An IV order for 500 mL of D5W to infuse over 8 hours with a drop factor of 20 gtt/mL. What is the flow rate in drops per minute?

An IV order for 500 mL of D5W to infuse over 8 hours with a drop factor of 20 gtt/mL. What is the flow rate in drops per minute?

• A. 15 gtt/min
• B. 21 gtt/min
• C. 25 gtt/min
• D. 30 gtt/min

Answer: (B)

Calculating IV flow rate uses volume, time, and drop factor. The drop factor tells how many drops make up 1 mL, so you multiply the volume by the drop factor to get the total drops, then divide by the infusion time in minutes. Here, 500 mL to be infused over 8 hours with a drop factor of 20 gtt/mL. Convert time to minutes: 8 hours × 60 minutes/hour = 480 minutes. Multiply volume by drop factor: 500 mL × 20 gtt/mL = 10,000 drops. Now divide by time: 10,000 drops ÷ 480 minutes ≈ 20.83 drops per minute. Rounding to the nearest whole drop gives 21 gtt/min. So the flow rate is about 21 drops per minute. The exact calculation yields 20.83, which rounds to 21, matching the chosen result.

Calculating IV flow rate uses volume, time, and drop factor. The drop factor tells how many drops make up 1 mL, so you multiply the volume by the drop factor to get the total drops, then divide by the infusion time in minutes.

Here, 500 mL to be infused over 8 hours with a drop factor of 20 gtt/mL. Convert time to minutes: 8 hours × 60 minutes/hour = 480 minutes. Multiply volume by drop factor: 500 mL × 20 gtt/mL = 10,000 drops. Now divide by time: 10,000 drops ÷ 480 minutes ≈ 20.83 drops per minute. Rounding to the nearest whole drop gives 21 gtt/min.

So the flow rate is about 21 drops per minute. The exact calculation yields 20.83, which rounds to 21, matching the chosen result.