07/03/2025
#1. IV Infusion Rate (mL/hr)
Purpose:
Determines how many milliliters per hour (mL/hr) a patient should receive based on the total volume prescribed.
Formula: ( in screenshots)
If time is given in minutes:
Since 1 hour = 60 minutes, convert minutes into hours before applying the formula.
Example Problem
A doctor prescribes 3000 mL of D5W to be infused over 24 hours.
What is the infusion rate in mL/hr?
Solution:
Answer: 125 mL/hr
This means the IV pump should be set to 125 mL/hr to complete the infusion in 24 hours.
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#2. IV Infusion Duration (Time Required for Infusion)
Purpose:
Determines how long an infusion will take based on the prescribed infusion rate.
Formula: ( in screenshots)
Example Problem
A doctor orders 1000 mL of D5W to be infused at a rate of 125 mL/hr.
How long will the infusion take?
Solution:
Answer: 8 hours
This means the IV will run for 8 hours before it is completed.
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#3. IV Drip Rate (Drops per Minute - gtt/min)
Purpose:
When using gravity IV administration (not a pump), the infusion rate is measured in drops per minute (gtt/min) instead of mL/hr.
Formula: ( in screenshot)
• Drop Factor refers to how many drops (gtt) make up 1 mL of fluid.
• It is provided by the IV tubing manufacturer.
• Common drop factors: 10 gtt/mL, 15 gtt/mL, 20 gtt/mL, 60 gtt/mL
Example Problem
A nurse needs to administer 100 mL of Gentamicin sulfate in normal saline over 30 minutes.
The drop factor is 10 gtt/mL.
What is the flow rate in drops per minute (gtt/min)?
Solution:
Answer: 33 gtt/min
Since drops per minute cannot be a decimal, round to the nearest whole number: 33 gtt/min.
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Key Takeaways
1. Use mL/hr for IV pumps – calculated by dividing total volume by time in hours.
2. Use gtt/min for gravity IV sets – calculated using the drop factor.
3. Convert minutes to hours if needed (60 min = 1 hr).
4. Always round appropriately – gtt/min must be a whole number.