D5 0.225% saline question

I have a handout on different IV solutions that says D5.02NS is isotonic. The tonicity is listed at 320 m Osm/L. :)

If isotonic is 280-310 mOsmol/L, and D5 !/4 NS is 321 mOsmol/L , how can it be isotonic??

Here is what I found:

Types of Hypotonic IV Solutions:

D5W (isotonic in bag, hypotonic in body d/t rapid metabolism of dextrose), 0.45% NS and 0.225 NS

Maintenance fluids: D5 ½ NS & D5 ¼ NS (hypertonic in bag, hypotonic effect in body providing water to cells; & D5NS (hypertonic in bag - less free water and more extracellular water than D5 ½ NS or D5 ¼ NS

I know in critical care we consider it hypotonic. We worry about Neuro patients getting too much of it. Brain cells can't handle too much hydration, especially when your fluid/electrolyte and compensation systems are screwed up by a head injury to begin with.

Dave

If isotonic is 280-310 mOsmol/L, and D5 !/4 NS is 321 mOsmol/L , how can it be isotonic??

Here is what I found:

Types of Hypotonic IV Solutions:

D5W (isotonic in bag, hypotonic in body d/t rapid metabolism of dextrose), 0.45% NS and 0.225 NS

Maintenance fluids: D5 ½ NS & D5 ¼ NS (hypertonic in bag, hypotonic effect in body providing water to cells; & D5NS (hypertonic in bag - less free water and more extracellular water than D5 ½ NS or D5 ¼ NS

I know in critical care we consider it hypotonic. We worry about Neuro patients getting too much of it. Brain cells can't handle too much hydration, especially when your fluid/electrolyte and compensation systems are screwed up by a head injury to begin with.

Dave

Since the D5W is quickly used up, it is hypotonic in the body, as 1/4 NS has a osmolarity of 77 mOsmol/L .

The point is that different sources quote different norms (which is why the poster was asking for help). For example, I found a reference that says isotonic solutions are 240-340 m Osm, which is arrived at by adding or subtracting 50 from the average serum osmolality of 290 mOsm. Therefore, according to this definition, D 5% and 1/4 NS is isotonic. Here are two sites that take this stand:

http://www.nursewise.com/courses/IV_hour.htm

http://www.ecc.cc.mo.us/ecc/library/web/reserves/iv_therapy.htm

And Mosby's Pocket Guide to IV Therapy (Third edition) by Larocca and Otto (1997) lists D5% and 1/4 NS as isotonic as well (page 121).Go figure.

This is no different than reading normal ranges for blood glucose. Some books say 60-110 mg/dL, while others say 70-120 mg/dl. etc. It depends on the reference book, I suppose. I didn't mean to imply my answer was definitive...it certainly is NOT. I was just sharing ONE reference that I had (but it seemed to open up a can of worms). :uhoh21: Oh well...

I stand corrected.

The point is that different sources quote different norms (which is why the poster was asking for help). For example, I found a reference that says isotonic solutions are 240-340 m Osm, which is arrived at by adding or subtracting 50 from the average serum osmolality of 290 mOsm. Therefore, according to this definition, D 5% and 1/4 NS is isotonic. Here are two sites that take this stand:

http://www.nursewise.com/courses/IV_hour.htm

http://www.ecc.cc.mo.us/ecc/library/web/reserves/iv_therapy.htm

And Mosby's Pocket Guide to IV Therapy (Third edition) by Larocca and Otto (1997) lists D5% and 1/4 NS as isotonic as well (page 121).Go figure.

This is no different than reading normal ranges for blood glucose. Some books say 60-110 mg/dL, while others say 70-120 mg/dl. etc. It depends on the reference book, I suppose. I didn't mean to imply my answer was definitive...it certainly is NOT. I was just sharing ONE reference that I had (but it seemed to open up a can of worms). :uhoh21: Oh well...

I stand corrected.

konz2,

I wasn't trying to correct you, whiich is the reason I labeled my post "Question"! I then posted what I found. I asked the question because from the references I was looking at, it didn't UNDERSTAND how it could be isotonic.

But I also notice you post a sightly different number for D51/4 then I did. But I thought maybe it was a typo...wasn't sure. But I did research it on several sites before I asked the "question". If you don't speak on something you will never know. However, I went to Baxter's site and isotonic is the same as you posted above 240 to 340. However it also classifies D51/4NS as hypertonic. But either way, whether it is isotonic or hypertonic in the bag, would you not agree, that it is hypotonic in the body?

http://www.baxter.com/services/professional_education/iv_therapy_ce/basic_one/basictwo2.html#isotonic

I would like to thank you for allowing me to think critically by challenging what I posted, as I challenge what you posted. I can indeed see why the OP started this thread:).

I have to agree with you. Sometimes the exercise of critical thinking is its own reward. I have to look at things from a practical viewpoint. I have spent too much time working with surgeons and worrying about fluid/electrolyte balance and hydration that I don't worry about hyper/hypo anymore. I know what will help, and don't think about it. Just suggest it to the residents and remind surgeons as we are recovering the patients.

Dave

konz2,

I wasn't trying to correct you, whiich is the reason I labeled my post "Question"! I then posted what I found. I asked the question because from the references I was looking at, it didn't UNDERSTAND how it could be isotonic.

But I also notice you post a sightly different number for D51/4 then I did. But I thought maybe it was a typo...wasn't sure. But I did research it on several sites before I asked the "question". If you don't speak on something you will never know. However, I went to Baxter's site and isotonic is the same as you posted above 240 to 340. However it also classifies D51/4NS as hypertonic. But either way, whether it is isotonic or hypertonic in the bag, would you not agree, that it is hypotonic in the body?

http://www.baxter.com/services/professional_education/iv_therapy_ce/basic_one/basictwo2.html#isotonic

I would like to thank you for allowing me to think critically by challenging what I posted, as I challenge what you posted. I can indeed see why the OP started this thread:).

I have to agree with you. Sometimes the exercise of critical thinking is its own reward. I have to look at things from a practical viewpoint. I have spent too much time working with surgeons and worrying about fluid/electrolyte balance and hydration that I don't worry about hyper/hypo anymore. I know what will help, and don't think about it. Just suggest it to the residents and remind surgeons as we are recovering the patients.

Dave

Thanks Dave, your insight is much appreciated :)!

Brownms46-

No worries here. I'm up for a mental challenge. :) I shoulda known better than to post my response without a rationale (*you know nurses always have to know why we do things*).

Upon reflection, I have to agree the D5% and 1/4 is probably hypotonic in the body (and that's what matters). Thanks for the reply.

Brownms46-

No worries here. I'm up for a mental challenge. :) I shoulda known better than to post my response without a rationale (*you know nurses always have to know why we do things*).

Upon reflection, I have to agree the D5% and 1/4 is probably hypotonic in the body (and that's what matters). Thanks for the reply.

kona2 ...I cracked up LOL when I read (* you know nurses always have to know why we do things*)..:rotfl: The first thing I thought of was "inquiring minds wanta know:chuckle:

Thank you for the response, as I have learned from this thread, and from those who chose to respond!

I was lol so much I forgot to say YOU"RE WELCOME!