Peripheral Nerve Blocks

A 42-year-old male patient is scheduled for arthroscopic repair of a rotator cuff tear. The surgeon requests a peripheral nerve block for postoperative analgesia. During the interscalene block procedure, the anesthesiologist inadvertently punctures the vertebral artery. The patient suddenly develops severe headache, vertigo, and loss of consciousness within 30 seconds. Which of the following is the most appropriate immediate management?

What is the maximum recommended dose of bupivacaine for a single-shot interscalene block in an adult without epinephrine?

A 58-year-old woman with severe osteoarthritis of the knee is scheduled for total knee arthroplasty under general anesthesia with a femoral nerve block for postoperative pain control. During the block procedure using ultrasound guidance, the needle is advanced medial to the femoral artery and a 'pop' is felt as the needle penetrates the fascia iliaca. After injecting 25 mL of 0.5% bupivacaine, the patient develops sudden onset of severe lower abdominal pain, hypotension (BP 85/50), and tachycardia (HR 118). What is the most likely complication and the immediate next step?

Which of the following local anesthetics has the longest duration of action when used for peripheral nerve blocks?