D&S Question about determining concentration

[memphispanda, RN]

We aren't really taught D&S...we just have to pass the test every semester. We are expected to learn it on our own. So we got our practice problems yesterday, and they are due tomorrow. I have done all of them, but I am not exactly sure how the concentration is supposed to be expressed. I have a D&S book but it isn't very helpful either. So how would you answer the following question:

The patient is receiving 2gm of lidocaine in 500ml of D5W IV. What is the concentration of lidocaine in each milliliter of D5W?

My answer is 0.004gm/1ml or 4mg/1ml. Anyone know if that is the proper form? Or even the right answer? UGH Thanks for any help.

[Genista, BSN, RN]

I got the same answer. You have 2 Grams Lido/500cc of D5W. Convert the 2 grams to mg, and you have 2000 mg Lido/500cc of D5W. That is equal to 20mg/5cc= 4mg/1cc. There are 4 mg of Lidocaine per 1cc of D5W.

I wasn't sure what you meant by "We aren't really taught D&S."

Dosages & something else? Not sure, but I am guessing it is something along the lines of dosages and calculations. My nursing program did include this as part of our study. That's a shame you don't get some class time review as well. We had a workbook with lots of great examples. You might want to pick one up, they're very helpful. Also, this is a neat site for dosages & calcs:

http://www.geocities.com/HotSprings/8517/Quiz/quiz.htm

Good luck!

[memphispanda, RN]

Oops--sorry. D&S is Dosages and Solutions. We get no class time for this stuff...although they have help sessions after class time, but that isn't until after the practice problems are turned in and checked. It's sort of like self-study, which is great in a way, because I understand the calculations pretty well, but it's not so great when they give us NO information about what the standards are for what we are doing. Our senior instructor is out sick, so it's possible we may have gotten more direction had she been in. Thanks for taking a look!