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Magnesium sulfate

Posted

Specializes in L&D.

Calculating doses for IVPB eg. 6gram bolus. Please help.

Jolie, BSN

Specializes in Maternal - Child Health. Has 35 years experience.

How is the medication supplied? Are you adding concentrated MgSO4 to a liter of fluid? (I sincerely hope not.) Is pharmacy supplying you with a pre-mixed solution? (I sure hope so.)

How rapidly are you going to infuse the bolus? Once it is infused, what is your maintenance rate?

Why is your patient receiving this medication? How will you monitor her condition? What safety measures will you take?

These are the questions you need to answer to complete your assignment.

maxienurse

Specializes in L&D.

Medication is supplied: 20 grams Magnesium Sulfate in 500 ml of D/W bag.

Order is 6grams (150 mls) loading dose via IV pump then 2gr/hr maintenance dose.

Pt diagnosis is severe pre-eclampsia.

Management:

1st hour q 15min BP's, Resp, continuous Pusle Ox.

then

q 1 hr BP

q 1 hr DTR's

q 1 hr respirations

q 1hr urine output

q 1 hr iv input

q 2hr PO

q 4 hr auscultations of breath sounds

q 4 hr Temp.

Mag levels as per MD orders or if resp below 12/min and /or dtr's absent.

My question is at what rate does the Bolus dose of 6 grams go in ? and over what time period ?

bagladyrn, RN

Specializes in OB.

Your order or unit policy should tell you over what time period the bolus is to be delivered. Knowing that you can then determine the rate.

ashleyisawesome, BSN, RN

Specializes in LDRP.

Our policy is usually to run the bolus over 30 mins, then the maintenance Mag at 2g/hr. It should specify the rate in the order though, and this may vary by hospital or ordering physician.

maxienurse

Specializes in L&D.

Yes, I believe that is exactly my problem (the period of time is not specified) The orders do not say over what period of time the bolus should be administered. We usually give the bolus over 20 or 30 min. My point is, we DO that, but the orders don't clarify that. So, I presume we need to ask the docs to be more specific in their orders. The other thing was, I was looking for a formula. But without the time period the formula cannot be completed, correct ?

The order usually just states "give Magnesium Loading dose 6grams (or 4 grams) and Maintenance dose 2gr/hr". We have pre-set pumps to calculate the administration with "over-ride" tabs which are locked for the 6gram dose. So I was wanting a formula for my own safety. I have forgotten the formula :)

maxienurse

Specializes in L&D.

Following up on my own question:

How do you calculate the following (what is the formula) ?

Medication is: 20 grams Magnesium Sulfate in 500 ml of D/W bag.

Order is: Give 6grams (150 mls) loading dose via IV pump over 20-30min, then give 2gr/hr maintenance dose.

Jolie, BSN

Specializes in Maternal - Child Health. Has 35 years experience.

Following up on my own question:

How do you calculate the following (what is the formula) ?

Medication is: 20 grams Magnesium Sulfate in 500 ml of D/W bag.

Order is: Give 6grams (150 mls) loading dose via IV pump over 20-30min, then give 2gr/hr maintenance dose.

maxienurse,

At the risk of sounding like a COB, it concerns me that you are unable to solve this basic 2-step math problem by the factor label method or by using proportions.

Step #1: Give 6 grams over 30 minutes.

If you have 20 grams in 500 ml of fluid, how much fluid must be infused to give 6 grams?

You have already answered 150mg (which is correct.) If you are giving 150mg over 30 minutes, what is the hourly rate of the infusion?

Step # 2: Give 2 grams per hour ongoing.

With 6 grams in 150ml of fluid, how much fluid must be infused to give 2 grams? What will the hourly rate be?

Jolie, BSN

Specializes in Maternal - Child Health. Has 35 years experience.

If you have 20 grams in 500 ml of fluid, how much fluid must be infused to give 6 grams?

You have already answered 150mg (which is correct.) If you are giving 150mg over 30 minutes, what is the hourly rate of the infusion?

Sorry, I just noticed my mistake. This should read 150ml over 30 minutes, not 150mg.

Too late to edit my previous post.