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

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

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 20-50 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

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

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

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

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

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

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!

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

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

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!!!