Help With Mag/Intake Question

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ok, i am stressed out! :eek:. my classmates and i have an upcoming dosage examination next week. we have learned practically every way to figure out every math problem that a nurse would possibly encounter. however, we were given a problem for magnesium which left us all stumped. i am really confused. i can calculate pitocin but not magnesium. there are just so many variables to this problem and i really dont know where to start. please help!

...the tutor told us that it is actually an intake question but not a magnesium question.

2g/hr maintenance dose of magnesium from a 40 g in 1000 ml of lr. initial bolus was 4 grams over 30 minutes. iv fluids of 100 ml/hr after bolus. how much intake will client receive in 8 hours?

What was the answer to the med math question that you came up with?

850 ml, assuming that the "iv fluids of 100 ml/hr after bolus" is the LR with mag.

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magnesium

2g/hr maintenance dose of magnesium from a 40 g in 1000 ml of lr. initial bolus was 4 grams over 30 minutes. iv fluids of 100 ml/hr after bolus. how much intake will client receive in 8 hours?

1000 ml = 25 ml/1 gram x 4= 100 ml in 30 minutes

40 g

8 hours- 30 minutes= 7.5 hours left

give 2g for every hr= 25 x 2 = 50 x 7.5 = 375 ml

100 x 7.5 hr = 750

750 + 375 + 100= 1225 ml

1225 is the answer that the instructor got. needless to say, i am still totally confused. pleas break this down bit by bit if you could.

thank you!

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magnesium

2g/hr maintenance dose of magnesium from a 40 g in 1000 ml of lr. initial bolus was 4 grams over 30 minutes. iv fluids of 100 ml/hr after bolus. how much intake will client receive in 8 hours?

1000 ml = 25 ml/1 gram x 4= 100 ml in 30 minutes

40 g

8 hours- 30 minutes= 7.5 hours left

give 2g for every hr= 25 x 2 = 50 x 7.5 = 375 ml

100 x 7.5 hr = 750

750 + 375 + 100= 1225 ml

1225 is the answer that the instructor got. needless to say, i am still totally confused. pleas break this down bit by bit if you could.

thank you!

ok...so your instructor is saying that the iv fluids at 100 ml/hr is in addition to the lr with mag. i never would have read it that way unless the question specified what kind of fluids (ns, lr, etc.) was supposed to run at 100 ml/hr, but apparently she expected that you should know that. :confused:

in any case...

100 ml in 30 minutes this is your bolus.

give 2g for every hr= 25 x 2 = 50 x 7.5 = 375 ml this is your maintenance dose of mag.

100 x 7.5 hr = 750 this is the additional iv fluids at 100 ml/hr that you were supposed know is separate from the lr with mag.

750 + 375 + 100= 1225 ml this is obviously your total.

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Ok...so your instructor is saying that the IV fluids at 100 ml/hr is in addition to the LR with mag. I never would have read it that way unless the question specified what kind of fluids (NS, LR, etc.) was supposed to run at 100 ml/hr, but apparently she expected that you should know that. :confused:

Thank You.

I am just blown that they are providing a question like this on such a critical examination!

Once Again Thank You!

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Specializes in Nurse Leader specializing in Labor & Delivery.

I agree that this was a poorly worded question and if I weren't an OB nurse who deals with this type of scenario regularly, I wouldn't have gotten it right either.

You need to break it down into two problems. How much Mag fluid will she get and how much maint. IV fluid will she get.

Mag bolus of 4 gm over 30 minutes is 100 ml. Then it's 2gm/hour for the next 7.5 hours. 2gm/hour = 50ml/hour x 7.5 hours + 100 ml from the bolus.

Okay, now that you figured that out, you add to that the 7.5 hours of the maint. IV fluid at 100ml/hour, as specified on the question. 7.5 hours because it's not started until the bolus is finished.

So, 100 + (50 x 7.5)

+ 750

Does that help at all?

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Ok...so your instructor is saying that the IV fluids at 100 ml/hr is in addition to the LR with mag. I never would have read it that way unless the question specified what kind of fluids (NS, LR, etc.) was supposed to run at 100 ml/hr, but apparently she expected that you should know that. :confused:

Thank You.

I am just blown that they are providing a question like this on such a critical examination!

Once Again Thank You!

If it makes you feel better, we all had to deal with crappy questions like this at one time or another. Hopefully the other questions were more clear.

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