A nurse is reviewing a prescription for potassium chloride 20 mEq to be infused over 2 hours. The bag label shows 20 mEq in 250 mL. What rate should the infusion pump be set to (mL/hour)?

• A. 125 mL/hour
• B. 100 mL/hour
• C. 150 mL/hour
• D. 80 mL/hour

Answer: (A)

Flow rate is the volume of solution delivered per hour. The bag contains 250 mL to deliver 20 mEq, and the order is to infuse that amount over 2 hours. So the pump rate is 250 mL divided by 2 hours, which equals 125 mL per hour. You can also think in terms of concentration: 20 mEq in 250 mL is 0.08 mEq per mL. To deliver 20 mEq over 2 hours, that’s 10 mEq per hour; at 0.08 mEq/mL, you need 10 ÷ 0.08 = 125 mL per hour. Set the pump to 125 mL/hour to deliver the prescribed dose within the specified time.