An IV order for 1000 mL D5W to infuse at 125 mL/hour with a drop factor of 10 gtt/mL. How many hours will the IV run?

An IV order for 1000 mL D5W to infuse at 125 mL/hour with a drop factor of 10 gtt/mL. How many hours will the IV run?

• A. 6 hours
• B. 8 hours
• C. 10 hours
• D. 12 hours

Answer: (B)

When the infusion rate is given in mL per hour, the time the IV will run equals the total volume divided by the rate. So, 1000 mL ÷ 125 mL/hour = 8 hours. The drop factor (10 gtt/mL) would be used if you needed the infusion rate in drops per minute, but it isn’t needed to determine how many hours the IV will run. If you did convert to drops, 125 mL/hour × 10 gtt/mL = 1250 gtt/hour, which is about 20–21 gtt per minute, but that doesn’t change the 8-hour run time.

When the infusion rate is given in mL per hour, the time the IV will run equals the total volume divided by the rate.

So, 1000 mL ÷ 125 mL/hour = 8 hours.

The drop factor (10 gtt/mL) would be used if you needed the infusion rate in drops per minute, but it isn’t needed to determine how many hours the IV will run. If you did convert to drops, 125 mL/hour × 10 gtt/mL = 1250 gtt/hour, which is about 20–21 gtt per minute, but that doesn’t change the 8-hour run time.