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Discussion

Math question I can't find the answer to!

I have a math test coming up and I have some questions on the study guide we were given. I have been looking in my Math for Meds book for more help but can't find what I'm specifically looking for. I hope someone can help me out with these, there's only 1 example for some of these things, and it takes me a lot of practice to get comfortable with new calculations and formulas.

Fentanyl:

25 (??) x dose mcg/kg/hr x weight kg = C (concentration?) (mcg/25mL)

rate mL/hr

Is the 25 standard? Even in the order example given, the Fentanyl dose is in 25mL. Or is it a dilution concentration of Fentanyl per 25ml? Everything else I get where to plug in info to get the correct calcuation.

Insulin:

units/kg/hr x weight (kg) x volume to prepare (mL) = units of insulin to dilute in 20mL volume

rate of infusion (mL/hr)

There's a simplified version of the formula which is 4 x kg = units of insulin to dilute in 20mL volume. So let's say my baby is 0.9kg:

4 x 0.9kg = 3.6 units of insulin to dilute in 20mL volume.

Then there's a list to titrate the dose, like 0.02 unit/kg/hr = 0.1mL/hr etc. So what do I do with that? I'm so confused and there is no example to work with. Where do I plug that in when I already have my units to dilute? I don't know where to go from here.

Thanks! :nurse:

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    "I don't know where to go from here."

    Try the library.

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    What u have posted is very confusing. As far as I know the formula for babies/paeds or adults who don't weight much (elderly/anorexics for example) are calculated thus:

    mcg/per kilogram/per hour. Thus it's dose/weight/hour. This will then give u the mls per hour. If the doctor's order says 'give over 8 hours' for example, then u divide again by 8 hours and that gives u the final mls/hour.

    I don't know what the list is ur referring to.

    I am not a paeds nurse - far from it - but this is the calculation we use down in Oz. And it hasn't changed as far as I'm aware.

    It sounds like ur trying to interchange too many calculations into one order. What does ur calculation actually say? Look at it carefully then decide what calc formula you have to use.

    If you give IV you have to follow your facilities IV drug book as to how to reconstitute the drug.

    Sorry I can't be more help.

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    • Author

    I know it's confusing! It's straight out of our study guide. I almost wonder if I'm missing a page somewhere. I've been trying to contact the education department because I'm totally stumped with the insulin equation. :confused:

    Thanks anyway.

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    I don't understand the complicated insuling formula. I do understand how to calculate the latter.

    I've never seen anything like the Fentanyl.

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    no clue on the fentanyl, looks like something might be missing there, and overly complicated on the insulin. ask the pharm faculty what the heck this all means, ask for a typical patient situation and physician order as an example, and see if it makes sense.

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    • Author
    ask the pharm faculty what the heck this all means, ask for a typical patient situation and physician order as an example, and see if it makes sense.

    i know! how do they hand out a study guide with just these formulas?? no examples for some of them, no practice problems... :confused: :uhoh3:

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