Local anesthetic systemic toxicity: Continuing Professional Development

Abstract

Purpose: Regional anesthesia is enjoying a renaissance due in part to the advent of ultrasound guidance and the development of new techniques such as tissue plane blocks and local infiltration analgesia. The purpose of this Continuing Professional Development module is to provide practitioners with an understanding of the current state of knowledge surrounding local anesthetic systemic toxicity (LAST) in order to help them prevent and manage this complication more effectively.

Principal findings: The causes of LAST are multifactorial, but recognized risks include patient factors, drug doses, pharmacokinetics, and choice of regional anesthetic technique. Local anesthetic systemic toxicity produces a biphasic course of clinical events that generally begin with central nervous system excitation followed by inhibition. At the same time, it causes cardiovascular compromise due to dysrhythmias, myocardial depression, and reduced systemic vascular resistance. Clinical presentation can be highly variable, however, and atypical presentations are not uncommon. Local anesthetic systemic toxicity is prevented by careful choice and dosing of drugs, aspiration before injection, dose fractionation, use of intravascular markers and ultrasound guidance. The management of LAST includes adequate oxygenation and ventilation, seizure termination, maintenance of circulation, and intravenous lipid emulsion therapy.

Conclusions: Local anesthetic systemic toxicity is a potentially lethal condition with protean manifestations, and anesthesiologists must understand its risks, prevention, and safe management.