d5 1/2 NS

[jok200]

I have been reading in multiple places that D5 1/2 NS is a isotonic fluid and is used as a maintenance fluid??? How is this possible when it is a hypertonic solution, wouldn't that make the patient dehydrated?? I spent a while looking this up and found quite a bit of conflicting information which is why I am asking the experts.


thank again-

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[urge]

Maintenance is around 0.22%. The 0.45% has more sodium but I doubt it is a big deal in pts with normal kidneys.

I don't think you could consider someone hydrated or not based on their sodium concentration. Have you read an IM chapter on volume and Na concentration? Maybe you should.

If I give you 4L of 0.9% you would be pretty hydrated.

 

[BADMD]

Sugar is not static.

D5 @ 150 ml/ hr is about 25 calories an hour.

 

[jok200]

I didn't understand either one of you... maintenance is around 0.22% ??? what does that mean??? Okay so is d5 1/2 NS isotonic or hypertonic? Seems like what your trying to say is that it doesn't matter and is negligible, is that correct? Sugar is not static, what does that mean?? And why does it matter that D5 @ 150ml/hr is about 25 calories??

 

[dhb]

Water is not compressible

 

[DrBeaker]

I didn't understand either one of you... maintenance is around 0.22% ??? what does that mean??? Okay so is d5 1/2 NS isotonic or hypertonic? Seems like what your trying to say is that it doesn't matter and is negligible, is that correct? Sugar is not static, what does that mean?? And why does it matter that D5 @ 150ml/hr is about 25 calories??

What he means is the dextrose in the IVF doesn't stay intravascular. It crosses from the plasma to cells in the body. As far as tonicity, how many meq of sodium and chloride in 0.9NS? 154 meq of each for a total of 308. 0.45NS has 77 of each for a total of 154meq. I remember 300meq for a normal blood osmolality. Technically NS is hypertonic and 1/2NS is hypotonic. The dextrose is used by the body for food.

 

[jok200]

thank you Dr. Beaker

 

[HollywdAnesth]

What is "normal" about normal saline?

 

[Idiopathic]

What is "normal" about normal saline?

when named, it was considered the safest, most "normal" physiologic replacement, it doesnt speak to the chemical normality of the solution.

 

[Idiopathic]

What he means is the dextrose in the IVF doesn't stay intravascular. It crosses from the plasma to cells in the body. As far as tonicity, how many meq of sodium and chloride in 0.9NS? 154 meq of each for a total of 308. 0.45NS has 77 of each for a total of 154meq. I remember 300meq for a normal blood osmolality. Technically NS is hypertonic and 1/2NS is hypotonic. The dextrose is used by the body for food.

D51/2NS is hypertonic in solution until the glucose is metabolized, i dont think anyone considers it clinically hypertonic really though. in actuality it is hypotonic, and the primary use of 1/2NS as replacement fluid is to replace extravascular/intracellular losses, as the hypotonic infusate will move to relatively hypertonic areas like dehydrated tissue and cells.

 

[dhb]

I have been reading in multiple places that D5 1/2 NS is a isotonic fluid and is used as a maintenance fluid??? How is this possible when it is a hypertonic solution, wouldn't that make the patient dehydrated?? I spent a while looking this up and found quite a bit of conflicting information which is why I am asking the experts.


thank again-

D5 1/2NS is chemically hypertonic but clinically hypotonic since glucose distributes to the whole body and is transformed or metabolized so you are giving some amount of free water.
A hypertonic solution doesn't always cause dehydration because the kidneys can excrete osmotic loads.