A 52-year-old man undergoing interscalene brachial plexus block for rotator cuff repair receives 20 mL of 0.5% bupivacaine. Within 2 minutes of injection, he develops circumoral numbness, tinnitus, and mild restlessness. The anesthesiologist immediately stops the injection and initiates management. Which of the following interventions is NOT indicated in the acute management of this patient's local anesthetic systemic toxicity?