An IV order calls for 1000 mL of normal saline to infuse over 10 hours with a drop factor of 15 gtt/mL. What is the correct IV flow rate in drops per minute?

An IV order calls for 1000 mL of normal saline to infuse over 10 hours with a drop factor of 15 gtt/mL. What is the correct IV flow rate in drops per minute?

• A. 15 gtt/min
• B. 25 gtt/min
• C. 30 gtt/min
• D. 40 gtt/min

Answer: (B)

The flow rate in drops per minute comes from converting the prescribed volume and time into consistent units and then applying the drop factor. The general rule is: Flow rate (gtt/min) = (Volume in mL × Drop factor in gtt/mL) ÷ (Time in minutes). Here, 1000 mL are to be given over 10 hours. First convert the time to minutes: 10 hours × 60 minutes/hour = 600 minutes. Then compute the rate: (1000 mL × 15 gtt/mL) ÷ 600 minutes = 15000 ÷ 600 = 25 gtt/min. So the infusion should be set to 25 drops per minute. This approach works in any IV calculation: multiply volume by the drop factor to get total drops, then divide by the infusion time in minutes to get drops per minute.

The flow rate in drops per minute comes from converting the prescribed volume and time into consistent units and then applying the drop factor. The general rule is: Flow rate (gtt/min) = (Volume in mL × Drop factor in gtt/mL) ÷ (Time in minutes).

Here, 1000 mL are to be given over 10 hours. First convert the time to minutes: 10 hours × 60 minutes/hour = 600 minutes. Then compute the rate: (1000 mL × 15 gtt/mL) ÷ 600 minutes = 15000 ÷ 600 = 25 gtt/min.

So the infusion should be set to 25 drops per minute. This approach works in any IV calculation: multiply volume by the drop factor to get total drops, then divide by the infusion time in minutes to get drops per minute.