Abstract
Local anesthetic systemic toxicity (LAST) is a rare but potentially life-threatening condition resulting from elevated plasma concentrations of local anesthetics, with serious consequences including central nervous system (CNS) excitation, cardiovascular collapse, and cardiac arrest. Despite advancements in ultrasound-guided techniques and safer anesthetic protocols, LAST remains a significant clinical emergency, often presenting with symptoms such as seizures, agitation, and tinnitus followed by arrhythmias or bradycardia. Timely recognition and intervention are paramount, with intravenous lipid emulsion (ILE; 20% intralipid) now serving as a cornerstone in the treatment of LAST. ILE functions as a "lipid sink," sequestering lipophilic anesthetics from plasma and restoring hemodynamic stability. This report presents a case of a 67-year-old female who developed LAST after a cervical nerve block with ropivacaine during an outpatient surgical procedure. She experienced a brief tonic-clonic seizure and bradycardia shortly after the block, which resolved following the administration of ILE. Upon arrival at the emergency department, the patient was stable with no recurrent symptoms. The clinical presentation, including the temporal relationship between the anesthesia and the onset of symptoms, supported a diagnosis of LAST, which was further corroborated by normal laboratory values and imaging studies that ruled out other potential causes. The patient was observed for 24 hours and discharged without further complications. This case underscores the importance of early detection, prompt intervention with ILE, and extended post-stabilization monitoring in preventing severe outcomes. It also highlights that while ILE therapy remains highly effective, it requires careful adherence to established dosing and monitoring protocols to manage the risk of biphasic toxicity and other complications. The success of this case reinforces the utility of ILE in treating LAST and supports further research into optimizing its use across various toxicological contexts, particularly in older or high-risk populations. As such, this report advocates for a reevaluation of clinical practices surrounding LAST, with an emphasis on patient-specific considerations and prolonged observation to enhance safety and improve outcomes in the management of this challenging condition.