Local Anesthetic Toxicity

Excerpt

Local Anesthetic Systemic Toxicity (LAST) is a rare but potentially life-threatening condition that primarily affects the central nervous system (CNS) and cardiovascular system (CVS), leading to symptoms such as seizures, altered mental status, hypotension, dysrhythmia, acute respiratory failure, and cardiac arrest. With the increasing use of local anesthetics in emergency departments, outpatient settings, and operating rooms, recognizing LAST is crucial, despite the general safety, efficacy, and predictability of these agents .

LAST occurs when the plasma concentration of a local anesthetic exceeds toxic levels, often due to inadvertent intravascular injection, overdose, or rapid systemic absorption from highly vascularized tissues. Early signs may include perioral paresthesia, muscle twitching, dizziness, visual and auditory disturbances, dysarthria, agitation, hallucinations, and altered mental status. Without prompt intervention, these symptoms can quickly escalate to seizures, respiratory depression, and cardiovascular collapse.

Management of LAST requires immediate discontinuation of the anesthetic, supportive care, and, in severe cases, emulsion therapy may be utilized as rescue treatment. Prevention remains essential in clinical practice and involves using the lowest effective dose, aspirating before injection, utilizing ultrasound guidance, and maintaining continuous patient monitoring to minimize the risk of toxicity.