Dimensional analysis

Published

Our instructors insist on us using dimensional analysis. I like the fractional method. Or ratio proportion. Now when I look at a dosage calculation problem, I become dyslexic and all the numbers make no sense because I am trying to figure out how to plug them in to the DA format and of course our tests are timed so I get stressed from the pressure of taking too long staring at the problem waiting for it to make sense to me. :banghead: Any tips on figuring out DA?

I'll just tell you that this is probably against advice of a lot here, but I am good at math and refuse to do DA. I hate it! I've been doing the math the same way for 20+ years and just don't want to do it any other way. If it ain't broke don't fix it and that's just how I feel about it. I have scored very high on any of my nursing math tests and I've yet to see a compelling reason to change how I solve my math problems. So, what I do when I have to listen to DA discussions with other students is I honestly do my very best to tune them out and that's how I handle things. Like I said maybe not the best advice, but to me if you know what you are doing using ratio/proportions and are comfortable with that then don't feel bad about continuing it to do it that way. I think the important thing is if you can figure out the math correctly and quickly and not which method you use to solve it.

Up Vote Up Vote ×
Specializes in Pediatrics, Emergency, Trauma.
I'll just tell you that this is probably against advice of a lot here but I am good at math and refuse to do DA. I hate it! I've been doing the math the same way for 20+ years and just don't want to do it any other way. If it ain't broke don't fix it and that's just how I feel about it. I have scored very high on any of my nursing math tests and I've yet to see a compelling reason to change how I solve my math problems. So, what I do when I have to listen to DA discussions with other students is I honestly do my very best to tune them out and that's how I handle things. Like I said maybe not the best advice, but to me if you know what you are doing using ratio/proportions and are comfortable with that then don't feel bad about continuing it to do it that way. I think the important thing is if you can figure out the math correctly and quickly and not which method you use to solve it.[/quote']

You must go to a program that doesn't grade on DA.

I used ratio proportion for many years as a LPN...until I went through my BSN program where if you did not set the math portion as a DA, it was marked incorrect; even if you got the answer; the point was with factor-labeling the amount of med dosage errors decreased by using the DA model.

Now that I have been using it, it is much MORE better than ratio proportion; Music gave a GREAT presentation above in how to use it on the fly. :yes:

Up Vote Up Vote ×
Specializes in Pediatrics, Emergency, Trauma.

A little EBP for the benefits of DA and the reduction of med errors:

http://www.ncbi.nlm.nih.gov/m/pubmed/16496864/

Up Vote Up Vote ×
You must go to a program that doesn't grade on DA.

I used ratio proportion for many years as a LPN...until I went through my BSN program where if you did not set the math portion as a DA, it was marked incorrect; even if you got the answer; the point was with factor-labeling the amount of med dosage errors decreased by using the DA model.

Now that I have been using it, it is much MORE better than ratio proportion; Music gave a GREAT presentation above in how to use it on the fly. :yes:

Yes, my school taught us 3 different methods and told us to choose the method that worked best for us. They told us that if we were already used to doing it one way not to try to switch and that was good enough for me. I am not opposed to learning new things. I just find math though is very hard for me to switch to another method and hadn't been given a compelling reason to switch. I will take a look at your research article because I'm honestly not totally hardheaded.

Up Vote Up Vote ×
Why does this matter?

You might find yourself in the position I did 2 shifts back... in a room with a 3rd year resident and 2 our most senior attendings and the assistant nurse manager and another one of our top-flight nurse when...

The doc hands me a bag of meds and says, "give her 12 mg of etomidate now. We'll shock her twice. If she doesn't convert, we're going to intubate with 24 of etomidate and 140 of roc." I'm looking down at two vials of etomidate which are labeled 40 mg/20 mL.

How much do I give the first dose?

How much the second?

No pen, no paper... and no time. I either do it, and do it right... just like the docs do... or I hand it over to somebody else and step back out of the way.

40 mg per 20 mL means 2 mg per 1 mL which means 12 mg per 6 mL and 24 mg per 12 mL.

I pulled up 6 mL in one syringe and 12 mL in the other syringe.

I do my thing, the doc tubes her, and I take care of her for the next several hours until I wheel her up to the ICU... My patient from the time she rolled in the door until I handed her off to the unit.

See I would have solved it just like you, but I never considered that DA. I usually just break it down like that in my head and convert. I have always considered DA setting things up in a formula. Maybe I've just had DA poorly explained to me.

Up Vote Up Vote ×

To me, it matters not ~how~ one arrives at the answer just so long as they can... every single time, without fail.

Fundamentally, all the 'different' ways of solving these problems are just simple algebra... equalities, substitutions, and inverse operators.

Up Vote Up Vote ×
Specializes in Hospice.
Yes, my school taught us 3 different methods and told us to choose the method that worked best for us. They told us that if we were already used to doing it one way not to try to switch and that was good enough for me. I am not opposed to learning new things. I just find math though is very hard for me to switch to another method and hadn't been given a compelling reason to switch. I will take a look at your research article because I'm honestly not totally hardheaded.

LOL I totally agree with you! If I get the same answer using ratio:proportion why does it matter?! But it does, so I am learning it. :banghead:

Up Vote Up Vote ×
Specializes in Hospice.

BTW Music, you are awesome.

Up Vote Up Vote ×
+ Join the Discussion