Medication Calculation Help

Dratz · Jun 17, 2006

Thanks you two!!..I actually was able to calculate all this using my dose on hand calculation but I think the thing that really had me stumped in the beginning was what the 2000 was. I was stumped as to was it grams? was it mls?....I couldn't find a thing about it in my text. Thanks for the detailed explanation!!.

Daytonite, BSN, RN · Jun 17, 2006

here is some information on the concentration of neostigmine. i found from a couple of sources that 1:2000 was 0.5mg/1ml for neostigmine. from there it was a matter of working backwards to figure out that the ratio 1:2000 meant it equaled 1 gram/ 2000 ml. here are some online sources that show the same thing:

http://www.rxlist.com/cgi/generic3/neostigminems.htm

http://www.nursespdr.com/pdf/bnmn36.pdf

http://www.sicor.com/products/1037.html - this is a supplier's listing of it

sorry if doing all that math to show you dimensional analysis confused you. it's just that it's such a good method to know, especially when you get to working with iv and im meds.

Dratz · Jun 23, 2006

I have been working through a doseage calc workbook over the summer and I am getting so confused with all the formulas I have to memorize for the IV calc's.

It seems there is a formula for every situation. A formula if you don't know the gtts/min, one for if you don't have the time and don't have the volume amount......etc etc ad nauseum.....I am soooo confused.

In the real world of nursing am I going to be expected to calculate some of these really hard calc's in zero time flat? And how on earth does a person memorize all these formulas?

Any tips for me?

Thanks :uhoh3:

DaFreak71 · Jun 23, 2006

I have been working through a doseage calc workbook over the summer and I am getting so confused with all the formulas I have to memorize for the IV calc's.
It seems there is a formula for every situation. A formula if you don't know the gtts/min, one for if you don't have the time and don't have the volume amount......etc etc ad nauseum.....I am soooo confused.
In the real world of nursing am I going to be expected to calculate some of these really hard calc's in zero time flat? And how on earth does a person memorize all these formulas?
Any tips for me?
Thanks

I believe by using only two formulas, you can have all your bases covered.

You need to figure out gtts/min:

total volume x drop rate

____________________

total time x 60 minutes per hour

Just cross cancel to get your gtts/min.

EXAMPLE:

500ml x 16gtts/min

________________

8 hours x 60 minutes per hour =

8,000

_____

480

Answer: 16.666 gtts/min, round to 17gtts/min.

You need to figure out CC's per hour:

In this situation, you will be given information such as how much medicine over a certain number of hours, you have to figure out how much to give PER hour.

Total volume

___________

Total time

Example:

The patient is to receive 750 ml of NS over 16 hours. How many ml per hour?

750 ml

______

16 hours

46.875, rounded to 47 ml per hour.

Hope this helps.

llg, PhD, RN · Jun 23, 2006

I never believed in memorizing formulas -- and never had to. Mathematics is simply logical and I never found a problem I couldn't solve with the basic logic and proportions I learned in junior high.

As a coordinator of orientation programs, I also found that the people who struggled with the math the most are the people who try to solve the problems by memorizing equations. If they focused on understanding the relationships among the quantitiies instead of trying to memorize shrotcuts, they would be able to figure out the answers they needed.

Also, a big problem in trying to do math through memorization (rather than understanding) is that real life situations don't present themselves in the way that always matches what you memorized. Then, you have to rely on your understanding to figure it out. I strongly believe that schools that teach their students to rely on formulas and shortcuts are short-changing their students. They should be teaching their students to understand quantities and relationships and how to "figure things out."

llg

MidnightTang · Jun 23, 2006

llg is right. The easiest way to do clinical calc is just to use proportions. No formulas necessary. You use the same process you use to convert english to metric. Once you've done a few problems it becomes very simple.

Daytonite, BSN, RN · Jun 24, 2006

Learn how to use dimensional analysis to calculate these problems and you won't need to worry about any formulas. All you will need to know is some conversions (seconds to minutes to hours) (milligrams to grams) (milliliters to liters).

indigo girl · Jun 24, 2006

Learn how to use dimensional analysis to calculate these problems and you won't need to worry about any formulas. All you will need to know is some conversions (seconds to minutes to hours) (milligrams to grams) (milliliters to liters).

You are so right!! This works for me every time, and is very logical. I am not a formula type of person. That book, "Dimensional Analysis for Med" by

Anna M. Curren is very helpful to teach how to use this very SIMPLE method.

I would highly recommend it. So, if you hate those formulas, and it sounds like you do, try this out.

llg, PhD, RN · Jun 24, 2006

As much as I usually agree with you Daytonite and Indigo girl ... I do have to advise a little caution with Dimensional Analysis. It is certainly a better approach than trying to memorize formulas, but I have seen lots of new grad orientees who use it struggle with adjusting to the hospital.

Some people teach or learn dimensional anallysis as if it were a magic formula. The students learn to plug the numbers in without understanding the relationships between the items in the situation. To them, the dimensional analysis equation is "just another formula" albeit a more standard one that is generally applicable to most situations. When they encounter a problem that requires multiple steps that are difficult to put in 1 equation, they panic and freeze up.

So I would say ... DA is an OK method to work most math problems, but be sure you don't rely on it exclusively as a "formula" for solving all problems. Be sure to understand the relationships between everything in the problems so that you can figure out situations that require multiple steps and perhaps, multiple dimensional analysis equations.

llg

cand!c3 · Jun 24, 2006

i'm new here:)..and i have the sane problem about calculations, and i read some of your advices and thanks cause you gave tips on how to solve it...

LauraF, RN, ASN, CNA, LPN, RN · Jun 24, 2006

You will need to learn the how to figure out how many drops per minute. How many ml's per minute and such. I did also have to figure out the medicine is ordered now you have to figure out how long of a time to hang it for. Now, with that being said, my instructors gave you time to look it up. If you look in your dosage handbook it tells you that this med needs to be run over xhrs. Most of my instructors wanted to see my calculations so that if I did make an error they could see where and help me understand my error.

Dratz · Jun 26, 2006

Thanks everyone for the great ideas. As for Dimensional analysis, well, we do not use that method here in Canada. I think what will help me is practice, practice and more practice and yes I agree that a person has to actually understand the concept behind the formula itself in order to understand the process. I use ratio/proportion and dose on hand/dose ordered for all my calculations. I will just have to practice more on the advanced IV calc's as that seems to be where I get stuck.

Thanks for all the replies!