2014 Volume 21 Issue 2 Pages 81-85
Long-acting local anesthetics, such as ropivacaine, bupivacaine, and levobupivacaine, are frequently used for brachial plexus block. Plasma concentration of local anesthetics is highest 15-30 min after injection, and it increases more rapidly after the interscalene approach than after the axillary or subclavicular approach. Adding adrenaline suppresses the increase of plasma concentrations of local anesthetics. An increase of its plasma concentration induces systemic toxicity characterized by a dual-phase response, i.e., excitement and depression in the central nervous and cardiovascular systems, depending on levels of the protein-unbound fraction. Cumulative doses of ropivacaine, bupivacaine, and levobupivacaine for inducing central nervous system toxicity are comparable. It is often manifested by visual, hearing, and speech disturbances with an increase of blood pressure and heart rate. Cardiovascular toxicity characterized by refractory arrhythmia, hypotension, and asystole is often resistant to conventional treatment with adrenaline and antiarrhythmic agents. Because intravenous lipid emulsion is effective for treating local anesthetic-induced systemic toxicity, it should be administered during treatment of such toxicity.
