Help with IV infusion rate answer

Published

Here is the question. Please keep in mind this is the first time doing these and I was never given any advice on how to set these problems up

The conversion I have volume/time x drop factor (gtt/ml)= IV flow rate

Physician ordered 3 grams of zosyn in 250DW5 to infuse at 100mcg/kg/min IVPD. Patient weights 110kg. At what rate in ml/hr will you set infusion device?

The answer I keep on getting is 55,000 which is not an answer to choose. So I think I may need help as I do not know how to start this problem.

Rose_Queen, BSN, MSN, RN

6 Articles; 11,269 Posts

Specializes in OR, Nursing Professional Development. Has 18 years experience.

The issue is the formula you are using. Drop factor doesn't apply here unless you aren't running it on a pump. And nowadays, everything is pretty much run on a pump. So, break it down: 100mcg/kg/min. How many mcg need infused in a minute? Try that and go from there until you have ml/hr. This is where dimensional analysis comes in handy.

SilleLu

150 Posts

Has 3 years experience.

So the question is asking...at what rate in ml/hr will you set the infusion device? In other words, how many ml of the fluid with med will be pumped into your patient if it ran a full hour? Now think about the answer you are getting...55,000. So you would be putting 55 one liter bags into your patient in an hour...seems odd, huh?

Now my poinnt is, sometimes you have to set aside the "math" for a second and think, does the answer I'm getting even make sense? In this case, nope. This way of thinking will save you many wrong answers...An example I have from school....one time I got an question that was asking for ml for IM injection...now the max for IM injection per muscle was 3ml we were taught (only 1 ml in deltoid). So when I worked the problem, the answer came out to 30 ml. 10 IM injections for one order....that can't be right...searched and found missing decimal.

Good luck, work the problem one conversion at at time. Show a little of your work here and we'll be able to help more....

I had a hard time using straight dimensional analysis when it came to these questions. I relied on a formula from my book that works perfectly every time. Ordered mg/kg/min x patient's weight in kg x 60 (divided by) mcg/mL. So the first thing I go is find out how many mcg/mL by using the proportion method. There are 1,000,000 mcg in 1 gram, so 3 grams of Zosyn is equal to 3,000,000 mcg. To set up the proportion I would do this... 3,000,000 mcg : 250 mL :: x mcg : 1 mL Then multiply the insides and the outsides to get 250x = 3,000,000. Then divide 3,000,000 by 250 to get x = 12,000 mcg/mL. Now plug that into the equation. I first mentioned. 100 mcg/kg/min x 110 (patient's weight in kg) x 60 divided by 12,000 mcg/mL. The answer you get is 55 mL/hr.

I don't know why I never got the answer using straight dimensional analysis (probably because I missed steps), but I didn't. I hope I didn't confuse you more, but if you are comfortable with the formula and the proportion method, this way of calculating will always work out! Good Luck!!!!!

MendedHeart

663 Posts

••••••

Specializes in MICU. Has 3 years experience.

100 mcg x 250 ml x 1 grams x 1 ml x 60 min​ x 110 kg = 55ml/hr

kg/min 3 grams 1000 mg 1000mcg 1 hour

SilleLu

150 Posts

Has 3 years experience.
100 mcg x 250 ml x 1 grams x 1 ml x 60 min​ x 110 kg = 55ml/hr

kg/min 3 grams 1000 mg 1000mcg 1 hour

loveofrn, please don't do someone's homework for them, the purpose of these boards is to ASSIST...students must show their own work, thoughts, etc. to get help with problems...

Meeshie

304 Posts

Here. This is a video on how to do the calculations.

Practice it. :) The DA method will allow you to do any calculation you need once you get it down.

KelRN215, BSN, RN

1 Article; 7,349 Posts

Specializes in Pedi. Has 16 years experience.

I'm sorry, I just gotta ask... who in the hell orders Zosyn like this? 4 1/2 hours to infuse a dose of Zosyn? Dosed in mcg/kg/min? I work in peds where everything is weight based and Zosyn is dosed at 80-100 mg/kg q 8hr based on the piperacillin component. It is infused over 30 minutes, not 4 1/2 hours. Everything about this problem is wrong.

Specializes in Emergency/Cath Lab. Has 6 years experience.
I'm sorry, I just gotta ask... who in the hell orders Zosyn like this? 4 1/2 hours to infuse a dose of Zosyn? Dosed in mcg/kg/min? I work in peds where everything is weight based and Zosyn is dosed at 80-100 mg/kg q 8hr based on the piperacillin component. It is infused over 30 minutes, not 4 1/2 hours. Everything about this problem is wrong.

For awhile we were doing zosyn doses over 4 hours but went back to 30 minutes. But yeah, super strange order, but apparently it did work by making them math.

ixchel

5 Articles; 4,547 Posts

Specializes in critical care.

"Call pharmacy and ask why in the world they would send such a jacked up med label." :)

nynursey_

642 Posts

Specializes in Med/Surg/ICU/Stepdown. Has 3 years experience.

FYI, depending on CrCl, Zosyn is run over 4 hours.