Local Anesthetic Systemic Toxicity (LAST)

📧 EM Note Newsletter https://forms.gle/8boToiKDXVE3V8U19 Signup to get free weekly PDF via email. PS: Please join our membership for more perks (members can request for specific PDF file by posting in the EM Note YouTube Membership section). Homepage: EMNote.org ■ 🚩Membership: https://tinyurl.com/joinemnote 🚩ACLS Lecture: https://tinyurl.com/emnoteacls Local Anesthetic Systemic Toxicity (LAST) occurs when excessive plasma concentrations of local anesthetic cause neurologic and cardiovascular complications, representing a life-threatening emergency. Rapid recognition and treatment are essential to prevent potential cardiac arrest or death. Early recognition focuses on neurologic symptoms, which often appear before cardiac collapse. These symptoms include tinnitus, circumoral numbness or metallic taste, sudden altered mental status, confusion, and seizures. Severe cases may progress to loss of consciousness (LOC). Cardiovascular symptoms include bradycardia, hypotension, conduction block, ventricular tachyarrhythmias (VT), and asystole. Immediate management begins with stopping the local anesthetic injection, calling for help, and securing the airway. Practitioners must ensure oxygenation by administering 100% oxygen and avoiding hyperventilation, which prevents alkalosis. The goal is to secure the airway and prevent hypoxia, hypercapnia, and acidosis. The cornerstone of therapy is the immediate initiation of Lipid Emulsion Therapy, which is life-saving. For patients weighing above 70 kg, the protocol involves a 100 mL bolus of 20% lipid emulsion IV over 2–3 minutes, followed by an infusion of 200–250 mL (approximately 0.25 mL/kg/min). For patients below 70 kg, dosages are weight-based: a 1.5 mL/kg bolus followed by a 0.25 mL/kg/min infusion. If the patient remains unstable, the bolus (1.5 mL/kg) can be repeated once or twice, and the infusion rate may be doubled, though the maximum cumulative dose is 12 mL/kg. For seizure management, seizures should be treated promptly using benzodiazepines. Large doses of propofol should be avoided due to the risk of worsening hypotension. Cardiovascular support involves treating hypotension and bradycardia. Small-dose epinephrine (less than 1 mcg/kg) can be used. It is crucial to avoid contraindicated drugs, including vasopressin, beta-blockers, calcium channel blockers (CCBs), and lidocaine. Continuous monitoring is necessary to check for recurrent symptoms caused by the redistribution of the anesthetic.