Help with fluids/electrolytes.

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I am having some trouble with fluids and electrolytes.

I understand that NSS with any dextrose is hypertonic and contraindicated for those NPO or at risk for dehydration.

I am confused about others like LR and D5W.

Hypertonic, hypertonic, isotonic and what they are used for.

Does anyone know a good online study tool that may help?

I found one for ABG's, but I'm having trouble with electrolytes.

dextrose is metabolized so technically NS with anything added is hypertonic, the fact that dextrose gets metabolized really makes it an isotonic solution in the body.

NS with anything added isn't alway hypertonic.

If you have 0.9 NaCl (aka NS) with D5W then you have an isotonic fluid because as you said the dextrose is metabolized and the 0.9% NaCl is isotonic to blood/plasma.

D5 1/2 NS is HYPOtonic.

Whyyy? Because dextrose is metabolized and what's left is 1/2 NS which is hypotonic.

This is great for NPO pts as it pushes fluids into the cells and gives the cells energy (dextrose).

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Specializes in General Surgery.
dextrose is metabolized so technically NS with anything added is hypertonic, the fact that dextrose gets metabolized really makes it an isotonic solution in the body.

Normal Saline refers to 0.9 NaCl.

Keeping this in mind, NS with anything added is not hypertonic.

For example:

D5W with 1/2 NS (aka .45NS) would be Hypotonic.

The dextrose is metabolized, leaving the 1/2 NS - 1/2 NS is hypotonic.

This fluid option is great for NPO patients because you give them some energy in the form of D5 AND...

You PUSH water INTO the cells (the hypotonic 1/2 NS).

D5 + NS will turn ISOtonic because the dextrose is metabolized and the remaining NS (0.9 NaCl) is naturally isotonic.

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Specializes in General Surgery.
From what our professor said, this is okay for short term for NPO patients, especially in post op patients.

If given long term, it could actually cause fluid volume deficit.

Yes, this fluid option cannot be given long term. The cells will swell and the intravascular space will be depleted. This can also mess with their sodium levels.

So usually, patients that must remain NPO for a while post-op are started on TPN. They'll get a PICC line for it. Remember you can only give TPN through a PICC line and nothing else. :yes:

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Specializes in Pedi.
Yes, this fluid option cannot be given long term. The cells will swell and the intravascular space will be depleted. This can also mess with their sodium levels.

So usually, patients that must remain NPO for a while post-op are started on TPN. They'll get a PICC line for it. Remember you can only give TPN through a PICC line and nothing else. :yes:

You can give TPN through any kind of central access, not just a PICC line. Kids on long term TPN (i.e. short gut kids) almost always have broviacs. Kids pull PICCs out way too often for them to be relied upon for long term use.

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Specializes in med-tele/ER.
NS with anything added isn't alway hypertonic.

If you have 0.9 NaCl (aka NS) with D5W then you have an isotonic fluid because as you said the dextrose is metabolized and the 0.9% NaCl is isotonic to blood/plasma.

D5 1/2 NS is HYPOtonic.

Whyyy? Because dextrose is metabolized and what's left is 1/2 NS which is hypotonic.

This is great for NPO pts as it pushes fluids into the cells and gives the cells energy (dextrose).

Normal Saline refers to 0.9 NaCl.

Keeping this in mind, NS with anything added is not hypertonic.

Any normal saline solution with an added ingredient makes it hypertonic. I said technically because of the way it works in the body but that does not change the osmolarity and osmolality of any given solution.

And as I wrote "dextrose gets metabolized really makes it an isotonic solution in the body.", I don't get what makes what I wrote wrong.

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