Background: Peripheral Nerve Blocks are used widely and have improved patient safety and satisfaction while diminishing complications related to general anesthesia. However, Local Anesthetic Systemic Toxicity remains an adverse effect with probable detrimental consequences. We report the management of a case of LAST after Combined Psoas Compartment and Sciatic Nerve Block for a femoral neck fracture that allowed stabilization of the patient and conduct of operation.

Case Report: A 96 year old female presented to the orthopedic department after suffering a right femoral neck fracture. She was classified ASA III physical status as her medical history included chronic atrial fibrillation, hypertension and dementia. She reported a stroke with neurological deficit one month ago. Standard monitoring plus an arterial line were placed. Using a nerve stimulator a total of 25ml Lidocaine 1% and 25ml Ropivacaine 0,5% were injected with negative aspiration test for psoas compartment and sciatic block after proper muscle response. 5 minutes after completion, upper body convulsions, altered mental status and hemodynamic instability developed. Prompt recognition of LAST guided IV infusion of 1,5ml/kg 20% lipid emulsion over 1 minute followed by continuous infusion of 0.25ml/kg/min and midazolam 5mg were administered while intubation was commenced. Titrated vasopressor support allowed normalization of hemodynamic parameters and the surgery was performed successfully. The patient was transferred intubated in the ICU and discharged the following day to orthopedic department.

Discussion: Elderly patients with major comorbidities pose a challenge for anesthetists. Peripheral nerve blocks can offer hemodynamic stability when other anesthetic options may be considered high risk. However, LAST can be a devastating event and patient characteristics can amplify the risk of occurence. Its diverse clinical presentation and the probability of late onset toxicity demands thorough monitoring. Emergency equipment and drugs including lipid emulsion must be readily available. 

Learning points: LAST although rare is a major and potentially fatal event. Thus, proper organization of departments which commence PNBs must permit prompt management of this complication. Immediate recognition and management can lead to reversal of adverse symptoms and stabilization to proceed with the operation. 

11 / Local Anesthetic Systemic Toxicity in an elderly patient for urgent surgery