Please help w inotropic calculations

  1. Hi,

    Any help is greatly appreciated. I was in a pull-out to a CHF clinic today, which was so great by the way, and part of my assignment is to calculate the dosage for two different pts. One on Primacor and one on Dobutamine. Unfortunately, the two nurses were so used to using a calculator called a "Dosage Calculator" specially designed for nurses, that they were unable to show me how to do the problem by hand, and it's due tomorrow! Just a little freaked right now. Thank you so much for any help you can give. Write me if I left something out. I'll be monitoring for responses all night.

    Pt is 51 kg. Primacor 0.375 mcg / kg / min

    Pt is 97 kg. Dobutamine 2.5 mcg / kg / min
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    About Bumashes, MSN, RN, APRN, NP

    Joined: Mar '06; Posts: 500; Likes: 569


  3. by   jamonit
    these are parenteral, yes? if so, you will need to know the quantity (available in IV bag--what it was hung with, like 250 ml of NS)

    the equation usually looks like this:
    D (desired amt in mcg or mg)/time (min or hour)/ H (have available in IV bag x(times) Q (quantity in IV bag)=x
    x=ml/min or ml/h

    for instance, run dobutamine 500 mg in 250 ml d5w at 5 mcg/kg/hr. the patient weighs 69.1 kg. The pump would be set at ____ ml/hr.
  4. by   Bumashes
    Yes, it is parenteral. Okay. Let me try to solve it. Sorry, but I'm running on 2 hours of sleep and my calculator is lost. Would it be 20ml/hr? Or 14ml/hr? Don't know if I'm dividing or multiplying here. We haven't gotten into this kind of dosage cal yet. In fact, we're scheduled to learn it this Thursday. That will be just a little too late, though.
    Any clue what a normal quantity is for Primacor and what it is hung with?
  5. by   AnnieOaklyRN
    With the information you can figure out the mcg/min dose, but not the mL per hour or minute because we do not know the concentration.

  6. by   Bumashes
    Really that's all I need, but additional info is always helpful.
  7. by   Daytonite
    pt is 51 kg. primacor 0.375 mcg / kg / min
    the usual dilution of primacor is 200mcg/ml in pre-filled bags. also, keep in mind that the dose desired here is a complex fraction (0.375 mcg/1 kg/ 1 minute) so we have to do some mathematical manipulation in working out the problem properly. by dimensional analysis you want to end up with ml/hour (to program into the iv pump).
    0.375 mcg/1kg (dose desired) x 1/1 minute (reciprocal fraction of denominator in dose desired--i am doing this to clear it out of the denominator) x 95 kg (patient's weight) x 1 ml/200 mcg (dose on hand--mixture of primacor on hand) x 60 minutes/1 hour (conversion factor) = 10.91 ml/hour which rounds off to 11ml/hour which is what you would set the iv pump to.
    pt is 97 kg. dobutamine 2.5 mcg / kg / min
    dobutamine can be mixed in a different concentration depending on what the nurses generally like to use. all i can do is compute to mcg/minute for this patient. to determine the rate of infusion, you need to know what the dilution of the iv mixture of the dobutamine is and apply it to the mcg/min answer i have given you applying a conversion factor, as i did above, to covert from ml/minutes to ml/hours for setting the iv pump.
    2.5 mcg/1kg (dose desired) x 1/1 minute (reciprocal fraction of denominator in dose desired--i am doing this to clear it out of the denominator) x 97 kg/1 (patient's weight) = 242.5 mcg/1 minute (delivery rate)
  8. by   Bumashes
    Thank you ever so very much. Lifesaver!