Med Math

[Kaweah]

Help on figuring this out, I'm not sure how to set the problem up using dimensional analysis.

Your client is receiving dopamine 400mg in 500ml D5W running at 18ml/hour through an IV

pump. The client's weight is 145 pounds. How many micrograms/kg/minute is the patient receiving?

Thanks in advance!!! :)

[Rose_Queen, BSN, MSN, RN]

What do you have so far? While we are happy to help, we aren't going to do the work for you.

[Simplistic]

First, let me start off by saying, why are you using dimensional analysis?

Convert pounds to kilograms. 1kg=2.2lbs.

x = 145lbs.

So 145 pounds =65.90 kgs.

[Rose_Queen, BSN, MSN, RN]

First, let me start off by saying, why are you using dimensional analysis?

For some people, that's the preferred method because everything is laid out and units can be cancelled out.

[Kaweah]

I think I was finally able to figure it out.......

rate = 18L per hr. /ml available = 500mL x dose of 400mg =14.4mg per hour

14.4mg/60min x 1000/65.91 kg = 3.6mcg/kg/min

[Kaweah]

It is the required method for my math exam.

[Kaweah]

First, let me start off by saying, why are you using dimensional analysis?

Convert pounds to kilograms. 1kg=2.2lbs.

x = 145lbs.

So 145 pounds =65.90 kgs.

It is the required method for my math exam.

[SopranoKris, MSN, RN, NP]

I think I was finally able to figure it out.......

rate = 18L per hr. /ml available = 500mL x dose of 400mg =14.4mg per hour

14.4mg/60min x 1000/65.91 kg = 3.6mcg/kg/min.

I get the same answer, looks good :)

When I set up dimensional analysis, I always start with the unit that needs to be on the "top" of the fraction and work my way through to eliminate the extraneous units. That way, it's methodical and keeps me from missing any units.

(1000 mcg/1 mg) x (400 mg/500 mL) x (18 mL/1 hour) x (1 hour/60 minutes) x (patient/145 lbs) x (2.2 lbs/1 kg) = 3.6 mcg/kg/hour

[AliNajaCat]

I hear you on DA being "required" for your med math exam.

What happens when the question you must solve doesn't require it? Then what?

[Sassyrose]

If it was anything like my nursing school, you used it anyways! We had to use it. Get the right answer but didn't use DA? Then it's wrong. There's still a way to do the simple ones using DA. The only thing that didn't use it was diluting feedings.