Introduction to IV Flow Rates and Infusion Time
Vocabulary
gtt – drop
microdrip – 60 gtt/mL
1. Dimensional Analysis Review
Understanding how to calculate IV flow rates and infusion time is an essential skill for nurses. To accomplish this task, dimensional analysis (unit matching) is the preferred method. The rate and quantity of intravenous fluid given depend on the client’s medical condition, body size, and age. Regulation ensures the correct amount of fluid drips from a bag down the IV into the vein at the correct rate. Complications can result from receiving too much too quickly, or not enough too slowly. Infusion time is the length of time it takes for the infusion to complete.
Rule 1. Set up the problem. What units will your answer have?
[latex]\frac{unit}{1} -or- \frac{unit}{unit}[/latex]
Rule 2. Work the problem until the unit(s) on one side match the units on the other.
Rule 3. Do your units MATCH?
Rule 4. Solve by multiplying all the top numbers and write the answer in the numerator and then multiply all the bottom numbers and write the answer in the denominator.
[latex]\dfrac{numerator}{denominator}[/latex] = Dive the top by the bottom
Rule 5. Write the number to four (4) decimals and then round and write your units appropriately.
2. Conversions Steps
As always, read the question carefully and identify relevant information. Start with the end in mind when setting up your dimensional analysis and round your final answers for gtt/min and mL/hr to the nearest whole number.
IV Flow Rate & Infusion Time Conversion Examples
1. A physician orders Ofirmev 1,000 mg in 500 mL of normal saline IV
over 45 minutes as a one-time dose. How many milliliters per hour would
the nurse program the IV infusion device?
Solve:
mL → [latex]\frac{500mL}{0.75 hrs}[/latex] = [latex]667mL/hr[/latex]
2. A patient has Acyclovir 480 mg in 150 mL of NS ordered to infuse over 120 minutes. The IV tubing has a 20 drop per milliliter factor. How many drops per minute would the Acyclovir be infused?
Solve:
gtt/min → [latex]\frac{150mL}{120min}[/latex] = [latex]25 gtt/min[/latex]
3. An IV of 1500 mL NS to infuse at 60 mL/hr. Determine the infusion time. If the IV was started at 1400, when would the IV infusion be completed?
Solve:
hr → [latex]\frac{1hr}{60mL}[/latex] x [latex]1500mL[/latex] = [latex]25 hours[/latex]
1400 + 25 hours = 1500
2:00 PM + 25 hours = 3:00 PM the following day
IV Flow Rates and Infusion Time Video Tutorial
drop
60 gtt/mL
