1. IV fluids and rate calculations
Jennifer Kean MSN, RN, CCRN

2. IV fluids or medications administered by gravity
Sometimes, you will not have an IV pump available
When gravity is used, infusion sets are used that allow the nurse to count the drops per minute to regulate the flow
IV tubing comes in two sizes:
Macrodrip- delivers 10, 15, or 20 gtts/ml
Microdrip- delivers 60 gtts/ml
The macrodrip set is larger than the microdrip set
In order to calculate the gtts/min, the nurse must know the tubing drop factor

3. When to use which tubing
If large volumes of fluids must be administered, such as 125 ml/hr or more, a macrodrip set is required
When a volume of 50 ml/hr or less is needed, a microdrip set should be used
Usually, the drip chamber of the macrodrip tubing is white, and the drip chamber for the microdrip tubing is blue
And, the microdrip tubing is generally used in the critical care unit for drips (norepinephrine, dopamine, or vasopressin) because they are infused at very slow rates, only about ml/hr
The MD or NP will write the order for the IV type and amount, and also the timeframe over which it must be infused
And, it is the nurse’s responsibility to regulate and maintain the infusion flow rate

4. Remember the formula!
Miss DiLalo’s formula (which I will NEVER forget!)
Ml x gtts Milliliters times drops over minutes
________
Minutes

5. A little bit more about the formula
Convert total hours to minutes
1 hour = 60 minutes
Important!
Total volume to be infused (ml) x drop factor (drops) divided by total amount of time in minutes (minutes)
Example:
500 ml/180 min x 15 gtt/ml x X
500 x 12 x X
X = 41.6, round to 42 gtts/min

6. Another example
Cefuroxime 1 g in 50 ml of NS to infuse over 30 minutes
50 ml/ 30 min x 60 gtts/ml x X
50/30x 2/X
50x2 = 100 gtts/min

7. Infusion via IV pump
Of course, there may be those fine occasions when you have access to an IV pump
Most of the pumps on the market today are “smart” pumps and can be programmed to whatever rate you need
The smart pump will have a library installed- you just enter the first 2 letters of the name of the med, and meds that start with those letters will show on the screen- all you have to do is select the right med and dose
Smart pumps were invented because of problems with too many errors being made
However, you may not get a smart pump, and therefore will have to calculate for ml/hr

8. Another example
Lactated Ringer’s is ordered 1,000 ml to infuse over 12 hours
With this one, you do not have to worry about drops, just solve for ml/h
Formula:
x ml/ h = 1000 ml / 12 h
x = 1000/12
x = 83.3 or 83 ml/hr

9. Try one! Kefzol 1 g in 50 ml D5W to infuse over 30 minutes
So, x ml/ h; xml/h = 50/30 x 60/1
Remember to convert hours to minutes!

10. Answer So.. It’s set at 100 ml/hr What if you don’t have a pump?
Then figure out drops/min; so it would be
100 ml x drop factor/ 30 minutes
100/30 = 33.3, or 33 gtts/min

11. And…
You will need your watch with a second hand when you are setting the tubing drip factor
So, you cannot forget your watch!!!

12. So, it’s really not that hard
Just make sure you know the drop factor of the tubing you are using, the total milliliters to be infused, and over what period of time- or a combination of any of the 3
Don’t forget your watch!
Don’t forget the formula! (Remember Miss DiLalo!!)
And, DON’T STRESS OUT!!! You’ll do great!!!