Need help with Dosage calculations PLEASE!!

XIGRIS · Oct 29, 2004

The order is to give Ativan 3mg IV Push. So the formula is Desire / Have X Quantity.

3mg/4mg X 1 ml = .75 ml.

The infusion rate you got 2mg/ml is the drip rate.

The order is to give 3mg 20 min prior to surgery.

kwagner_51 · Oct 29, 2004

I need some help with these problems. I don't even know where to look on the net for help!!
Here they are:
1. Ordered: Ativan 3 mg IV push 20 minutes pre-op
Available: Ativan 4 mg/ml with drug literature guidelines of "IV infusion not to exceed 2 mg/min."
How much Ativan should you prepare?
2.
Order: Ativan 3 mg IV push 20 minutes pre-op.
Available: Ativan 4 mg/ml with drug literature guidelines of "IV infusion not to exceed 2 mg/min."
What is a safe infusion time?
Thank YOU so much!!

The answers are 1. The answer is 0.75 cc. 2. The answer is 1.5 minutes.

My problem is HOW DID they get the answer to the second one? The first one I had right, I just didn't put the space in between the # and the cc's. :angryfire

Thanks again!!!

crb613, BSN, RN · Oct 29, 2004

I need some help with these problems. I don't even know where to look on the net for help!!
Here they are:
1. Ordered: Ativan 3 mg IV push 20 minutes pre-op
Available: Ativan 4 mg/ml with drug literature guidelines of "IV infusion not to exceed 2 mg/min."
How much Ativan should you prepare?
2.
Order: Ativan 3 mg IV push 20 minutes pre-op.
Available: Ativan 4 mg/ml with drug literature guidelines of "IV infusion not to exceed 2 mg/min."
What is a safe infusion time?
Thank YOU so much!!

I am not the best at this but I will try to help cause I know how it feels not to be able to figure these thing out.I use dim. analysis ml= 1ml/4mg x 3mg/1=3/4=0.75ml.You set it up to cross cancel start with what you want your ans. to be (ml) that's what's aval.So ml= (what is with that? 4mg) ml=1ml/4mg now your dose order 3mg/1. mg's are on top and bottom oppsite each other and cancel out ( only the letters mg not the numbers) what is left are the letters ml. When you have the same letters on each side of the = sign you have canceled right.Now just multiply across the top and then the bottom and divide these two. 3x1=3 top 4x1=4 bottom 3/4=0.75ml ( I'm using the / for the division sign).

On the second part if it's not to exceed 2mg/min wouldn't you run 3mg/2min?

That would make 1.5mg/min not over the amount. I hope I have not confused you,and on the infusion times we are not doing those yet but this just made sense to me. Good Luck!!

lil' girl, LPN · Oct 31, 2004

we do proportions like, 4mg/1cc 3mg/xcc and cross multiply, 4x=3 because 1x3=3, then divide 3 by 4 to get 0.75cc

second one is the same answer 0.75 cc and done the same way, and again, 2mg/1min 3mg/xmin cross multiply 2x=3 because 1x3=3 then divide 3 by 2 to get 1.5 min