School dosage math help

AliNajaCat · Jan 19, 2017

Order: Zosyn 3.375 g in 50 mL NS to be infused over 15 minutes
The answer is: Flow rate: 200 mL/hour

I'm assuming the actual question was something like, "How fast do you set the IV pump?"

It's probably going to be helpful if you know what the actual question is before you start trying to think about how to solve it.

Come on, now, OP, let's hear you think out loud on this. We are trying to help you. Put some effort into it here, let us hear how you think. Once we know that, then it's gonna be useful to show you where you're missing the critical thing, and only THEN should somebody show you how to do the problem. You have to know how to think about it first. You know.... give a man a fish ...

"Mmmmmm, lessee now, I have to give __(amount)__ in 15minutes. So that means ..... "

Ben_Dover · Jan 19, 2017

OP.... heard of Apples with Apples and Oranges to Oranges... AKA Dimensional Analysis.

AliNajaCat · Jan 19, 2017

It is my experience that people with severe math anxiety see the words "dimensional" and "analysis" and their brains just shut down.

It is also my experience over long years of successfully teaching med math to phobics that giving people equations to plug numbers into invariably leads to wrong answers at test time. Why? Because the test question writers often throw in some gratuitous numbers that have nothing to do with the answer, knowing that the equation-memorizers will insist on plugging in every single one of them. The answers from which to choose then include at least two where doing this will result in some kind of answer, some people will get one of those answers doing their screwy equation, and they are wrong.

This is why I stress the ability to read the question and know what it's asking you first, second, and third. Only after you're sure about that should you consider how you would figure it out. It's usually a lot simpler than you think.

Boomer MS, RN · Jan 20, 2017

Pumps are programmed to be set at ml/hour. But this drug needs to go in over 15 minutes. Hint: What proportion of 60 minutes is 15? Try not to over think the problem.

foggnm · Jan 20, 2017

Dosage calculations generally are a ratio, something like this: dose/time=dose/time. So it is 50ml/15min=xml/60min. Which is 60min*50ml/15min=xml.

X=200ml.

Of course it is much easier just to do it in your head and say 15 minutes is 1/4 and hour so I'll multiply the volume x4.

cgw1972 · Jan 20, 2017

We usually run Z 3.375 over 4 hours. Apparently EBP says better therapeutic levels/effectiveness when infused slow.

Calculated that one in your head. 15 into 60 = 4 x 50 mL = 200 mL/hr. Or are you asking how to write it out?? You already have the answer. Just asking.

TriciaJ, RN · Jan 20, 2017

So what happened to the OP? Did she get it figured out?

AliNajaCat · Jan 20, 2017

I have no doubt that she'll be back.

Ben_Dover · Jan 20, 2017

I have no doubt that she'll be back.

For sure! I do hope she gets a tutor!

Pheebz777, BSN, RN · Jan 21, 2017

There are several dosage calculation practice tests online with answers. The only way to get familiar with what equation to use is practice, practice and practice.

NurseLauraM · Jan 27, 2017

Perhaps the names of medications OP is not yet familiar with, as well as the inclusion of grams (which are irrelevant here) are confusing OP. I would replace everything you don't know with cheeseburgers.

I ate 50, 3.375g cheeseburgers in 15 minutes. If I ate cheeseburgers at this pace for an hour, how many would I eat?

200 cheeseburgers. Why? Because there are four 15 minute cheeseburger-eating-intervals in an hour, each worth 50 cheeseburgers. 50 cheeseburgers x 4 = 200 cheeseburgers.

Does it matter that each cheeseburger was 3.375 grams? Nope! At least not for this math problem.

Yum.

SouthernBelle85 · Jan 28, 2017

So pumps are usually set at ml/hr

Yet this med needs to be infused in 15 minutes.

So there are 60 minutes in a hour. 60 divided by 15 equals 4.

50 times 4 equals 200 ml/hr Sometimes I do equations though sometimes I am better just talking it out like that.....I do pretty well on dosage calculations, so I guess it works for me.

Maybe the 3.375 g was throwing you off?