Dosage calculation Help!

[Calhoungirl24]

Hi! Im in my 3rd semester of my ADN program and we just started advanced dosage calculations and i came across some problems that i have no idea how to do. Here it is:

Drug A 10mg ordered. The pharmacy sends up drug A 5mg/2mL. The drug reference states to dilute to a concentration of 1mg/mL and administer at a rate of 5mg per minute.

• The total volume the nurse will administer is______mL
  
• The nurse will add____mL of dilutent to make the appropriate concentration of the drug.
  
• Over how many minutes will the medication be administered over?
  

[Apple-Core, ASN, BSN, RN]

Actually, not true. Flolan is dosed ng/kg/min.

SO my answer was right or wrong? I'm confused!

[chare]

SO my answer was right or wrong? I'm confused!

Your answer is correct, however your work does not support the answer.

[…]

I figured out everything the same as you. Then I think it is this:

* You need 0.005mcg/minute, which is delivered per. 0.025ml of DSW

* This equates to 0.3mcg/hour, meaning a person will need to receive 1.5ml of the DSW solution over the course of an hour

* The amount of solution required over the hour is 1.5ml

* I have no clue about setting pump rates - haven't done that yet, sorry

[…]

You started out with an incorrect unit of measure. You were ordered to infuse 5 mcg (0.005 mg) per minute, and you used 0.005 mcg. Then, you used the volume of 0.025 mL, that the OP provided. An infusion at 1.5 mL /hour, with the concentration (50 mg/250 mL) would deliver 300 mcg/hour. In my opinion most, if not all of the confusion arises from converting 5 mcg to 0.005 mg. I would have worked the problem quite differently.

First, since ww are solving for the hourly infusion rate, I would have determined how many mcg the patient would receive in 1 hour: (5 mcg/1 min) × (60 min/1 hour) = 300 mcg/hour.

Next, I would the calculate the concentration of the medication per mL. As you have two units of measure (mg and mcg), you need to convert one. As the infusion was ordered using mcg, I would convert the concentration to mcg as well: (50 mg/250 mL) × (1000 mcg/mg) = 200 mcg/mL.

Then, using the equation D/H × V, (where D = dose ordered [300 mcg]; H = the concetration [200 mcg]; and V the volume [1 mL] for H.), or (300 ÷ 200) × 1, or 1.5 mL/hour.

This calls attention to two of the most common errors in medication math, mismatched units and problems arising from the use and misplacing of decimal ppints. And, as Esme12 addressed in her post, the results can be catastrophic.

ETA: In practice most, if not all, premaid infusions will provide the concentration on the package.

[Apple-Core, ASN, BSN, RN]

Your answer is correct, however your work does not support the answer.

You started out with an incorrect unit of measure. You were ordered to infuse 5 mcg (0.005 mg) per minute, and you used 0.005 mcg. Then, you used the volume of 0.025 mL, that the OP provided. An infusion at 1.5 mL /hour, with the concentration (50 mg/250 mL) would deliver 300 mcg/hour. In my opinion most, if not all of the confusion arises from converting 5 mcg to 0.005 mg. I would have worked the problem quite differently.

First, since ww are solving for the hourly infusion rate, I would have determined how many mcg the patient would receive in 1 hour: (5 mcg/1 min) × (60 min/1 hour) = 300 mcg/hour.

Next, I would the calculate the concentration of the medication per mL. As you have two units of measure (mg and mcg), you need to convert one. As the infusion was ordered using mcg, I would convert the concentration to mcg as well: (50 mg/250 mL) × (1000 mcg/mg) = 200 mcg/mL.

Then, using the equation D/H × V, (where D = dose ordered [300 mcg]; H = the concetration [200 mcg]; and V the volume [1 mL] for H.), or (300 ÷ 200) × 1, or 1.5 mL/hour.

This calls attention to two of the most common errors in medication math, mismatched units and problems arising from the use and misplacing of decimal ppints. And, as Esme12 addressed in her post, the results can be catastrophic.

ETA: In practice most, if not all, premaid infusions will provide the concentration on the package.

Thank you for clarifying! Hopefully my disclaimer gets me off the hook! I see where I've gone wrong.

Which brings me to my question....other than premade meds in the correct dose needed, what checks are in place to prevent human error? Does a mix of med solution have to be approved by more than just the person mixing it? The story above about the NICU nurse is so, so sad for everyone involved.

[chare]

At my facility there us a list of designated "high alert" medications, all of which require an independent double check by another nurse. In the PICU, we require an independent double check for all infusions.

When you calculate any infusion or medication, if your answer just doesn't "feel" right, or there is ever any doubt that your work is correct, never hesitate to ask someone to check you.

[la_chica_suerte85, BSN, RN]

Thank you for clarifying! Hopefully my disclaimer gets me off the hook! I see where I've gone wrong.

Which brings me to my question....other than premade meds in the correct dose needed, what checks are in place to prevent human error? Does a mix of med solution have to be approved by more than just the person mixing it? The story above about the NICU nurse is so, so sad for everyone involved.

Also, be forewarned that sometimes, even though pharmacy verifies the order, we verify the order, everything squares with the drug references but what you get sent from pharmacy ends up being completely wrong. There was someone here who recently posted about having to give what they knew in their gut was the completely wrong amount of insulin. The label and concentration did not match what they clearly had as the wrong amount in milliliters (it was an unreasonably large amount for that unit dose of insulin). The nurse was still precepting and her preceptor didn't back her up, pharmacy swore they sent the right insulin amount so the nurse, using very sage clinical judgment, checked to see if there was enough glucagon or dextrose on the unit in case the patient's blood glucose tanked, gave the insulin, monitored the patient and intervened when the blood glucose did indeed drop to an unsafe level.

But, that didn't have to happen. You can always check with a nurse who maybe had that patient prior and say, "Hey, for patient so-and-so, their BG was such-and-such and pharmacy sent this. Does this seem right to you?" Often times, that nurse will confirm your suspicions. If there is no nurse available for this confirmation, you can check with the charge nurse. If you really feel in your heart of hearts that something is off about a med, just send it back to pharmacy. Especially with IV meds, we're responsible for looking at it and making sure it doesn't look funky (i.e. cloudy, unusual color, crystallization -- ahem, mannitol, or any sediment or other characteristic that should not be there) prior to administering it. They'll remake it and send it back. At least where I work, that is the case. If I don't like it and I can't get pharmacy to be responsive then I go, "Here, YOU look at it." And, voila, once someone there has eyes on it, someone frequently will realize it is wrong and the issue will be corrected.

[Steffy44]

I always used ratio proportion to find my answers. Usually more steps but it worked for me. Others used the more chemistry looking method and it worked for me. Just take it in pieces and you'll be fine.