Ultrasound Guidance Reduces the Risk of Local Anesthetic Systemic Toxicity Following Peripheral Nerve Blockade

Background and Objectives: Local anesthetic systemic toxicity (LAST) is a potentially life-threatening complication of local anesthetic administration. In this article, the results of the Australian and New Zealand Registry of Regional Anaesthesia were analyzed to determine if ultrasound-guided peripheral nerve blockade (PNB) was associated with a reduced risk of LAST compared with techniques not utilizing ultrasound technology. Methods: The period of study for this multicenter study involving 20 hospitals was from January 2007 through May 2012. The primary outcome was LAST comprising minor, major, and cardiac arrest (due to toxicity) events determined using standardized definitions. Multivariable logistic regression models and propensity score analyses were used to determine significant event predictors. Results: The study population comprised 20,021 patients who received 25,336 PNBs. There were 22 episodes of LAST, resulting in an incidence of LAST of 0.87 per 1000 PNBs (95% confidence interval, 0.54-1.3 per 1000). Ultrasound guidance was associated with a reduced incidence of local anesthetic toxicity. Site of injection, local anesthetic type, dose per weight, dose, and patient weight were all predictors of LAST. Conclusions: This study provides the strongest evidence, to date, that ultrasound guidance may improve safety because it is associated with a reduced risk of LAST following PNB.