A 48-year-old male with a history of liver cirrhosis is undergoing a minor surgical procedure for excision of a skin lesion. The patient was injected with 30 mL of 2% lidocaine (600 mg) without epinephrine for local anesthesia. Shortly after the injection, he reports a metallic taste in his mouth, dizziness, and ringing in his ears. Within minutes, he develops perioral numbness and confusion, followed by generalized muscle twitching. The patient becomes drowsy but responsive, with involuntary muscle twitching. Blood pressure was 140/90 mmHg, heart rate 98 bpm, and oxygen saturation was 96% on room air. His weight was 60 kg. Within moments, he becomes unresponsive and experiences a tonic-clonic seizure lasting approximately 30 seconds. After the cessation of seizure, his blood pressure drops to 80/50 mmHg, and his heart rate falls to 40 bpm, with signs of cardiovascular collapse. What is the most effective antidote to treat cardiovascular collapse in this patient?
