# Need help on one clinical calculation

Published

so i have been working on this one problem for hours and i feel like it is so easy but i can not get the right answer!!

Medication order: 8 mg in 250 mL. Infuse at 10 mcg/min.

How many mL per hour do you need to infuse to deliver 10 mcg/min

i have been dividing 10mcg/min by 8000mcg then multiplying the answer by 250ml! i can not seem to get the right answer!

Help :)

1,289 Posts

Specializes in Urgent Care NP, Emergency Nursing, Camp Nursing. Has 12 years experience.

Start with your initial concentration, use unit conversions to switch those units to those of the ordered rate, and then convert that into the units required for the answer.

380 Posts

Has 8 years experience.

Not only do you need to converse the rate but don't forget the initial answer is per minutes and you need to muliply times 60 to get the hourly rate. Don't forget to round if needed.

815 Posts

Has 4 years experience.

What answer are you getting? Before I explain it, I got an answer of 18.75(rounded to 18.8 ml/hr), or 19 ml/hr if they want you to round to a whole number. I want to see what answer you're getting so I can see where exactly the mistake is.

210 Posts

Has 2 years experience.

I did 250 * 10 and got 2500. 2500/8000=0.3125mL per min, but it wants for an hour. So I multiplied 0.3125 * 60 min and got 18.75mL/hr.

1,289 Posts

Specializes in Urgent Care NP, Emergency Nursing, Camp Nursing. Has 12 years experience.
I did 250 * 10 and got 2500. 2500/8000=0.3125mL per min, but it wants for an hour. So I multiplied 0.3125 * 60 min and got 18.75mL/hr.

Why are you doing the OP's homework for them?

87 Posts

Specializes in Aspiring for a CCRN.

Next time you face a math block, remember to pick apart the prompt. I'm using dimensional analysis.

1. Medication order: 8 mg in 250 mL - This is the medication concentration.

2. Infuse at 10 mcg/min. - This is your infusion rate of this particular medicine.

3. How many mL per hour do you need to infuse to deliver 10 mcg/min? - Now, these are your desired units for which you'll have to now find the quantity. This also is a rate just like the 2, but the only difference is the units.

Being able to convert back and forth serves a very important function. Not all machines are made to measure the same thing or the medications made to deliver the therapeutic dosage in the same units.

mL/hr = (250 mL / 8 mg) x (1 mg / 1000 mcg) x (10 mcg/min) x (60 min / 1 hr)

Mechanics (punching in the numbers in calc) is not of the importance when you are stuck in a thought process. Read the problem and think about what the prompt means and wants, and how you should set it up to get to the target. Train to think step-by-step in a logical fashion.

Keep practicing and good luck.

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