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need help with math problem

Hello,

I have a question about a math question that we just had. the question is....

your client presents in the clinic complaining of fluttering in her chest. she is placed on a cardiac monitor which shows a new onset atrial fibrillation. she has history of COPD and CHF. home medications are digoxin and lasix everyday.

vitals: HR 110-120, RR 22, B/P 100/60

weight: 100 Kg.

she is admitted to the inpatient monitored unit and started on a Cardizem drip. the pharmacy sends you a 50mL bag of 0.25 NS with 250 mg of cardizem added. your order states to start the infusion at 0.5 mg/kg/min.

using nursing judement, would you hang this infusion? why?

my question is...wouldn't you need to check the patients digoxin level before giving this medication? I know that Cardizem will lower the patients BP even lower and can also increase digoxin serum levels.

Daytonite, BSN, RN

Specializes in med/surg, telemetry, IV therapy, mgmt.

you are probably right. however, this drug would be given iv in an emergency situation in an attempt to get an arrhythmia, atrial fibrillation, under control and only for a short term. if it is unsuccessful, cardioversion would be done. cardizem (diltiazem) is used to control the rapid ventricular rate in atrial fibrillation by slowing electrical conduction through the sa node. however, it can increase the serum concentration of digoxin.

the dilution information given does not sound right to me. 250 mg vials of cardizem (diltiazem) come in 50 ml vials and are then mixed in larger volume iv fluids. based on the figures you were given the cardizem (diltiazem) would need to infuse at 600 ml/hour (50mg/minute) and that is way too much drug. maximum safe iv infusion dose should not exceed 15mg/hour.

Thank you so much for the help. That's the other thing that bothered me about this problem, should there be a safe dose range to go by?

Daytonight,

can I just say that "YOU'RE AWESOME"!

I've been on this site for about 6 months now and I've passed through many of your posts and replies to others. You seem to have so much knowledge and inspire me to be just that knowledgable and educated in nursing!:bow:

UM Review RN, ASN, RN

Specializes in Utilization Management.

Thank you so much for the help. That's the other thing that bothered me about this problem, should there be a safe dose range to go by?

Yes, there is. But of course, that depends on the patient.

From Medscape (WebMD). Here's a link. (It's a great idea to register with this site, you'll find it a valuable resource):

http://www.medscape.com/druginfo/monograph?cid=med&drugid=5214&drugname=Cardizem+IV&monotype=monograph&secid=3

hypocaffeinemia, BSN, RN

Specializes in Critical Care.

Thank you so much for the help. That's the other thing that bothered me about this problem, should there be a safe dose range to go by?

Source: Thomson Micromedex

Start at 5-10 mg/hour, increase in 5 mg increments up to *NO MORE THAN* 15 mg/hour up to 24 hours.

---

In practice at my facility I've (rarely) seen it up to 20 mg / hour for short durations on larger patients.

Note that this is discounting boluses often given before the drip is started.

UM Review RN, ASN, RN

Specializes in Utilization Management.

When I bring up the link it is blank and I am a registered user of the website.

Oh crud. Let's see if this one works.

http://www.medscape.com/nurses

In the top search field, there's a tab for "drug" search. Type in Diltiazem IV

http://search.medscape.com/drug-reference-search?newSearch=1&queryText=diltiazem+IV

That should get you there. It's such a great resource, it's worth it to register and get the newsletters, updates and CMEs.

I didn't put this in the math problem, but on the first question it ask...your order states to start the infusion (Cardizem) at 0.5mg/kg/min. Which is way too much medication to start out with because the recommended doseage shouldn't exceed 15mg/hr.

then the next question had ask.....if the MD order stated to start the infusion at 5/mg/hr. at what rate would this be?

5mg/Hr x 50mL = 1 mL/hr

250mg

is this correct? and if so, they way the question is written with 5/mg/hr, does that mean it should be increased each time (5mg/hr) not to exceed 15mg/hr?

hypocaffeinemia, BSN, RN

Specializes in Critical Care.

I didn't put this in the math problem, but on the first question it ask...your order states to start the infusion (Cardizem) at 0.5mg/kg/min. Which is way too much medication to start out with because the recommended doseage shouldn't exceed 15mg/hr.

then the next question had ask.....if the MD order stated to start the infusion at 5/mg/hr. at what rate would this be?

5mg/Hr x 50mL = 1 mL/hr

250mg

is this correct? and if so, they way the question is written with 5/mg/hr, does that mean it should be increased each time (5mg/hr) not to exceed 15mg/hr?

250 mg in 50 mL is a dangerously unsafe concentration-- you shouldn't hang it at all. It's concentrated for pharmacies to use one vial to make multiple admixtures off it.

Daytonite, BSN, RN

Specializes in med/surg, telemetry, IV therapy, mgmt.

i'm having difficulty understanding the question. i think it's because of the dilution instructions. it would depend on the concentration of the resulting final mixture. 2007 intravenous medications, 23rd edition, by betty l. gahart and adrienne r. nazareno lists the dilution and resulting dose and infusion rates for cardizem as follows:

  • where the final concentration after dilution is 1mg/ml (125mg cardizem to 100ml of diluent) the dose and infusion rates would be
    • 5mg/hour = 5ml/hour
    • 10mg/hour = 10ml/hour
    • 15mg/hour = 15ml/hour

    [*]where the final concentration after dilution is 0.83mg/ml (250mg cardizem to 250 ml of diluent) the dose and infusion rates would be

    • 5mg/hour = 6mg/hour
    • 10mg/hour = 12ml/hour
    • 15mg/hour = 18ml/hour

    [*]where the final concentration after dilution is 0.45mg/ml (250 mg cardizem to 500 ml of diluent) the dose and infusion rates would be

    • 5mg/hour = 11ml/hour
    • 10mg/hour = 22ml/hour
    • 15mg/hour = 33ml/hour

after re-reading your original post and thinking on this a while (i am not familiar with using this drug) it sounds like the second group of figures would be what you are looking for and the answer would be 6ml/hour.

hypocaffeinemia, BSN, RN

Specializes in Critical Care.

i'm having difficulty understanding the question. i think it's because of the dilution instructions. it would depend on the concentration of the resulting final mixture. 2007 intravenous medications, 23rd edition, by betty l. gahart and adrienne r. nazareno lists the dilution and resulting dose and infusion rates for cardizem as follows:
  • where the final concentration after dilution is 1mg/ml (125mg cardizem to 100ml of diluent) the dose and infusion rates would be
    • 5mg/hour = 5ml/hour
    • 10mg/hour = 10ml/hour
    • 15mg/hour = 15ml/hour

    [*]where the final concentration after dilution is 0.83mg/ml (250mg cardizem to 250 ml of diluent) the dose and infusion rates would be

    • 5mg/hour = 6mg/hour
    • 10mg/hour = 12ml/hour
    • 15mg/hour = 18ml/hour

    [*]where the final concentration after dilution is 0.45mg/ml (250 mg cardizem to 500 ml of diluent) the dose and infusion rates would be

    • 5mg/hour = 11ml/hour
    • 10mg/hour = 22ml/hour
    • 15mg/hour = 33ml/hour

after re-reading your original post and thinking on this a while (i am not familiar with using this drug) it sounds like the second group of figures would be what you are looking for and the answer would be 6ml/hour.

i think there are numerous typos on either the original post or in the problem given to solve. i'm fairly familiar with the drug and we typically always use a concentration of 1 mg / 1 ml to make it easy to titrate on the fly.

the question also says .25% ns, which is a clear typo on somebody's part: ns is 0.9%; a 0.25% solution would be extremely hypotonic.

I'm totally confused....our question had that the pharmacy sends you a 50mL bag of 0.25 NS with 250 mg of Cardizem added. I feel like they are trying to trick us, which is nothing unusal. What really bothers me is that we haven't been taught this, so it's really hard to know what to do with the problem. I've looked in the drug books and in our text books and they say to start the infusion at 0.25mg/kg; may repeat in 15 min with a dose of 0.35 mg/kg. may follow with continuous infusion at 10mg/hr (range 5-15mg/hr) for up to 24hrs.

I didn't understand why she put in the problem 5/mg/hr. most of the time you would see it as 5mg/hr, but this just seems different to me. could it mean that it would be increased in increments of 5 mg???

so would I take the 0.25mg/kg = 25mg divide by 250 x 50mL = 5mL/hr???

I so sorry to keep bothering you with this crazy problem, but it will drive me crazy until I either figure it out or someone can explain it to me how it should be done.

Thanks!!

Daytonite, BSN, RN

Specializes in med/surg, telemetry, IV therapy, mgmt.

My IV drug book says that the 25mg of Cardizem comes as a solution of 50mL and that it needs to be added to an IV solution and further diluted.

UM Review RN, ASN, RN

Specializes in Utilization Management.

I can only tell you how we do it.

Our Cardizem comes in a bottle of 125 mg in a 25 ml bottle. We draw that up and mix it into a 100 ml bag of either D5W or NS 0.9%.

Total = 125 ml in the bag to 125 mg of the med. The concentration is then 1mg of medicine to 1 ml of fluid.

We can run up to 20 mg (or ml, it's the same amount either way), per hour, with up to a 20 mg bolus.

Usually, we give a 10 mg bolus and then run the drip at 5-10 ml/hr.

I concur with Daytonite; the dilution is too strong and I would not hang the med.

just had another thought about this question. I don't think the order is complete. therefore, you would call the doctor to clarify the order. the order that the teacher has given us doesnt have a range to go by. Could this be correct?

this would also be true for the 2nd question two, right?

This is one of those crazy problems that causes you not to sleep at night because you lay in bed at night trying to figure the problem out!

Thanks again

UM Review RN, ASN, RN

Specializes in Utilization Management.

The question was:

using nursing judgement, would you hang this infusion? why?

Based on my experience as a nurse, I would not hang it. The dilution seems wrong to me. I would call the pharmacy and/or the doctor about this medication and get it clarified.

Daytonite, BSN, RN

Specializes in med/surg, telemetry, IV therapy, mgmt.

thanks, angie. i was going by what i was seeing in my copy of 2007 intravenous medications, 23rd edition, by betty l. gahart and adrienne r. nazareno. i am not familiar with the practical application of this drug at all. wouldn't they use the drug as an emergency stopgap, but eventually defibrillate to covert back to a sinus rhythm?

hypocaffeinemia, BSN, RN

Specializes in Critical Care.

thanks, angie. i was going by what i was seeing in my copy of 2007 intravenous medications, 23rd edition, by betty l. gahart and adrienne r. nazareno. i am not familiar with the practical application of this drug at all. wouldn't they use the drug as an emergency stopgap, but eventually defibrillate to covert back to a sinus rhythm?

depends on the patient. i've seen them use cardizem to get the rate under control for a couple days (iv continuous followed by po extended release) while anticoagulating, then proceeding with electrical or chemical cardioversion or even ablation.

other times, i've seen the cardizem kick the patient back into sr on it's own.

ok...i get the part about the dilution and not to hang the med, but what about where it says....if the md order stated to start the infusion at 5/mg/hr. at what rate would this be? does this mean that the order would be increased by 5 mg increments per hour? for example, my drug book says that the dosage starts out at 0.25mg/kg; may repeat in 15 min with a dose of 0.35mg/kg?

i'm so sorry to keep asking these questions over and over, but i really want to understand what she is asking. i understand if she had put 5mg/hr, but by her putting 5/mg/hr kind of changes the problem.

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