A client's serum lidocaine level is 3.0 mcg/mL. What is the nurse's priority intervention?

• A. Increase the lidocaine infusion.
• B. Continue to monitor the client.
• C. Decrease the lidocaine infusion.
• D. Stop the IV drip for 1 hour.

Answer: (B)

Lidocaine given IV as an antiarrhythmic is kept within a therapeutic plasma range, roughly 1.5–5 mcg/mL. A level of 3.0 mcg/mL falls squarely inside this safe window, so the priority is to continue the infusion with careful ongoing monitoring for any signs of toxicity.

Continue to observe vital signs and ECG, and assess for early toxicity symptoms such as perioral numbness, metallic taste, dizziness, tinnitus, or changes in mental status. If the level rises toward or exceeds the toxic range (generally around 5 mcg/mL and higher) or if the patient develops CNS or cardiovascular symptoms, you would adjust therapy by decreasing or stopping the infusion.