Medication calculation

Question

Dr orders 15mk/kg of N/S IV bolus. Patient weighs 75.5kg. How much will the nurse administer?

Answer 1

It looks like this question is missing the concentration (info on the label) of the IV med as well as the frequency of medication administration within the doctor's order. There should be #mg/#mL or something similar for the concentration of the medication. (Or the problem might say "in 50ml there are 250mg of the medication." This would give you a fraction that you can use that look like 50mL/250mg or 250mg/50mL.) And the doctor's order should state how often this med is given during the day and possibly over what amount of time this IV med is to be administered.

There many ways to do this problem correctly, but I prefer starting with the weight. Here are what the fractions should look like before canceling the units:

75.5 kg/1 x 15mg/kg x #mL/#mg =

(Pt weight)(MD order)(Concentration of med) =

Let's say the med concentration is 500mL/25mg, then the fractions would look like:

75.5 kg/1 x 15mg/kg x 50mL/250mg =

(Pt weight) (MD order)(Concentration of med)=

Once you have created these fractions you will see that you can cancel every unit out except the "mL". (Remember that kg/kg = 1 and that is why we can cancel those units. Just like 4/4 = 1!) This assures you that you have the right answer.

Once you have canceled the units, you can do the math calculations. I like to multiply all the numbers in the numerators and get that number and put it over the number you get when you multiply all the denominators. And then divide the numerator (upper) number by the denominator (lower).

You should get: 56625/250 = 226.5 mL

This is likely not a very realistic answer since we have two missing pieces of information. But I hope it helps students to see how to solve a similar problem.