need help with math problem

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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.

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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.

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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?

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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:

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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

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

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

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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.

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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.

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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?

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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.

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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.

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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.

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