Calculation about dilution

Khoo Sereen said:

I'm confused as my lecturer told us if 10mg/1ml IV morphine we need to dilute with 9ml of NS to make it total 10ml. If I calculate the question with this concept, I will have 11ml after dilution as 10ml NS added with 1ml morphine.

What does 9ml of NS+1ml of morphine=?ml

Khoo Sereen said:

Total volume will be 10ml, is there any mistakes?

No. I'm just trying to figure out where you came up with 11ml.

Khoo Sereen said:

oh~it comes from 10ml of NS+1ml of morphine

But your instructor told you to dilute it in 9ml of NS.

sallyrnrrt said:

I generally don't do home work

You have on hand10mg/1ml. Morphine, you need to give( not serve) 2mg. Morphine diluted in saline flush

Each 1ml of 10 mg morphine, contains 1mg of morphine per 0.1ml...... There fore to give 2mg, you would add to the flush

0.2ml of the stock 10mg / 1 ml of morphine......

If you added 1ml of your stock solution to even 100mls. normal saline, regardless of the dilution, you would be giving 10mg morphine, instead of 2 mg.......

The way I was taught was to pull the entire 1ml of MS and dilute it in 9ml of NS which would have resulted in a 1mg/1ml concentration. Then to administer 2mg I would give 2cc. My practice has always been to dilute meds that way. Now most of my practice has been peds so that may be why. I'm not sure the OP is grasping the point of the exercise.

MunoRN said:

It's actually a very legitimate question, since based on the question you would be ending up with a final volume of 11mls. This is often how the question is phrased in nursing school: "dilute with 10ml NS", which is different than "dilute with NS to produce 10mg/10ml". Leaving aside that seems to be perpetuating the myth that these medications need to be diluted at all, the correct answer to the question as written would be that you would have a concentration of 10mg/11ml, and to give 2mg you would give 2.2 ml, which if course is silly and why the more correct answer is that the instructor who wrote this question is not to bright.

What's confusing me is first he said the instructor said to dilute it in 10 mls then it was 9 so I'm not sure what the original question was. As for diluting, in peds/neo we do have to dilute so we get accurate and measurable amounts. Not so much with adults.