Peds med math help - making a bag 1/4 NS?

you need to change the numbers they are giving you so everything is the same L to mL and that sort of stuff I would post the work but don't know if id get in trouble

My other question is if you have the answers what did you use to get them?

What did you do to get answers and what were your answers?

We can guide you if you show your work , even if wrong we can point you in the right direction.

Make certain all your units match (use all mL not L & mL)

We went through it briefly in class so I wrote down how she worked it out, I'm just not sure where some of the numbers(bolded in the problems) come from? This is the work:

a) 154/4 = 38.5 mEq/L

38.5/2 = 19.23/4 = 4.8 mL

b) 10/40 x 20 = 5 mL

c) 1000/12 = 83.3 mL/hr - this one I understand.

Thank you so much for your time!

ok so you showed me your work here is mine

lets see if I can do this in the post box

the concentration of NS is 154 mEq/L times 0.25 for 1/4 concentration that gives you 38.5 mEq/L

1ml x 38.5 mEq/L x 1L x 500ml

4 mEq 1L 1000ml =4.8125ml = 4.8

you have to make sure you change over to ml instead of liters

2.) 40 mEq/20 ml 20mEq KCL/L same as 20 mEq KCL/ 1000ml divided by 2 because you are using a 500 ml bag =10 mEq/500ml

20 ml x 10 mEq = 5ml

40 mEq

3 your wanting to give 1L in 12 hrs or 500ml in 6 hrs 500ml/6hrs = 83ml/hr

hope that helps

We went through it briefly in class so I wrote down how she worked it out, I'm just not sure where some of the numbers(bolded in the problems) come from? This is the work:

a) 154/4 = 38.5 mEq/L

38.5/2 = 19.23/4 = 4.8 mL

b) 10/40 x 20 = 5 mL

c) 1000/12 = 83.3 mL/hr - this one I understand.

Thank you so much for your time!

For the first one, for straight NS you have 154 mEq/L. How many mEq in your 500 mL bag? Half of 154, right? So 77 mEq per 500. BUT that is straight normal saline and you want 1/4 normal saline so you divide by 4 and you get 19.25 mEq that you need to add. Your normal saline is available to you as 4 mEq/mL so you divide 19.25 by 4 and you get your 4.8 mL.

The work you present is a little different than how I did it but the answer works out to the same. Your instructor divided by 4 in the first step to figure out how many mEq/L in 1/4 normal saline. She then divided by 2 because your bag is 500 mL and the concentration given is per liter. Then divide by 4 again because you have 4 mEq/mL of normal saline.

For the second one, you need to add 10 mEq to your 500 mL bag because the order is 20 mEq/L. That's where the 10 comes from. 40 mEq/20 mL = 2 mEq/mL so you need to add 5 mL to make 10 mEq.

Thank you both so much!!! It makes a lot more sense now. KelRN215, the way you worked through part A is how I like to work through my problems, so thank you for explaining it that way. :)