Study Tips for Dose Calculations

Hello,
I am required to take a dose calculations exam in a few weeks. We have 3 attempts to pass the exam.
I purchased Hegstad & Hayek's "Essential Drug Dose Calculations" study guide. However, I was wondering if any of you had any special tips, calculation/formula short cuts, etc...
Thanks
~Unequaledbeauty~ 

Aug 3, '02Occupation: former RN Joined: Jun '00; Posts: 416; Likes: 192The best tip I know is to use the practice problems, and practice, practice, practice! Good Luck!

Aug 3, '02Occupation: Worrywort Joined: Jul '01; Posts: 1,349; Likes: 16I found that simply reviewing all of my fractions operations and the rules for them was really all I needed. Once I memorized how many gr in a gm and so forth it was just a matter of using the format of working the problems that they will give you.
I didn't use the $35 textbook at all. To understand how the instructor arrived at an answer, I retraced the problem from the answer back.
My instructor had alot of rules for how you formatted your answer such as rounding to the nearest hundreth, and if it's scored you can give 1/2 tab.......etc. There were new rules given at every class.
None of them were in the book, some of them were in the studyguide.
Take notes. 
Aug 3, '02Joined: Jun '01; Posts: 160I found some tips, practice problems and a tutorial on the Student Nurse Forum.
http://kcsun3.tripod.com/
I hope this link works, but if not you can do a web search. Hope this helps you. It sure helped me.
Tonya 
Aug 3, '02Occupation: nursing student Joined: Apr '02; Posts: 44Thank you all for your assistance....
I have been studying the dosage cal study guide & brushing up on my math skills (I'm not a very strong math student ) but I am having a difficult time understanding the mEq (milliequivalent)...
Can you guys help explain that better than the definition in the book. It doesn't really give alot of examples. The books states that, "mEq is one thousandth of a 1 gram equivalent. And that you should pay close attention to the order and label on the drug" That's all it says... nothing more.
For example I have a practice question:
You have a solution labeled Potassium Chloride 10 mEq in 5ml. The doc orders 35 mEq p.o. stat. You will adminster:_____
Maybe I am just slow... but i am having a hard time solving this problem
~Unequaledbeauty~Last edit by Unequaledbeauty on Aug 3, '02 
Aug 4, '02Joined: Apr '02; Posts: 468; Likes: 2010 mEq. 35 Meq.
_____ = _________ = 17.5 ml.
5 ml. X
(5 X 35) divided by 10 = 17.5 ml.
Don't be put off by the weight or volume of what you are trying to solve. The equation will be the same. Say the problem asked you to give 35 mg of a medication that was packaged 10 mg in 5 ml. The problem would be set up the same way.
10 mg. 35 mg.
______ = ______ = 17.5 ml.
5 ml. X
Also make sure your answer makes logical sense. If there are 10 mEq. in 5 ml. and your required dose is close to 30 (30 divided by 10 = 3) then you know that you will need at least 3 times the amount of ml. (3 x 5 ml). Then you would be able to deduct through reasoning that any amount less than 15ml. would be wrong and anything more then 20 ml. would also be wrong.
You can do this!!!!! 
Aug 4, '02Occupation: Worrywort Joined: Jul '01; Posts: 1,349; Likes: 16By Unequaledbeauty
"mEq is one thousandth of a 1 gram equivalent.
so 1/2 gm(0.5 gm) has ________ mEq's?
You can use that comparison of equivalencies to logicaly work out the dosages in gm's or mEq's once you have an order.
Forget that for now.
Your practice problem can be worked out logicaly if you don't trip over the words. The first thing to do is throw out what you don't need.
What you need:
Doctors order written as a fraction 35mEq
______
1
What is on hand written as a fraction 10mEq
______
5mL
You don't need all that other crap.
So.
What do you want to end up with? You won't be measuring mEq's with a syringe will you? You need the answer in mL's right?
A rule: these are ratios so no matter where you put the numbers the total amount contained in that statement 10mEq
_______
5mL
will be the same.... 5mL
_______ It still says that 5mL contains: 10mEq
So if 5mL's contains 10mEq's then how many mL's do you need to draw up for the docs order of 30mEq's?
That's all the order and onhand business is about.......................sifting through the clutter for what you're looking for.
Hope it helps you feel a little better about it.
Peeps 
Aug 4, '02Occupation: Worrywort Joined: Jul '01; Posts: 1,349; Likes: 16Ya' know, this stuff doesn't look much like what I put in my message.
Just write it out on a piece of paper.
I stink at math too, but I got 100/100 on my midterm by just learning fractions operations..really 
Aug 4, '02Occupation: nursing student Joined: Apr '02; Posts: 44Thanks everyone...
I think I got it I am a nervous reck about taking this test... Luckily I have 3 chances to pass it but I would like to pass it the first time around
~Unequaledbeauty~ 
Aug 4, '02Joined: Jul '02; Posts: 128; Likes: 13Not sure if you took your exam already...but I'm also terrible at math. As someone who hates to do math, I LOVE the ratio formula to do problems like these. Here's how I usually do it:
I set it up like this:
amount available = amount ordered
so, this would look like:
10 : 5 = 35 : x (don't really need to write mEq and ml. they
clutter up the problem.)
take the two outside numbers (which are 10 and the x) and
multiply them (equals 10x)
take the two inside numbers (which are 5 and 35) and multiply them (equals 175)
now set it up like this:
10x = 175
Now you want to get the "x" all by itself, so divide each side by 10.
so the problem will look like this:
10x = 175
 
10 10
after dividing each side by 10, the problem will look like this:
x = 17.5 (this is your answer. Just add "ml" next to it and
walla!)
I hope this helps!