Student Nurse Mag question... Any help appreciated!

[StandardDeviation]

You are caring for a woman who has been admitted with PIH. An IV of LR at 125ml/hr has been started. Orders indicate the patient is to receive a 4 gram loading dose of Magnesium Sulfate (MgSO4) infused over 30 minutes. After the loading dose is given, you are to begin a 2 gram per hour infusion of MgSO4.

You have available premixed MgSO4 40 gram to 1000ml of LR and premixed MgSO4 4gram in 100ml of LR.

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I have all the math worked out. What I was wondering is I have a question stating "Which line would you set up as your main line?" I have no idea on this and I have no information leading me in any direction. I was supposing that I would set the loading mag on primary, the continuous mag on secondary, and then the lactated ringer's after loading mag is done, but that makes me nervous because I wouldn't think you would want a mag to be your primary line?

Any help is appreciated.

Thank you.

[NRSKarenRN, BSN, RN]

OB not my speciality, but as Infusion RN:

Primary IV site = hourly around the clock IV main solution ordered for patient with highest hourly amount to infuse.

Secondary sites/Piggy back = Intermittent scheduled IV's or bolus solutions

like antibiotics, antiulcer meds, pain mgmt infusions, Electrolyte loading dose/bolus:K', Mg+ riders, blood products

In this case:

Primary #1 infusion is Lactated ringers (LR at 125ml/hr)

Secondary: First give Magnesium loading dose (premixed MgSO4 4gram in 100ml of LR); upon completion setup Mg infusion (premixed MgSO4 40 gram to 1000ml of LR @ 2gm/hr) same secondary line.

This way, once Magnesium level is stable and DC'd, can continue maintenance fluid uninterrupted and just disconnect secondary setup.

[StandardDeviation]

Thank you for your reply. I did have one other question. Since the two premixed bags are the same concentration and one is just smaller than the other, why not just use the one 1000ml bag? Does that matter really? I start back next week and hope to ask all these questions, but in the meantime, it's driving me crazy!

[darcicat]

It is a patient safety thing.

1) All of your infusion rates are different - 125 ml/hr for your LR, 200/hr for your loading and 50/hr for your maintenance dose.

2) If you hang your 1000ml mag bag as a piggyback it will be higher on the pole than your primary bag, and that is how you choose what bag is infusing at what time, it works by gravity, even when you have a pump.

3) So, if you did it that way, you would hang your LR lower on the pole and set it as the primary at 125/hr. Then your 1000mls of mag higher and program 100 mls only to infuse at 200/ml an hour.

4)HOWEVER, when your secondary program was over after 100 mls, the secondary would switch off and the primary settings would take over (1000 mls at 125/hr) BUT your mag bag is still higher on the pole! So you would be infusing your mag at 125/hr not 50/hr like you were supposed to.

5) There is no way that you could prevent this from happening in that scenario, because you cannot be at the bedside every minute. You have to pee, take a break, see your other patients, etc. So you never want to set something up like that. Therefore the pharmacy will break it up into two bags. This prevents that from happening. You just have to write a note to yourself to come back in 30 minutes to switch the bags.