I am having trouble with this question, my mind is drawing a blank...

JustBeachyNurse, LPN · May 25, 2014

What are your thoughts so far? How do you think it needs to be set up?

Once you show is what you think, right or wrong, we can guide you.

How I set it up may be different than you have been taught and I may confuse you more

smf0903 · May 25, 2014

"how long will it take for the bag to finish" is your clue for what unit of measure you'll end up with (that should help you set it up accordingly).

:)

Lev, MSN, RN, NP · May 26, 2014

If the drip rate is 10 drops per mL, how many drops is 400 mL?

31 drops infuse per minute. How many minutes will it take for the 400 mL to infuse given the number of drops at the rate of 10 gtt/mL?

D5LR = Dextrose 5% in Lactated Ringers.

Episteme · May 26, 2014

Dear OP: For every nurse's brain, there is probably a unique way it would work through the problem. Here are the series of questions I ask myself when solving the problem.

1. If there are 10 drops for every ml... how many mls are in 31 drops.

2. Solving that gives me the mls/MINUTE. I convert it to mls/hour

3. When I know how many mls/hour I'm infusing... I ask myself how many hours will it take to infuse 400 mls. (Doing a ratio/proportion equation you will be solving for hours.)

But that is only one of a lot of ways to do it.

Nursing2102 · May 26, 2014

Thanks for the advice all..... I am still 110% completely lost though. For some reason I am used to using desired/have formula. I asked 3 nurses at my job to try and do the math, for some reason none of them could figure it out (maybe because they haven't had to do this kind of math for a while???) I asked on of my class mates and she set it up as desired over have.

400mL

31gtts/min

times

1mL

10gtts

She cross multiplied and divided and got the correct answer (129 minutes). I am getting frustrated because I don't understand why she set it up that way. Isn't there usually an X that we are trying to solve for? I'm just so lost aggravated because there is a question like this on my exam next week and I know for a fact I will get it wrong because I cannot for the LIFE of my rationalize the way she set it up.

suzw · May 26, 2014

DO you have to set it up a certain way? DA, cross-multiplying, and all that jazz just confuses me. Seems like too many steps. Like someone said, how many drops in 400mL if there are 10 drops/mL? 4000. How many drops in a minute? 31. So divide 4000/31= 129 and there is your answer.

Or, the way I set it up, before reading the thread, was to figure out how many mL per minute. 3.1, right? How many mL left? 400. Now you already have the right units to divide. Divide 400/ 3.1 and you get 129 again. Don't overthink it. I can't even remember how to do algebra, but I can do these because it all makes sense if you just know what you are looking for.

And stop saying you know you are going to fail, because that's a surefire way to make sure you do. If you can do algebra, you can do this.

Esme12, ASN, BSN, RN · May 26, 2014

The best site for me....DosageHelp.com - Helping Nursing Students Learn Dosage Calculations - Volume/Time - IV mL Rate Questions

nurseprnRN, BSN, RN · May 26, 2014

We see people here all the time that can't read a problem, see which data points are needed and which are distractors/extraneous, and they cram all of it into a big dimensional analysis thing, or some other "sure-fire formula," and come up with a nonsensical answer, and then get flustered and confused. The people who write exams know this, and so they give distractors (wrong answers) that will result when numbers are slotted into formulae without understanding, knowing that some people will pick them because they have no idea to think about the problem. So i prefer to get people to back away, slowly, from the formulae and think about what is going on, what's really being asked, and look at what they know before they start getting flustered about OMGIHAVETOSOLVEAPROBLEM!!!!! :)

You have had several good suggestions on how to think about this, but the best one said to first identify the units used in the answer. Since the question says, "How long...?" that means "time," right? So your final answer ought to be in minutes (or hours and minutes, but you know how to convert a lot of minutes into hours and minutes, I'm sure).

When you think about what you know, you're halfway there. Really.

You know that there are 10gtts in one cc.

You know that your IV is running at 31gtts/minute.

You know that there are 400 cc left.

So. Fool around with those for a minute.

Lessee, now. 400cc is how many drops? 400 x 10 = 4000 drops.

Those 4000 drops are running down the tube at 31/minute. (you know that already)

So.... how many minutes will it take for the 4000 gtts to be used up?

4000/31 = ...