Best method for figuring dosage calculations!!!!

BacktotheBeach, ADN, BSN, RN · Aug 4, 2010

I'm no veteran, just starting NS this fall, but I love this website. They will email you a dosage question of the day. I did take a class called 'dosage calculations' at my school, and I used the ratio proportion method and really liked it.

http://www.dosagehelp.com/

TheSquire, DNP, APRN, NP · Aug 4, 2010

Dust off your general chemistry textbook and do dimensional analysis. You'll be able to convert anything to anything else and you won't have to remember any cutesy formulas or "methods".

knittingmonster · Aug 4, 2010

I'm all about the dimensional analysis. I can't remember formulas to save my life and I also can never figure out what number goes on top and bottom. With dim. analysis, I just plug numbers in so that the units cancel out. It hasn't failed me yet!

Nurse Connie · Aug 4, 2010

I'm most comfortable with ratios. I've always done well in algebra so this is the easiest for me.

anonymousstudent · Aug 4, 2010

I'm most comfortable with ratios. I've always done well in algebra so this is the easiest for me.

I use ratios too. It *almost* always works. With ratios I find that I can do calculations very quickly in my head. I hate standing there with a calculator. :uhoh3:

locolorenzo22, BSN, RN · Aug 5, 2010

i often find that taking (dose desired)/(dose on hand) X units available works the best.

10 mg of Lasix if it comes 30mg per 2 mls. 10mg/30mg X 2 Mls= .6666666666 Mls...round to the tenth. 0.7 mls.

Schweet · Aug 5, 2010

I found dimensional analysis to be the easiest. Just put what you want (i.e. milliliters) on the top left side of the equation and plug in everything else according to their label in order to cancel them out. Multiply the top, divide it by the bottom. Then you match up the labels, cancel them out in pairs and wallah! You have your answer.

That may not make sense but once you learn how to do it, it's an easy method of doing dosage calcs. Look for books at your school library or on half.com that are dimensional analysis for nurses.

Also, your school may offer a dosage calc. class but it's too late for that now. Congrats on starting nursing in the fall!

Intern67 · Aug 5, 2010

Hi all!!
I've been working on dosage calcs off and on this summer so I can be prepared for this fall when I start Nursing school:lol2: I'm curious to know from you veterns out there which method is the best. Right now I am finding the formula method the best!! Tips, hints or ideas are GLADLY welcomed!!!
Thank you!!

The formula method works fine for very simple and straightforward problems.

However, once you get into flow rates, surface area/body weight, stuff like that, there will not be an easy to use formula handy. Learn dimensional analysis and it will be your friend for a long time.

llg, PhD, RN · Aug 5, 2010

As someone who has taught new grads in hospital orientations, I find that anyone who uses a "single method" (whether it be specific formulas they have memorized or dimensional analysis) struggles more with real-life situations.

Real-life situations don't come at you in the same neat, tidy way that test questions do. They can be messy and disorganized. Pieces of information may be missing ... or you may have to solve a series of problems before you get the numbers you need to calculate the final answer. In my experience, the people who do well with real-life situations are those that approach the problems conceptually, understand the relationships between quantities and measurements, and can "see their path" through a series of calculations (usually proportions) that lead them towards their final answer.

In short -- gimmicks don't work as well as truly understanding the principles of mathematics (quantities and relationships) that underlie the problem. People with a grasp of those underlying principles can work their way through any problem. People without that grasp can use their gimmicks for the simple, straightforward problems -- but are often stumped by really complex situations that match the format of their usual method.

So I guess the answer is: Any one of the standard ways will work for the types of easy, straightforward problems you are likely to see on a school quiz. But for the messy, real-life situations -- the best nurses use multiple methods based on a solid understanding of the underlying principles.

Bob_N_VA · Aug 5, 2010

I would think the school would teach you Dimensional Analysis in the first term. Other than that, you can practice math and algebra if you think you need some refreshing. When you get into things like flow rates, it really has to be set up correctly so there isnt a standard method that will work across the board.

Multicollinearity, BSN, RN · Aug 5, 2010

In nursing school I never used any formula that I was aware of. I'd just look at the question and start the math with a conceptual understanding of what I need to do and where I needed to go with the numbers. I never missed a single math/dose question in nursing school. Some of my classmates who memorized all of these formulas without understanding the underlying concepts missed questions now and then due to making mistakes and not understanding what they were doing with the numbers in the formulas.