You have a 500 mL IV bag to run over 2 hours with a drop factor of 20 gtt/mL. What is the gtt/min?

You have a 500 mL IV bag to run over 2 hours with a drop factor of 20 gtt/mL. What is the gtt/min?

• A. 125 gtt/min
• B. 41.7 gtt/min
• C. 83.3 gtt/min
• D. 166.7 gtt/min

Answer: (C)

The main idea is to convert the total volume over a set time into drops per minute using the drop factor. The formula to use is gtt/min = (volume in mL × drop factor) / time in minutes. Convert the time: 2 hours = 120 minutes. Then calculate: (500 mL × 20 gtt/mL) / 120 min = 10,000 / 120 ≈ 83.3 gtt/min. So the flow rate is 83.3 gtt/min. The other numbers would arise from using different times (e.g., 80, 60, or 240 minutes) but don’t match the 2-hour duration here.

The main idea is to convert the total volume over a set time into drops per minute using the drop factor. The formula to use is gtt/min = (volume in mL × drop factor) / time in minutes.

Convert the time: 2 hours = 120 minutes. Then calculate: (500 mL × 20 gtt/mL) / 120 min = 10,000 / 120 ≈ 83.3 gtt/min.

So the flow rate is 83.3 gtt/min. The other numbers would arise from using different times (e.g., 80, 60, or 240 minutes) but don’t match the 2-hour duration here.