The Nursing Math Thread

How Do i solve this problem?

You are to give Aqueous Penicillin 600,000 Units. Available Aqueous Penicillin (powder) 1,000,000 Units per vial. Add 3.6 mL sterile water. Prepared solution will then be 250,000 Units per mL.

What will you give to your client?_____

250,000units: 1mL :: 600,000 units : XmL

250,000 X = 600,000

X= 2.4mL

250,000units: 1mL :: 600,000 units : XmL

250,000 X = 600,000

X= 2.4mL

Thanks. that is a simple problem but I never knew that 250,000 units = 1 ml. I don't remember it being taught to me.

the label gave you the final solution of 250,000 units per 1ml, each label will have a different final solution ie 100mg per 1ml, 100,000 units per 2ml, does that make sense, in other words read the label for the final solution, not that 250,000 units will always equal 1ml.

Thanks. that is a simple problem but I never knew that 250,000 units = 1 ml. I don't remember it being taught to me.

I was going to say what mb said...always dissect your problem and use the useful info and toss out the rest. If the problem is on paper cross out the extraneous stuff (or the stuff they put in to confuse you) and then you will see the "meat" of the problem. I used Ratio and Proportion on that one, I do that on all problems except IV drip rates; those I use Dimensional Analysis on. Good luck and feel free to ask for more help! I just graduated in May and I struggled with the math until the last semester of school, then it just seemed to "click".

i forgot/cant find anywhere how to convert 'units to ml'!!

the question=

physician prescribes 2 U of prbc to infuse over 1 hour each, drip factor is 10 gtt/ml, find drops per minute

i just need to know the conversion of UNITS TO ML, please and thanks

A member pm'd me the following question highlighted below. We created this thread for you guys to talk about math, solve math problems, and post math websites that you have found helpful.

I was wondering, is there a sticky or a special site that can be coordinated for "math sufferers". Perhaps, beginning calculations or shall i say the basics..simple to complex...step by step on how to calculate. I'm a visual learner, numbers and I don't work well. I am trying, but I've got a block!

This will come in handy once someone puts something on here. I've already had Algebra, but have to take it again. Bummer!!!1:mad:

henke's med math helps me alot!

Does anyone know what the easiest way to solve this problem is? Thank you!

Your client ate 60% of a 16 oz steak. The steak is 45% protein. How many grams of protein did your client eat?

60% of 10oz =9.6oz

45% of 9.6oz= 4.32oz

oz to grams conversion = x28

4.32oz= 120.96grams

how do i solve this problem?

you are to give aqueous penicillin 600,000 units. available aqueous penicillin (powder) 1,000,000 units per vial. add 3.6 ml sterile water. prepared solution will then be 250,000 units per ml.

what will you give to your client?_____

more words than you needed, lol. i have done these same calculations for chemistry and chemical engineering for years. in these dosage questions for nursing, they always throw in superfluous information that you don't need. in this case, they told you how they made the final solution, the concentration of which was 250,000 units of penicillin per ml of liquid solution, and you really didn't need to know that to solve the problem. these dosage calculations are kind of "follow the money" problems, lol. you need to get a certain amount of penicillin into the patient, and the water of the solution is the vehicle that it rides in on.

so, what you key off of, in this case, is the amount of penicillin you want to dose the patient with, which they told you is 600,000 total units of (essentially dry) penicillin. and it's riding in water, as a solution. so, you use dimensional analysis (or factor label, as it's also called), as someone already showed here. you want 600,000 units of penicillin itself in that patient, but it's in a solution with water, and there are 250,000 units of p-cillin in one ml of the solution. so, you know that you need more that one ml of solution. to figure out how many ml to inject into patient, it's 600,000 units that you want, divided by 250,000 units per ml of solution = 600,000/250,000x 1ml = 2.4 ml of solution that you need to administer.

in all of these problems, it's "follow the money", the drug. you want a certain quantity of it to go into the patient, and you inject / pump / pill whatever it volume of solution takes to tally up that much of the drug in the patient.

i hope that didn't confuse anyone more. :-)

Does anyone know what the easiest way to solve this problem is? Thank you!

Your client ate 60% of a 16 oz steak. The steak is 45% protein. How many grams of protein did your client eat?

I'd use factor label or dimensional analysis on this one.

setting up the logic:

45% or .45x16 oz. = total oz. protein in the entire steak

but the patient ate only 60% of it, so protein he got was .60x.45x16 oz.

but the problem wants that in grams, not ounces, so I have to convert.

So, you can set it up as a factor label string like this, using two conversion factors that you can carry in your head easily:

[.6] [.45] [16] oz [lb/16 oz] [454 grams/lb] = 122.58 grams of protein

--- ounces in the numerator and ounces in the denominator cancel out

--- lb in the numerator and lb in the denominator cancel out

--- you are left with grams, and I get a different answer than the post, above. The reason for that is that she used a rounded off conversion factor of 28.0 grams per ounce, when I didn't round my conversion factors off. How much rounding the nursing instructors allow, I don't know. If she had used 28.35 g/oz, then we'd have gotten the same answer. Use whatever the instructor wants you to use.

i forgot/cant find anywhere how to convert 'units to ml'!!

the question=

physician prescribes 2 U of prbc to infuse over 1 hour each, drip factor is 10 gtt/ml, find drops per minute

i just need to know the conversion of UNITS TO ML, please and thanks

That conversion factor is the concentration of the solution, how much drug per mL of the solution, and it will not always be the same in every problem. In the penicillin problem, the solution that you had to administer had a concentration of 250,000 units per mL, and they actually told you that in the problem. It will vary with each problem. Sometimes, I expect, they will give you the data regarding how they mixed the solution and you'll need to calculate what the units of drug per mL of the solution are, and you'll have to do that first, and then use it in the problem.

The IV calcs are the only ones that I can't set up equations for right off the top of my head yet. That's because I am not in nursing yet and I have to look up the IV vocabulary, and also go look up the conversion factor for number of drops that equal one mL. Chemical engineering uses huge quantities and flow rates, not teeny IV drops, lol.

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For that particular problem, are red blood cells packaged as one unit per 100 mL of solution? (I found that someplace on the Internet. Might be wrong, but let's assume that's what it is for this calculation.

2 U of prbc to infuse over 1 hour each is 1 U per hour, or 100 mL of this prbc solution in an hour, which is 60 minutes. (If the order had been for 2 U per hour, then you'd put the whole 100 + 100 = 200mL in in an hour, but this asked for one U per hour.)

= gtt/min

so then the calculation is:

100 mL of solution x calibration 10 gtt/mL, divided by one hour or 60 minutes = 16.67 gtt/minute, probably round it up to 17 gtt/min to make sure the patient isn't shortchanged

Is that the correct answer? Did I even guess the calculation right, lol??

mL and hour cancel out, leaving 100x10 gtt divided by 60 minutes = 16.67 gtt/minute

Pharmacology Math: Calculating IV Problems is another example.