# Urgent small help needed with IV Math! Plzzzzzz

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HI everyone, I am having some real problems with one sort of IV math problems. These are practice math problems. I have been nearly stuck on them for about 2 hours trying to figure out how to solve them, unfortunately I still don't know how. I really need help, please any assistance truly appreciated! The problems are:

1. The physician orders dopamine at 5 MG/Kg/min. The concentration is dopamine 2 g in 250 mL of 0.9% NS. The patient's weight is 80 kg. How many mL/ h should the IV pump be programmed for? The answer is 3 mL.

5x80x60 over 8000. But where does 8000 come from???

2. The physican orders dobutamine at 12 MG/KG/min for a patient weighing 75 kg. The concentration is dobutamine 1 g in 250 mL of D5W. How many mL/h should the IV pump be programmed for? The answer is 13.5 mL.

12x75x60 over 4000. But where does 4000 come again from?

Specializes in Medical and general practice now LTC. Has 32 years experience.

Moved to the general student discussion forum

Check out the sticky we have on maths you may find it helps you

I REALLY NEED HELP!! i'm feeling very frustrated!

the formula for solving this type of problem is: dose x weight x 60 / concentration per ml. the 8000 and 4000 are the concentrations of dopamine and dobutamine respectively.

when setting up this type problem you need to ensure that you are using the same units for both the dose and concentration.

i hope this information was helpful.

But if I can know more specifically how 4000 and 8000 arises that would be very helpful. I tried again, but still don;t get it. I feel very dumb.

hi everyone, i am having some real problems with one sort of iv math problems. these are practice math problems. i have been nearly stuck on them for about 2 hours trying to figure out how to solve them, unfortunately i still don't know how. i really need help, please any assistance truly appreciated! the problems are:

1. the physician orders at 5 mg/kg/min. the concentration is dopamine 2 g in 250 ml of 0.9% ns. the patient's weight is 80 kg. how many ml/ h should the iv pump be programmed for? the answer is 3 ml.

5x80x60 over 8000. but where does 8000 come from???

2. the physican orders dobutamine at 12 mg/kg/min for a patient weighing 75 kg. the concentration is dobutamine 1 g in 250 ml of d5w. how many ml/h should the iv pump be programmed for? the answer is 13.5 ml.

12x75x60 over 4000. but where does 4000 come again from?

hi everyone, i am having some real problems with one sort of iv math problems. these are practice math problems. i have been nearly stuck on them for about 2 hours trying to figure out how to solve them, unfortunately i still don't know how. i really need help, please any assistance truly appreciated! the problems are:

1. the physician orders at 5 mg/kg/min. the concentration is dopamine 2 g in 250 ml of 0.9% ns. the patient's weight is 80 kg. how many ml/ h should the iv pump be programmed for? the answer is 3 ml.

5x80x60 over 8000. but where does 8000 come from???

2. the physican orders dobutamine at 12 mg/kg/min for a patient weighing 75 kg. the concentration is dobutamine 1 g in 250 ml of d5w. how many ml/h should the iv pump be programmed for? the answer is 13.5 ml.

12x75x60 over 4000. but where does 4000 come again from?

are you sure these problems aren't supposed to be written as 5 mcg/kg/min and 12 mcg/mg/kg? if they are, then i got the same answers as your answer key:

5 mcg x 80 kg = 400 mcg/min

400 mcg x 60 min (in 1 hr) = 24000 mcg/hr

convert: 24000 mcg = 24 mg, 2 g = 2000 mg

set up ratio with dopamine concentration:

2000:250 = 24:x

2000x = 6000

x = 3 ml/hr

12 mcg x 75 kg = 900 mcg/min

900 mcg x 60 min = 54000 mcg/hr

convert: 54000 mcg = 54 mg, 1 g = 1000 mg

ratio:

1000:250 = 54:x

1000x = 13500

x = 13.5 ml/hr

Specializes in NICU. Has 10 years experience.

Yeah, the orders should both be mcg, not mg. When calculating the rate, your denominator is the concentration of the drug -- therefore:

dopamine 2 gm (= 2000 mg = 2,000,000 mcg) in 250 mL NS = 2,000,000/250 = 8000 mcg/mL

dobutamine 1 gm (= 1000 mg = 1,000,000 mcg) in 250 mL D5W = 1,000,000/250 = 4000 mcg/mL

Specializes in Medical and general practice now LTC. Has 32 years experience.

The formula should read as ml/hr= total volume to be infused over total amount of drug x dose x weight x 60

Is the dosage right MG and not MCG?

but if i can know more specifically how 4000 and 8000 arises that would be very helpful. i tried again, but still don;t get it. i feel very dumb.

4000 and 8000 are the concentration of the medications in your problems.

the concentration is generally noted on the package over-wrap as well as the bag itself; however you should know how to determine this. on the packaging, it is typically listed as both the total amount of medication added to the total volume, as well as a concentration per ml.

to determine the concentration of your medication all you need to do is divide the total amount of medication by the total volume of fluid. this will give you the concentration per ml. remember to convert both the dose and concentration to the same unit.

for example, using the information provided in your original post:

dopamine: 2 g/250 ml = 0.008 g/ml or 8 mg/ml or 8000 mcg/ml.

dobutamine: 1 g/250 ml = 0.004 g/ml or 4 mg/ml or 4000 mcg/ml.

it has been my experience that most people refer to the medication in its concentration per ml, and in the unit used for dosing; for example dopamine, 8000 mcg/ml.

i hope this information was helpful.

Specializes in Medical and general practice now LTC. Has 32 years experience.

My working out for the first question

1 mcg = 250

2000000

dose required is 80 (pt weight) x 5 = 400

250 x 400 = 0.05

2000000

0.05 x 60 = 3

The formula should read as ml/hr= total volume to be infused over total amount of drug x dose x weight x 60

This is interesting. I don't think I have ever seen this type of problem worked this way.

I will definitely add this to my bag of tricks.

Thanks.

Specializes in Medical and general practice now LTC. Has 32 years experience.

You are welcome

Specializes in Medical and general practice now LTC. Has 32 years experience.

posts 6 and 7 merged with thread in student section

you multiply dose x kg x min == your total dose ordered

You look at the concentration of the drug dose. In this case it is 2 g per 250 ML.

You need to see how much dose would be in one liter, in this case 4x250=1000 which will be 8 grams in one liter.

Now from the calculation on the first line, you have to have 24000 mg which is 24 g total ordered. You need to have three bags to deliver the order given. You divide the three bags in one day.

Punch it in on the Baxter-It'll figure it out for you. No, really, the only way to get good at the equations is to do a ton of them-I used to spend hours doing problems until I could do them in my head. The key is to see the big picture, which really comes with experience. If you get a number and it doesn't look right, you have to be able to stop, think, and question it-if not, you can overdose a pt-it's not just about math. Also, always double check with another nurse to make sure you're looking at the same thing. Be Safe!!!!!!!!!!

Specializes in Burns/Critical Care/ER. Has 23 years experience.

Rita,

The doses, as ordered, are wrong. In the first case, it should be 5mcg/kg/min, and the in the seconds case, it should be 12mcg/kg/min.

Where does the 8000 come from? In the bottom equation you want to know the concentation per ml. Therefore, you have 2gm (or 2000mg) diluted in 250ml. So, the concentration of mg/ml is 2000mg divided by 250ml = 8mg per ml. Now, you have to convert this to mcg/ml, so you multiply the 8 by 1000 ( since there are 1000 mcg in a mg) giving you the 8000mcg/ml!

Same for the second!!

It's the same a figuring out acid/base equation!!