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Patient weighs 170 pounds who requires a dopamine drip. Need calculation help!

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I have this due on Tuesday which is my first day back. I feel as though I have forgotten all of my calculations. Here is the problem and how I did it. Please tell me if I did it correct or where I went wrong.

Pt. weighs 170 pounds who requires a dopamine drip for a failing kidney. Protocol dictates that you start the drip at 5mcg/kg/min. You want to mix a drip that contains 400 mg of dopamine in your 250 ml bag of normal saline. How many ml/hr will you infuse?

170/2.2=77.27=77.3 kg

77.3 kg* 5mcg/min*60 min= 23190mcg/min=.057 round to .1*250ml=25ml/hr

400000mcg 400000 mcg

Not sure if I did any of this correct. Help.

loveofrn, BSN, RN

Specializes in MICU. Has 3 years experience.

The answer is 14.5ml/hr

loveofrn, BSN, RN

Specializes in MICU. Has 3 years experience.

How did you get 0.57

And again why did you round 0.057 to 0.1

loveofrn, BSN, RN

Specializes in MICU. Has 3 years experience.

Ok here is how I did mine

(5mcg/kg/min)×(250ml/400000mcg)×(60min/hr)×(77.3kg)=14.5ml/hr

That was my original answer. I originally converted the 23190 mcg to mg then divided that by 400mg then multiply by 250ml

23.19*250ml=14.49=14.5

400

Is that the correct way?

I did not come out with 0.057. I did 23190

400000

I converted the 400mg to mcg. Not sure why.

loveofrn, BSN, RN

Specializes in MICU. Has 3 years experience.

Always check your unit whenever you are doing dosage math. Also do you know how to use dimensional analysis

loveofrn, BSN, RN

Specializes in MICU. Has 3 years experience.

And your answer is correct

loveofrn, BSN, RN

Specializes in MICU. Has 3 years experience.

Yes you suppose to convert 400 mcg to mg to track your unit

It was 400 mg to mcg. By the way, I hate dimensional analysis. Just do.

loveofrn, BSN, RN

Specializes in MICU. Has 3 years experience.

Lol just make sure you know what you are doing. Just stick with the method that works for you

Thanks so much for your help.

loveofrn, BSN, RN

Specializes in MICU. Has 3 years experience.

You're welcome

pmabraham, BSN, RN

Specializes in Hospice, Palliative Care. Has 3 years experience.

Good day, b747girl5:

Generally you don't want to round until the end to avoid mistakes.

Thank you.

Kuriin, BSN, RN

Specializes in Emergency. Has 5 years experience.

Unless stated otherwise, you should do as pmabraham said and round only at the end.

I did this

170lbs = 77.3 kg

5mcg/kg/min= 3865mcg/min

which converts to 0.3865 mg/min

then

400 mg/ 250 ml = 0.3865 mg/x ml

and cross multiply

x = 0.24 ml/ min

multiply by 60 to get 1 hour

14.493 rounded to 14.5 ml/hr

The answer is 14.5ml/hr.

400mg=400,000 mcg

170 lbs=77.3 kg

(77.3 kg * 5 mcg/kg/min=387 mcg/min)

(387 mcg/min * 60 min/hr=23,220 mcg/hr)

(250 ml/400,000 mcg * 23,200 mcg/hr)=14.5 ml/hr

Hope the break down helps.