Use of lipid emulsion to reverse local anesthetic-induced toxicity

OBJECTIVE: To evaluate the use of lipid emulsion for reversal of local anesthetic-induced toxicity. DATA SOURCES: Literature was accessed through PubMed and OVID (1966-May 2007) using the search terms lipid emulsion and local anesthetic. Reference lists were consulted to identify additional publications. STUDY SELECTION AND DATA EXTRACTION: All articles published in English were evaluated for inclusion. Publications describing the use of lipid emulsion for reversal of local anesthetic in either humans or animals were included. DATA SYNTHESIS: It has been suggested that lipid emulsion (Intralipid) may reverse local anesthetic toxicity by extracting lipophilic local anesthetics from aqueous plasma or tissues or by counteracting local anesthetic inhibition of myocardial fatty acid oxygenation. Studies in rats and dogs have shown that lipid emulsion is effective in resuscitating animals who are asystolic after the administration of intravenous bupivacaine. Three case reports support the use of lipid emulsion to reverse systemic toxicity, including seizures, electrocardiogram abnormalities, and cardiac arrest, resulting from the administration of levobupivacaine, ropivacaine, bupivacaine, or mepivacaine. The regimens used in these cases consisted of bolus doses of 1.2-2 mL/kg followed by continuous infusions of 0.25-0.5 mL/kg/min. All of the patients recovered fully with no neurologic sequelae. CONCLUSIONS: Literature describing animal studies and human case reports suggests that lipid emulsion is effective in the reversal of local anesthetic toxicity. The potential risks of administering the relatively high doses of this agent are uncertain, and the optimal dose has not been established. In light of these uncertainties, it is appropriate to administer lipid emulsion only after advanced cardiac life support has failed and prior to cardiopulmonary bypass.