Dimensional Analysis problem

kimmie4476, ASN, RN · Jul 23, 2009

I got .25 for an answer, using 5 mEq as your starting factor x 20mEq on the bottom and 1 ml on the top but I could be wrong

EymieICURN · Jul 23, 2009

I agree with kimmie

kfarinato · Jul 23, 2009

ml= 1ml x 5meq

____ = 0.25ml

20meq

ok it didn't stay formatted. but you get the general idea i hope

ml = 1ml/20meq x 5 meq= 0.25ml

Daytonite, BSN, RN · Jul 23, 2009

kcl 5 meq is to be added to 500 ml's of d5w and infused at 40 ml. per hour. kcl is supplied in a 10 ml. ampule containing 20 meq per ml. how many ml's of kcl should be added to the iv bag?

dimensional analysis is also called

factor labeling

. it is called that because you set up an equation along with the labels on the numbers with the express purpose of manipulating the labels and factoring them out so that the answer will contain specific labels on them. for this problem, you will want to use this formula:

dose desired divided by the dose on hand multiplied by the amount that the dose on hand comes in to get the amount to use. . .

dose desired:

5 meq kcl

dose on hand:

10 ml ampules of

20 meq/ml

set up the equation and calculate:

5 meq

(dose desired)

/20 meq

(dose on hand)

x 1 ml

(amount that the dose on hand comes in)

= 0.25 ml

, rounded up to

0.3 ml

.

the reason the answer is rounded up to 0.3 ml is because most syringes are not calibrated to be able to precisely draw up 0.25 ml. most syringes can only draw up amounts in increments as small as 0.1 ml. this is the kind of answer that is based in real world application. it may also be because of rounding rules. since the dose desired is only one digit, the answer needs to be presented as one place past the decimal point (one digit) which requires rounding up the answer.

ICAN! · Jul 24, 2009

Thanks for the drawn out explanation (that is exactly what I needed); it made the problem more clear to me. I guess all the other numbers in the problem were confusing me. I really appreciate your help.