Medication Math

[kenyon]

I cannot figure out the answer to the following question - every time I try, I keep getting different answers - please help me solve it/work it out.

I have to administer 140mg IV Lasix in 50 mL. Knowing that I can infuse a maximum of only 4mg/min a) how should I program the pump (drops/min) and b) how long will the drug infuse over?

[nurseprnRN, BSN, RN]

Normally we ask students to show us their calculations so we can help them identify where they went wrong. Could you show us what you did that keeps coming out wrong?

This is a multi-factorial problem- you will need to do several different operations to get it all done.

HINT: Before you start, you need to know:

How many mg/ml in your initial baggie

How many gtts/ml your IV set delivers

How many minutes in an hour :)

Does that help you get started?

[kenyon]

I calculated 2.8mg/mL

Since the IV set is 10 gtts - I calculated 8.33 gtts/mL

After this I get totally confused - I don't know where to go with it now - everytime I look at it I get more confused

[kenyon]

My answer would be 2.8 ml/hr for the rate and the total infusion time is 2.33 hours- but I am not sure what the formula is as to how I'm arriving at these numbers or if I am anywhere near the right answer - I think i'm over thinking the questions and missing the answer all together

[203bravo, MSN, APRN]

Kenyon -

Work it out step by step.

1st if you give 4 mg / min how long would it take to give 140 mg?

2nd multiply the total volume of solution to be infused by the drop factor then divide by the total time of infusion (answer to step 1)

edit to add: do you need to figure out the mL / hr? it's not listed as part of the question. But would be good practice even if you don't.

[203bravo, MSN, APRN]

PS: remember when rounding for gtts - it is normally accepted to round this number to a whole number since you cannot give a partial drop of fluid :)