An IV infusion has a drop factor of 10 gtt/mL. The total volume to infuse is 450 mL over 3 hours. What is the infusion rate in gtt per minute?

An IV infusion has a drop factor of 10 gtt/mL. The total volume to infuse is 450 mL over 3 hours. What is the infusion rate in gtt per minute?

• A. 20 gtt/min
• B. 30 gtt/min
• C. 25 gtt/min
• D. 15 gtt/min

Answer: (C)

Drop factor tells you how many drops make up 1 mL. To find the infusion rate in gtt per minute, multiply the volume to be infused by the drop factor, then divide by the time in minutes. Here, 450 mL over 3 hours equals 180 minutes, and the drop factor is 10 gtt/mL. So the rate is (450 × 10) / 180 = 4500 / 180 = 25 gtt/min. Another way to see it: 450 mL / 180 min = 2.5 mL/min, and 2.5 mL/min × 10 gtt/mL = 25 gtt/min. Therefore, the infusion rate is 25 gtt per minute.

Drop factor tells you how many drops make up 1 mL. To find the infusion rate in gtt per minute, multiply the volume to be infused by the drop factor, then divide by the time in minutes. Here, 450 mL over 3 hours equals 180 minutes, and the drop factor is 10 gtt/mL. So the rate is (450 × 10) / 180 = 4500 / 180 = 25 gtt/min. Another way to see it: 450 mL / 180 min = 2.5 mL/min, and 2.5 mL/min × 10 gtt/mL = 25 gtt/min. Therefore, the infusion rate is 25 gtt per minute.