Local Anesthetic Toxicity

A 38-year-old woman undergoes interscalene brachial plexus block for shoulder arthroscopy at a tertiary care hospital in Delhi. The anesthesiologist uses 30 mL of 0.5% bupivacaine. Within 3 minutes of injection, the patient develops circumoral numbness, tinnitus, and restlessness. Her blood pressure is 145/92 mmHg and heart rate is 98 bpm. What is the most appropriate immediate next step in management?

A 52-year-old man undergoing interscalene block for shoulder surgery receives 20 mL of 0.5% bupivacaine. At 8 minutes, he develops circumoral numbness, tinnitus, and mild tremor. At 12 minutes, he has a brief seizure. Which finding best distinguishes this CNS-predominant toxicity from a case where CV toxicity would be the primary concern?

A 52-year-old man receives 250 mg of 0.5% lidocaine for interscalene brachial plexus block. Thirty minutes later, in the recovery room, he reports dizziness, mild confusion, and tremors. His heart rate is 105 bpm, blood pressure 148/92 mmHg, and oxygen saturation 96% on room air. He is alert and responsive. What is the most appropriate immediate management?

Which of the following local anesthetics has the highest lipophilicity and is most likely to cause systemic toxicity when absorbed rapidly?

A 52-year-old man undergoing interscalene block for shoulder surgery receives 20 mL of 0.75% ropivacaine. After 3 minutes, he develops tinnitus, visual disturbances, and tremors. Which feature would best differentiate early CNS toxicity from systemic toxicity involving the cardiovascular system?