A 52-year-old man with hypertension and type 2 diabetes undergoes femoral nerve block for total knee replacement at a private hospital in Bangalore. The anesthesiologist injects 40 mL of 0.75% ropivacaine. After 8 minutes, the patient becomes unresponsive, and the monitor shows ventricular fibrillation. ACLS is initiated. What is the most appropriate next step in management?