Help with a drug calculation problem

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Specializes in ICU.

Hi everyone!

Well we're having another drug calculations exam next week and fortunately, we were given a practice test to help prepare.

I am having difficulty understanding one problem in particular:

Order: Heparin 7500 units IVPB in 500cc N/S to run @ 50 units per hour.

Set the IV pump at ____ cc/hr to deliver 50 units/hr.

Now, I do know that the correct answer is 3.33 cc/hr per the key that was provided, but I can not understand why this is. Can someone please be so kind as to explain? :trout:

Thanks so much in advance!

Janet

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hey there.

you want to do a proportion pretty much (well.. this is how i like to do it)

it's 7500 units/500cc

sooo.. since you want 50units/hr

7500units 50units

500cc x

----------------->cross multiply to get:

7500x=25000

Divide each side by 7500

You get 3.33

Make sense?

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Specializes in med/surg, telemetry, IV therapy, mgmt.
order: heparin 7500 units ivpb in 500cc n/s to run @ 50 units per hour.

set the iv pump at ____ cc/hr to deliver 50 units/hr.

dose desired: 50 units of heparin/1 hour

dose on hand: 7500 units in 500cc of normal saline

you want to get the dose to give expressed as cc/hour.

50 units/1 hour
(dose desired)
x 500cc/7500 units
(dose on hand)
= 3.33 cc/hour
(dose to give). however, you would actually set the pump at
3cc/hour
since most pumps, except some of the very new and sophisticated ones, can only be programmed with whole numbers.

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Specializes in ICU.

Aha--that makes sense! I could plug in the numbers to get the answer as was provided on the key, but just needed it explained for clarity. Thanks!!! :idea:

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