IV rate calculations with DRD??

[SusGob711]

I need help with a question for my adult health nursing course. I'm comfortable calculating IV rates given volume to be infused, time, gtt/min, etc. but our latest questions include another piece of data I'm not sure what to do with: DRD (drip rate denominator?). How does this influence the calcuation? Our instructor gave us at least a dozen of these and I don't know how to do them. Thanks for any help!!

Here's one of our problems:

Order: 1000 mL D5NS with KCl 40 meq to be infused in four hours

Drop factor: 15 gtt/ml with DRD=4

Run IV at what rate on the pump? (ml/h)

a) 100 mL/h

b) 200 mL/h

c) 150 mL/h

d) 250 mL/h

[MotivatedOne]

I'm not sure if your instructor is trying to trip you up or what but it's a simple calculation. Neither the drop factor or the DRD (something I've never heard of) is needed to calculate the problem. 1000ml/4hr = 250ml/hr. The only time I've used the drop factor was when I was trying to calculate the gtt/min. Then it would be (1000 x 15)/60(4) = 62.5 or 63 gtt/min.

Good luck finding out what the DRD is or how it's used...please repost when you do!

Thanks :-)

[pecanpies]

I agree with MotivatedOne - the drop factor (never heard it called DRD) is a distractor. You don't need it to answer the question.

[Double-Helix, BSN, RN]

The above poster is correct that you don't need either the drop factor or the DRD to calculate the answer. Nursing instructors love to throw in extra information in order to trip you up. When you get a question like this, carefully read it and circle the information that you need in the question. Ignore all the rest.

For future reference, the DRD is another way you can calculate the drops per minute. DRD is based on the drop factor. You find the DRD by dividing 60 by the drop factor. So if your tubing has a drop factor of 15 gtt/mL you do 60 / 15 = DRD 4. Here's a helpful chart:

60 drops per ml = DRD 1

30 drops per ml = DRD 2

20 drops per ml = DRD 3

15 drops per ml = DRD 4

12 drops per ml = DRD 5

10 drops per ml = DRD 6

So to use the DRD to calculate drops per minute, you divide the mls/hr by the DRD. So in your question, if you needed to know drops per minute, you would take your total volume to be infused and divide by your number of hours. The divide that answer by the DRD to get your drops per minute.

I know this was a lot of information. Hope it helped!