of local anesthetic administered, as well as the route and method of administration.3 Therapists and other health care professionals should always be alert for signs of the systemic effects of local anesthetics in patients. Early symptoms of CNS toxicity include ringing/buzzing 

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Covino BG. Toxicity and systemic effects of local anesthetic agents. In Strichartz GR. ed. Local Anesthetics. Handbook of Experimental Pharmacology. Berlin Springer, 1987 81 187-212. 

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