Dosing Calculation ... help!

[grensa]

I need help with a dosage calculation. The problem is as follows:

The order is for demerol 35mg with versed 0.6mg IM prior to a colonoscopy. Available to the nurse is demerol 50mg/ml and versed 1mg/ml. The nurse would administer a total of how many ml's?

I am totally stumped on this one. Can someone please tell me how to set up this problem? Thanks!

[Anothertry]

Ok I just re-read the OP. Thanks!

[mfce175f]

Sorry for the silly question but I was just wondering...when nurses have a lot of calculations to figure out do they usually do them in their head on the fly or do they have a calculator with them all the time?

I think most med carts have a calculator. Personally I always have one with me because I would double check even if I did figure it out in my head. I need to see it also!

[Double-Helix, BSN, RN]

I think most med carts have a calculator. Personally I always have one with me because I would double check even if I did figure it out in my head. I need to see it also!

We don't have med carts. We have a central pyxis machine. I always double check my calculations via calculator unless it's super simple like 1 mg in 1 mL and I want to give 0.5 mg or the dose is 500 mg and I have 250 mg pills or something similar. If it's really complicated, like a drip rate, I usually do it on paper as well because it helps me to visually see the formula.

[nurseprnRN, BSN, RN]

"the order is for demerol 35mg with versed 0.6mg im prior to a colonoscopy. available to the nurse is demerol 50mg/ml and versed 1mg/ml. the nurse would administer a total of how many ml's?"

ok, now, let's just stop a minute and break this down. eyeballing for reasonableness is always a good idea before you start putting together any sort of equation. what sort of numbers are you expecting? big ones? small ones?

first, the demerol part (and btw, it's time for your faculty to get a new test question bank-- nobody uses that crap anymore, it's awful ). (also properly capitalized, since it is a trade name for meperidine.)

demerol comes in 50mg in 1 cc. you want 35mg. eyeball that. do you want more or less than 1cc? less, of course. good.

now can you figure out the volume of demerol that is 35mg? suppose they had asked for 25mg, you could eyeball that and figure, "gee, one half cc!" right? because you would put 25mg/50mg and come out with 1/2 (0.5). (25mg is 50% of 50mg).

well, what happens if you divide 35mg/50mg? when you cancel out your fives or however you want to do your division, you get...7/10 (0.7). (35mg is 70% of 50mg...70% of one cc is 0.7cc.) put that 0.7cc...over there for a minute.

now, look at the versed (properly capitalized, since it is a trade name, for midazolam). using the same eyeballing, you realize that 0.6mg is less than 1mg, so you'll want less than 1cc of that, too. so when you do the arithmetic (it's not, properly, mathematics) and divide 0.6mg/1.0mg, you'll get.... 0.6cc.

add that to the 0.7cc of demerol you put aside earlier (more arithmetic!), and that's 1.3cc.

here's a link to another way of looking at doing calculations. i taught this to my students and it was amazing how fast they got it. (i hope this links)

Med calcs.pdf

[loriangel14, RN]

"I remembered the formula as devil over hell times the lost souls "

Love it!!!

In school we learned it as " doc over stock", doc being what the doc ordered and stock being what we had.

[eagle78]

In school we learned it as " doc over stock", doc being what the doc ordered and stock being what we had.

This is good...