# Figuring out IV drip rates

- 0Nov 26, '04 by RedSox33RNWe have a section on this coming up on our next exam, so I'm studying like a madwoman. Anyway, I wondered if anyone could help with the below problem. I can't figure it out for the life of me:

**Your patient is receiving a unit of blood. The pump is set at 125 and there is 450 ml left to infuse. How long will it take to infuse?**

I get the answer based on 450ml / 125ml = 3.6 hours, but the answer says 3 hours, 36 minutes. Can someone explain how the .6 equals 36 minutes, because I DON'T get it. Unless there is more to the problem than just division, which very well could be.

As a side note, what formula is everyone using for calculating IV flow rates? I know I used a different formula for med dosage calculation than my instructors did, so I could NOT watch when they taught stuff like that in class, or it screwed up my way of doing it (Dimensional Analysis method). I hate that there are so many ways of doing it. One poor woman in our class was in TEARS because she was getting so confused with it. But of course, it is so, so important to know at least ONE of the methods cold. - 20,842 Visits
- 0Nov 26, '04 by NewEnglandRNWhitney,

I wish I had the answer for you. I am drawing a complete blank and know it's something so simple.

I'll be hoping someone comes along soon to answer. - 0Nov 26, '04 by mygirlsmomPretty simple. To get the 36 minutes into decimel form just divide the 36 by 60. The 60 being the number of min. in a hour. That gets you the .6 Hope this helps. Which we are always told to round up or down accordingly.

Cheryl - 0Nov 26, '04 by neneRN3.6 is the same as saying 3 and 6/10ths of an hour. Divide an hour into tenths (60 minutes divided by 10) and you get six. So, if one tenth of an hour is six, then six tenths of an hour (6 x 6) is 36, i.e. thirty six minutes.

Calculating IV flow rates using MAGIC NUMBER method-

Determining which "magic number" you will use depends on your tubing gtt size.

(60 divided by gtt size equals magic number)

For example,

60 gtt tubing; 60 divided by 60 equals ONE.

15 gtt tubing; 60 divided by 15, equals FOUR.

10 gtt tubing; 60 divided by 10 equals SIX.

Okay, so once you know which "magic number" you're using, you then divide your ordered rate (ml/hr) by the magic number to get your gtts/min.

For example,

You have an order for NS at 120cc/hr using 15 gtt tubing. What is your drip rate in gtts/min?

60 divided by 15 equals FOUR (magic number)

120 cc/hr divided by 4 equals 30 gtts/min.

Another example,

Your order is to infuse D5NS at 240ml/hr using 10 gtt tubing. What is your drip rate in gtts/min?

60 divided by 10 equals SIX (magic number)

240ml/hr divided by 6 equals 40 gtts/min - 0Nov 27, '04 by RedSox33RNThank you!!! You've made me a happy studier! LOL

I was just using the magic number method last night also. It does seem a lot easier than the DA or 3-step method. And since there is only 4 numbers to remember, it's pretty easy! - 0Nov 28, '04 by XIGRISJust my 2 cents....

I still wonder why nursing schools gives drip calculation questions using macro, micro drip what so ever. All hospitals have pumps and pumps are more precise in running IV drips the manually adjusting it for 60 gtts/min.

I know we still need to calculate for dosages before adminsitering drugs but questions with macro and micro drips in it hmmm... in the real world you use infusion pumps and you run the IV as ordered....

just wondering....