Local anesthetic systemic toxicity (LAST) is a rare but potentially fatal complication of regional anesthesia. LAST frequently begins with neurologic symptoms and can rapidly progress to severe multiorgan dysfunction. In this report, we describe a case of LAST occurring after an ultrasound-guided infraclavicular nerve block.

•Local anesthetic systemic toxicity may initiallypresent with subtle neurologic symptoms before rapidly progressing to multiorgan involvement

•A lack of heme aspiration may not be a reliable marker. Providers may reduce probe pressure to improve aspiration detection

•Consider risk reduction strategies, such as choosing an alternative anesthetic agent or using nerve stimulation

•Epinephrine may be used as an intravascular marker during peripheral nerve blocks, with doses of 10–15 μg demonstrating approximately 80% sensitivity when heart rate increases by ≥10 beats/min or systolic blood pressure rises by ≥15 mmHg.3However, Epinephrine over a threshold dose of 10 mcg/kg impairs lipid resuscitation from bupivacaine overdose

•Early detection and immediate treatment are essential for preventing progression to severe complications