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Old 04-03-2011
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Question When should we give 5% dextrose in water?

When should we give 5% dextrose in water rather than normal saline for instance?
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Old 04-03-2011
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Good question. I consulted UpToDate and the answer actually makes a lot of sense.

"Dextrose-containing solutions should be used in patients with hypoglycemia or alcohol or fasting ketoacidosis, and should be given with insulin in patients with hyperkalemia and no hyperglycemia since insulin-mediated entry of potassium into cells will lower the serum potassium concentration.

Dextrose-containing solutions should not be used in patients with uncontrolled diabetes mellitus or hypokalemia. With respect to hypokalemia, the administration of dextrose stimulates the release of insulin, which promotes potassium entry into cells with possible worsening of the hypokalemia."
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Is there a difference between 5% dextrose in water and 5% dextrose in normal saline? If so, when should we transfuse each?
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Old 04-04-2011
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Default good one :)

ok, so, for this I believe you need to know these values, more or less by heart:
Concentration of Na in common infusate:
1. Na in 0.45% Nacl = 77mmol/L & 1 L= 500ml of free water
2. Na in 0.9% Nacl = 154
3. Na in 3% Nacl = 513
4. Na in 5% Nacl = 855
5. Na in Ringers Lactate = 130
6. Na in D5W = 0 & 1L = 1 L of free water

Once you do your deficit calculations for Na, or water, then you use the crystalloid most appropriate.
One of the key concepts you need to know is the following:
When you give Dextrose containing fluid you increase insulin release. This can be real bad in some situations such as Hypokalemia, if you give dextrose containing fluid--> increase inslulin--> decrease K even more---> BIG OOOPS,
on the other hand D5W is good for situations like Hypervolemic hypernatremia to remove the excess Na.
At the end it comes down to which has what and what and how much you need to correct. Know the formulas too.
Hope this was helpful
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Old 04-04-2011
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That's useful.

Thanks for sharing.
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Old 04-04-2011
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Quote:
Originally Posted by Medtobe View Post
ok, so, for this I believe you need to know these values, more or less by heart:
Concentration of Na in common infusate:
1. Na in 0.45% Nacl = 77mmol/L & 1 L= 500ml of free water
2. Na in 0.9% Nacl = 154
3. Na in 3% Nacl = 513
4. Na in 5% Nacl = 855
5. Na in Ringers Lactate = 130
6. Na in D5W = 0 & 1L = 1 L of free water

Once you do your deficit calculations for Na, or water, then you use the crystalloid most appropriate.
One of the key concepts you need to know is the following:
When you give Dextrose containing fluid you increase insulin release. This can be real bad in some situations such as Hypokalemia, if you give dextrose containing fluid--> increase inslulin--> decrease K even more---> BIG OOOPS,
on the other hand D5W is good for situations like Hypervolemic hypernatremia to remove the excess Na.
At the end it comes down to which has what and what and how much you need to correct. Know the formulas too.
Hope this was helpful
Thanks Medtobe!

Could you explain how D5W removes the excess Na?

Also, in #1, what do you mean by "1 L = 500 ml of free water"?
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Old 04-04-2011
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Default oh, my bad

I am glad, it helps.
Ok, to answer your questions, really both questions fall in to same response:
Free Water= Water deficit
When you use the formula for water deficit= [TBW x serum Na-140] / 140
and again TBW= 0.6 x wt(kg) for men & 0.5 x wt(kg) for women
and so when giving infusions you need to calculate how much water deficit you have and give fluids according to how much free water does it have. I was told as medical students, we don't need to know the ones in between and so when I say 1L D5W is 1 L free water, it implies you correct for 1 L of water. Now I am not sure how much of this is needed for step 2ck, but we had to know them and I find it makes sense so I don't have to memorize bunch of random facts. I know it is needed for step 3 for sure.

Same is true when you are correcting Na you need to use the formula to see how much you correct every time you infuse, to avoid rapid corrections and problems like Central demyelination (pontine Syndrome) or on the other side rapid correction of hypernatremia and causing cerebral edema. and just incase the formula for that is:
Change in serum Na= [Infusate Na - Serum Na] / TBW + 1L

and oh, my all time fav please do not forget to check glucose before correcting Na, I have seen that in questions. treaksy...so correct for Hyperglycemia when evaluating your Na labs

and last for how D5W removes Na...I think I word it badly... but what I meant was: For Hypervolemic Hypernatremia you give diuretics and if renal failure you use dialysis. In both cases you are removing volume. and giving D5W gives you back volume you need and without Na, so you dilute Na remaining Na and wooohoooo problemo solved

Hope that clarifies it
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Old 04-05-2011
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v.useful material discuusion
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Old 04-05-2011
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For more details on fluid management, I found the following document helpful:
http://www.med.uvm.edu/pediatrics/do...Management.pdf
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