Need Help with a Calculation (should be easy)

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I'm at the very begining stages of calculations. We never went over these, we were just given a packet of sample problems and a packet of questions to answer.

Here is my question that was assigned:

A Nitroglycerin drip is ordered for your patient to control his chest pain. The concentration is 100 mg in 250 cc D5W. The order is to begin the infusion at 20 mcg/min. What is the rate you would begin on the infusion pump?

My question to you guys:

Is the question answered in the question, 20 mcg/min? If not, how do I set this problem up? Any help is appreciated!

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All the infusion pumps I've used must be set in ml/hr.

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I have no idea, like I said this is just a subsection of my class and really have only been taught metric conversions in class. So, all I know is what the problem is...not sure how to do it....

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Specializes in med/surg, telemetry, IV therapy, mgmt.
a nitroglycerin drip is ordered for your patient to control his chest pain. the concentration is 100 mg in 250 cc d5w. the order is to begin the infusion at 20 mcg/min. what is the rate you would begin on the infusion pump?

infusion pumps are almost always programmed at ml's/hour (or, cc's/hour). so, using dimensional analysis. . .

dose desired: 20 mcg/minute

dose on hand: 100 mg/250 ml (or cc's)

conversion factor: 1 mg = 1000 mcg

conversion factor: 1 hour = 60 minutes

20 mcg/1 minute
(dose desired)
x 250 ml/100 mg
(dose on hand)
x 1 mg/1000 mcg
(conversion factor)
x 60 minutes/1 hour
(conversion factor)
=
3 ml/hour
(infusion pump rate)

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Specializes in Med Surg/Tele/ER.

The concentration is 100 mg in 250 cc D5W. The order is to begin the infusion at 20 mcg/min. What is the rate you would begin on the infusion pump

Dose X 60/concertration......

100mg X 1000= 100,000/250=400mcg

20mcg X60 min=1200/400mcg=3ml/hr

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Thank you, it is OK to put Ml/Hour even though it has mcg/hour earlier in the problem? I'm new to this, thanks for you assistance!

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Specializes in med/surg, telemetry, IV therapy, mgmt.
thank you, it is ok to put ml/hour even though it has mcg/hour earlier in the problem? i'm new to this, thanks for you assistance!

read what the question is asking of you carefully. it asks: a nitroglycerin drip is ordered for your patient to control his chest pain. the concentration is 100 mg in 250 cc d5w. the order is to begin the infusion at 20 mcg/min. what is the rate you would begin on the infusion pump? an infusion pump, as i said earlier, is almost always programmed at ml's/hour. so, yes, it is ok to put the answer is ml/hour because you have to in order to answer the question. this is information that you would have to know to complete this problem correctly. this is beginning critical thinking. you can't program a pump to deliver mcg/hour! how do you make the switch? for me, the easiest way is to use dimensional analysis which is also called the factor label method. with factor labeling (dimensional analysis) you manipulate the terms of the problem along with the labels on the numbers of it's terms using conversion factors to get you to the final answer that will have the labels on the final terms that you are looking for. in this case, a number with "ml's" in the numerator and a number with "hours" in the denominator. the problem itself is a simple dose desired divided by dose on hand to get the dose to give with a tweak on the amounts involved because they have to be equalized since they involve unequal units of measurement.

there are links to tutorials on dimensional analysis on the nursing math thread at https://allnurses.com/forums/f50/nursing-math-thread-264395.html. in the past i have also worked out and explained a number of problems like this on the dosage calculation thread (https://allnurses.com/forums/f205/dosage-calculations-88867.html)

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As I said earlier, all the pumps I have used must be programmed in mL/hr. I came up with the same answer of 3 mL/hr - just wasn't confident enough that it was right until someone else posted it.

As an aside, I had these kinds of questions on my NCLEX exam - where I had to convert mcg to mg, etc.

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at least a simple iv pump is not going to accept mcg/h.....the pump runs on a volume mearsurement, not weight.....the really sophisticated ones may have that sort of program.....but these are not being addressed in your question....remember the pump is set for a VOLUME, good luck

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Thank you all so much, I havent steped foot in a hospital yet so I don't know a thing about these pumps. All of that info was very helpful!

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