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Discussion

Need help w/ another math problem!

:banghead:Thanks in advance for help! I haven't had to do this for a while now, and have returned to RN bridge program, and cannot figure this out!

Order: ampicillin 250mg IV every 4 hours for infection

Supply: ampicillin 1g vial

Nursing drug reference: Reconstitute with 10ml of 0.9% NS and further dilute in 50ml NS. Infuse over 15minutes.

How many ml will you draw fromthe vial after reconstitution?

Calculate the ml/hr to set the IV pump.

Calculate the drops per minute with a drop factor of 10gtt/ml.

COMPLETELY CLUELESS ON THIS!

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:banghead:Thanks in advance for help! I haven't had to do this for a while now, and have returned to RN bridge program, and cannot figure this out!

Order: ampicillin 250mg IV every 4 hours for infection

Supply: ampicillin 1g vial

Nursing drug reference: Reconstitute with 10ml of 0.9% NS and further dilute in 50ml NS. Infuse over 15minutes.

How many ml will you draw fromthe vial after reconstitution?

Calculate the ml/hr to set the IV pump.

Calculate the drops per minute with a drop factor of 10gtt/ml.

COMPLETELY CLUELESS ON THIS!

So 1gm =60ml.therefore 250mg=15ml.Infuse over 15 minutes = 1ml per minute.therefore 10gtt per minute.

Anyone else got a different answer as I don't use pumps.

  • Experts

order: ampicillin 250mg iv every 4 hours for infection

supply: ampicillin 1g vial

nursing drug reference: reconstitute with 10ml of 0.9% ns and further dilute in 50ml ns. infuse over 15minutes.

how many ml will you draw from the vial after reconstitution?

250 mg
(dose desired)
x 1 gram
(dose on hand)
x 1 gram/1,000 mg
(conversion factor)
x 10 ml
(amount the dose on hand comes in)
=
2.5 ml
(amount you draw from the vial after reconstitution)

calculate the ml/hr to set the iv pump.

well, if you want to get technical, you will have 50 ml + 2.5 ml = 52.5 ml total to give. remember that 60 minutes = 1 hour. so,

52.5 ml/15 minutes = x ml/60 minutes

cross multiply to get the equation
15x = 3,150

divide both sides of the equation by 15.

x = 210

the pump should be set at 210 ml/hour. if the 2.5 ml is not included in the total volume, the answer would be 200 ml/hour.

calculate the drops per minute with a drop factor of 10gtt/ml.

50 ml/15 minutes
(amount to give)
x 10 gtts/ ml
(drop factor) =
33.33 gtts/minute
, rounded to
33 gtts/minute

or,

52.5 ml/15 minutes
(amount to give) x
10 gtts/ ml
(drop factor) =
35 gtts/minute

it was very interesting that when i included the 2.5 ml when doing the iv rate calculations how the problems worked out without needing rounding off.

order: ampicillin 250mg iv every 4 hours for infection

supply: ampicillin 1g vial

nursing drug reference: reconstitute with 10ml of 0.9% ns and further dilute in 50ml ns. infuse over 15minutes.

how many ml will you draw from the vial after reconstitution?

250 mg
(dose desired)
x 1 gram
(dose on hand)
x 1 gram/1,000 mg
(conversion factor)
x 10 ml
(amount the dose on hand comes in)
=
2.5 ml
(amount you draw from the vial after reconstitution)

calculate the ml/hr to set the iv pump.

well, if you want to get technical, you will have 50 ml + 2.5 ml = 52.5 ml total to give. remember that 60 minutes = 1 hour. so,
52.5 ml/15 minutes = x ml/60 minutes

cross multiply to get the equation
15x = 3,150

divide both sides of the equation by 15.

x = 210

the pump should be set at 210 ml/hour. if the 2.5 ml is not included in the total volume, the answer would be 200 ml/hour.

calculate the drops per minute with a drop factor of 10gtt/ml.

50 ml/15 minutes
(amount to give)
x 10 gtts/ ml
(drop factor) =
33.33 gtts/minute
, rounded to
33 gtts/minute

or,

52.5 ml/15 minutes
(amount to give) x
10 gtts/ ml
(drop factor) =
35 gtts/minute

it was very interesting that when i included the 2.5 ml when doing the iv rate calculations how the problems worked out without needing rounding off.

boy did i get that one wrong!!:no::no:

  • Author

OMG! You are amazing Daytonite! I have always had this horrible mental block when it comes to problems like this, even word problems in high school algebra! I recently purchased the Dosages Made Incredibly Easy book, but not too crazy about it. Are there any books that you recommend? I need a book that specifically shows examples like you just did. I think my problem is that I don't have a clue how to set up the problem, so when you did that one, now I can do the rest of the page that I am working on!!!

Thanks!

sorry, brain fart. I am confused...its says to add 10mL of 0.9% NS to reconstitute..and further dilute w/50mL NS. So are they saying that you need to add a total of 60mL's??

They aren't saying to take that 10mL and then add it into a bag of 50mL of NS. I am reading it this way (like Nightmare is)

a total of 60mL to reconstitue making 1,000mg/60mL

15mL drawn up to get the ordered 250mg

and the gtts/min would be 10.

  • Experts
sorry, brain fart. i am confused...its says to add 10ml of 0.9% ns to reconstitute..and further dilute w/50ml ns. so are they saying that you need to add a total of 60ml's??

they aren't saying to take that 10ml and then add it into a bag of 50ml of ns. i am reading it this way (like nightmare is)

a total of 60ml to reconstitue making 1,000mg/60ml

15ml drawn up to get the ordered 250mg

and the gtts/min would be 10.

order: ampicillin 250mg iv every 4 hours for infection

supply: ampicillin 1g vial

nursing drug reference: reconstitute with 10ml of 0.9% ns and further dilute in 50ml ns. infuse over 15minutes.

the pharmacy is sending you a vial of ampicillin that contains 1 gram in powder form. you must add 10 ml of ns to this powder in order to reconstitute it to a liquid state. at that point you will have 1 gram of ampicillin in 10 ml. you need 250 mg because that is what has been ordered. that will be 2.5 ml of that solution that was just reconstituted.

that 2.5 ml of ampicillin injection is now to be added to a 50 ml piggyback bag of ns and infused intravenously into the patient over a 15 minute period. that rate will be 200 or 210 ml/hour if you are using a pump or 33 or 35 drops/minute if you are using gravity drip and regulating the infusion.

does that clear your confusion? this is a very common clinical scenario. guess you have to see it in action to understand the reality of this better.

well now that I know that they wanted that 10mL's piggy'd into 50mL I get it.

I've reconstitued hundreds of vials/bottles of meds while working in the pharmacy. I was just reading it that they wanted 2 different types of solvent mixed into the powder to reconstitute it.

(my totaly brain fart can be d/t working 80 hrs a week for the past 6 wks...ugghh..) But don't worry, I would have asked another before reconstituting anything I wasn't 100% sure of, that AND call the pharmacy :)

I would have missed this question (thought the same way CT and NM did), and if it happened to be on my 3rd attempt, I'd be out of nursing school, and angry.:cry:

Thank God for this forum, and it's posters. What a great resource.

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