400 mL NS to infuse over 4 hours with a drop factor of 15 gtt/mL. What is the flow rate in drops per minute?

400 mL NS to infuse over 4 hours with a drop factor of 15 gtt/mL. What is the flow rate in drops per minute?

• A. 20 gtt/min
• B. 25 gtt/min
• C. 30 gtt/min
• D. 35 gtt/min

Answer: (B)

The key idea is to compute the IV flow rate in drops per minute using volume, time, and the drop factor. The drop factor (gtt/mL) tells how many drops make up 1 mL, so first find the total drops to be administered: 400 mL × 15 gtt/mL = 6000 drops. Next, convert the infusion time to minutes: 4 hours × 60 minutes/hour = 240 minutes. Finally, divide total drops by total minutes to get the flow rate: 6000 drops ÷ 240 minutes = 25 drops per minute. So, the flow rate is 25 gtt/min.

The key idea is to compute the IV flow rate in drops per minute using volume, time, and the drop factor. The drop factor (gtt/mL) tells how many drops make up 1 mL, so first find the total drops to be administered: 400 mL × 15 gtt/mL = 6000 drops. Next, convert the infusion time to minutes: 4 hours × 60 minutes/hour = 240 minutes. Finally, divide total drops by total minutes to get the flow rate: 6000 drops ÷ 240 minutes = 25 drops per minute. So, the flow rate is 25 gtt/min.