Hello all,I'm getting ready to start my second semester of nursing school of the 22th of this month. Eash semester we must take a calculations exam....I have always had problems when it came to problems with grains......I'm looking over my practice exam..and dont have a clue how to set up or do this grains problem....can someone show me how to set up grains problems..and how to solve them.
My school uses the formula.....gr i = 60 mg or gr vx = 1000mg.
Here is the problem.
Order NTG gr 1/150 IV stat. Available: NTG 0.4 mg/ml. How many ml's will you give?
Specializes in med/surg, telemetry, IV therapy, mgmt.
the kindest thing you can do for yourself is to learn how to do these problems using dimensional analysis. there are links to tutorials on how to do medication calculations as well as dimensional analysis on post #3 of this thread:
order ntg gr 1/150 iv stat. available: ntg 0.4 mg/ml. how many ml's will you give?
dose desired
: grain 1/150
dose on hand
: 0.4 mg/1 ml
1 ml/0.4 mg
(dose on hand)
x 1 grain/`150
(dose desired)
x 60mg/1 grain
(conversion factor)
=
1 ml
(amount to give)
now, when i set up this problem, the dose desired and dose on hand are quantities (marriages) that must remain together. they are ratios, or fractions, that can be expressed with either term in the numerator or denominator. it doesn't matter which is in the numerator or denominator for a dimensional analysis equation as long as the "marriage" remains intact. you want to manipulate the numerators and denominators of these marriages in order to factor out (cross out, multiply out) the
labels
("grains", "mg", "ml")attached to the numbers. the idea is that you only want to be left with
specific labels
on the
final answer
. in this case, you want the label "ml" on the final answer. so, i set up the problem and manipulated the quantities i had to work with so everything was going to factor out except for the label, "ml's". i also added the conversion factor because you need that as well to get rid of "grains" and "mg" on these numbers. then, it was just a matter of doing the math with the numbers.
the easiest way that i have found to do these is to take the 60 grains divided by the order which in this case is 150 then divide that by what is on hand which here it is 0.4, so you have
Thanks so much Pixie! I just quoted your last post to my classes fourm... we were just talking about grains today and people were lost... i know this will help...
Thanks so much Pixie! I just quoted your last post to my classes fourm... we were just talking about grains today and people were lost... i know this will help...
Daytonite, BSN, RN
1 Article; 14,604 Posts
the kindest thing you can do for yourself is to learn how to do these problems using dimensional analysis. there are links to tutorials on how to do medication calculations as well as dimensional analysis on post #3 of this thread:
you will also find all kinds of problems already worked out that you can look at on this thread: