(683) Management of Local Anesthetic Systemic Toxicity: Successful Outcome With Lipid Emulsion Therapy

Introduction: Local anesthetic systemic toxicity (LAST) is a rare but serious complication that occurs when local anesthetics, enter the bloodstream in sufficient quantities to affect other organs and systems beyond the intended site of action. The incidence is estimated at 0.03%, translating to 0.27 occurrences per 1,000 peripheral nerve blocks. Herein we highlight a rare incidence of LAST attributed to intra-articular infusion, a less common route compared to intravenous or intramuscular administration.

Description: A 72-year-old female status post-total knee replacement on a ropivacaine pump presented with encephalopathy, respiratory depression, and hypotension. Clinical examination revealed right-sided weakness and downward gaze deviation. Imaging and laboratory investigations were notable for elevated liver enzymes, creatinine, and troponins. Prompt recognition of LAST led to cessation of the ropivacaine infusion and initiation of supportive care including intubation for airway protection, epinephrine for hemodynamic support, and lipid emulsion therapy. The patient clinically improved with resolution of neurological deficits and eventual transition to high-flow nasal cannula (HFNC).

Discussion: Our case stands out due to the administration of ropivacaine via an intra-articular pump, rather than the conventional routes of IV or IM administration. This unique scenario broadens the scope of LAST considerations and emphasizes the necessity for broad differentials. Prompt recognition lead to cessation of the ropivacaine infusion and initiation of supportive care. However, the treatment that led to rapid improvement was lipid emulsion therapy. Lipid emulsion therapy acts by creating a lipid sink, effectively sequestering the circulating ropivacaine away from sensitive tissues and thereby mitigating its toxic effects.

Following lipid emulsion therapy, our patient demonstrated remarkable improvement. Neurological deficits resolved, allowing for successful extubation and transition to HFNC. Continued awareness of preventive strategies among healthcare providers is essential in ensuring the safe administration of regional anesthesia and minimizing the risk of local anesthetic systemic toxicity.