Help with this dosage question, how much to add

[premie_nurse]

Part 1: A 20 kg 4 year old with seizures has an order for a versed drip at 0.1 mg/kg/hr. You go to the pyxis and remove a 10 ml vial of versed that has a concentration of 5 mg/mL. Your final concentration will be 1 mg/ml after dilution with NS. How much NS will you add to the 10 ml vial of versed to obtain a final concentration of 1 mg/ml?

I figured out that the child will be getting 2 mg/hr, but I am stuck at how much NS to add to the vial. Help please!

Part 2: What till be the rate of infusion (ml/hr) for your versed gtt if it is infusing at 0.1 mg/kg/hr?

[NotReady4PrimeTime, RN]

You can't add any fluid to the vial, but you can mix the contents of the vial with fluid in a syringe or minibag.

Let's look at the problem. You have a 10 mL vial with a concentration of 5 mg per mL. 10 x 5 = ? Your vial holds 50 mg, correct?? The rest is basic Grave 5 math. You need a final volume of 50 mL to give you a final concentration of 1 mg/mL. 10 mL of Versed + x mL of NS = 50.

Part 2: 20 kg x 0.1 mg/hr = 2 mg/hr. Your final conentration is 1 mg/mL. Your rate is ?

[premie_nurse]

Thank you so much! I had that calculation that what I was given would = 50 mg. For some reason I was unable to put it all together to make the 1:1 dilution, but it all makes perfect sense now. So i would need to add 40 mL of NS to the 10 mL to = 50 mL total, right? (40mL being the answer)

And it would run at 2 ml/hr. :)

[NotReady4PrimeTime, RN]

Yes, exactly. That's a really straightforward calculation. In my world we run Versed infusions as mcg/kg/min. Using your numbers, my patient would be receiving 1.67 mcg/kg/min. I won't confuse you by giving you our equation, but you won't go wrong byfirst figuring out what you need, then dividing it by what you have.