Help with a dosage problem

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How do I work out this medical dosage math problem :1,000 mg of Dobutamine in 250 cc of D5W has been ordered IV for infusion at a rate of 12.5 mcg/kg/min. Your patient weighs 190 lbs. At how many microdrops/min. should youinfuse the IV using a solution administration set that delivers 60 microdrops/cc

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Specializes in Critical Care, ED, Cath lab, CTPAC,Trauma.

http://www.dosagehelp.com/

http://www.unc.edu/~bangel/quiz/testfluh.htm

http://www.manuelsweb.com/nrs_calculators.htm

desired dose

----------------------

available dose

x

quantity

----------------------

1

= volume to be given

common drop factors are:

10 drops/ml (blood set), 15 drops / ml (regular set), 60 drops / ml (microdrop).

to measure the rate we must know:

(a) the number of drops

(b) time in minutes.

the formula for working out flow rates is:

volume (ml) x drop factor (gtts / ml)

---------------------------------------------

time (min)

= gtts / min

(flow rate)

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if you have the correct answer, can you post it? i just tried doing this problem - I'd like to know if I got it right. If I did I'll post my steps if you still need them.

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Specializes in Critical Care, Emergency Medicine, Flight.

wow i just tried this and dont think i did it right...lol

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i keep checking back for the answer, i want to know!

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Specializes in Vascular Access.

16.19 mls/hr or if running to gravity, 16.19 gtts/min.

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16.19 mls/hr or if running to gravity, 16.19 gtts/min.

woohoo that was the answer i got but the question asks how many microdrops/min, so would 16.19 still be the correct answer?

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with microdrips, drops per minute equals cc per hour. that's because there are 60gtts per cc (it says so right on the box) and 60 minutes in an hour.

sit down with some paper and a pencil and draw yourself some pictures about that.

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Specializes in Vascular Access.
woohoo that was the answer i got but the question asks how many microdrops/min, so would 16.19 still be the correct answer?

Microgtts per minute always equals 60gtts per ml as this is what mini, or micro gtt tubing is. So, yes, you are correct.. Woohoo!!!

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Specializes in Obstetrics.

OP, do you understand how to get the answer?

I use the D/H x V method.

1,000 mg of Dobutamine in 250 cc of D5W has been ordered IV for infusion at a rate of 12.5 mcg/kg/min. Your patient weighs 190 lbs. At how many microdrops/min. should youinfuse the IV using a solution administration set that delivers 60 microdrops/cc

In this problem, you first have to change pounds to kilograms so 190/2.2=86.36 kg. Since the drug comes in 12.5 mcg/KG/min, you need to multiply the 86.36kg by 12.5mcg which gives you 1079.54. This is now your desired amount. You also need to change 1000mg to 1000000mcg (which is your on hand).

Your problem is then 1079.54mcg/1,000,000mcg=0.00107954mcg. You will multiply this by 250ml (your vehicle) which gives you 0.2698863ml. You need to get ml/hr so you will multiply that last number by 60 which gives you 16.19 which you'll round to 16.2ml/hr and what you'll set the pump at.

Hope this helps some and isn't too confusing.

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