The PHCP prescribes lidocaine at 2 mg/min. The label reads lidocaine 1 gram in 500 mL of 0.9% saline. How many mL per hour will be administered?

The PHCP prescribes lidocaine at 2 mg/min. The label reads lidocaine 1 gram in 500 mL of 0.9% saline. How many mL per hour will be administered?

• A. 60 mL/hr
• B. 30 mL/hr
• C. 120 mL/hr
• D. 15 mL/hr

Answer: (A)

This question tests converting a prescribed rate in mg per minute to an infusion volume per hour using the product’s concentration. First, turn the dose into mg per hour: 2 mg/min × 60 minutes = 120 mg/hour. Then find how much lidocaine is in each milliliter from the label: 1,000 mg in 500 mL equals 2 mg/mL. Now relate the hourly dose to the concentration to get mL per hour: 120 mg/hour ÷ 2 mg/mL = 60 mL/hour. Sanity check: at 60 mL/hour, you deliver 60 × 2 mg/mL = 120 mg/hour, which matches the prescribed rate.

This question tests converting a prescribed rate in mg per minute to an infusion volume per hour using the product’s concentration. First, turn the dose into mg per hour: 2 mg/min × 60 minutes = 120 mg/hour. Then find how much lidocaine is in each milliliter from the label: 1,000 mg in 500 mL equals 2 mg/mL. Now relate the hourly dose to the concentration to get mL per hour: 120 mg/hour ÷ 2 mg/mL = 60 mL/hour. Sanity check: at 60 mL/hour, you deliver 60 × 2 mg/mL = 120 mg/hour, which matches the prescribed rate.