The roll of D5W in CHF patients

[firefighter523]

AZCEP, That is what I thought also. But, as I was reading an article, it is the opposite way around. The sugar molecules are actually burned up rapidly by the body, and drawn into the cells, (interstitial space) causing them to swell with the following of the water. That causes a reduced preload from the returning blood to the right atria. Thus, the purpose of the D5W.

Kev

[Ridryder 911]

That would be a lot of cellular activity.. I find error in this because of the water would be following sodium and as well as the rate of cellular activity. with only the amount of 5 grams of Dextrose per 1000 ml of dilution the glucose level is neal. P.E.T. scans use high glucose to detect cellular activity for cancer markers because of the activity level,but it is at a higher level of glucose, that enters the cell, not draws the fluid to the interstitial spaces.

R/R 911

[firefighter523]

So, many articles, so many people say diffent things Rid. That was my origional thought, because that would explain the hyperglycemic patient urinating alot. Since water follows sugar, well you know what I mean.

Kev

[Ridryder 911]

Okay your on the right tract, however 5 grams or 5000 milligrams of sugar per 1000 ml is very little and if the pancreas is working correctly you may not even elevate the glucose very much. Remeber some consider D5W isotonic, with little no gradient in osmalirity.

Okay a little patho for those that don't know about much about diabetes. Normally glucose absorbed during or after a meal and is not metabolized at the normal rate and therefore it starts storing or accumulating in the blood (hyperglycemia) to be excreted in the urine (glycosuria).

The glucose in the urine causes osmotic diuresis, leading to increase urine production (polyuria). The glucose is usually >180mg/dl for the sugar/glucose to be excreted into the urine. Then a stimulation of a protein breakdown to provide amino acids for gluconeogenesis (always loved saying that word) results in muscle wasting and weight loss. These classic symptoms occur only in patients with severe insulin deficiency, most commonly in type I diabetes. Many patients with type II diabetes do not have these symptoms and present with one of the complications of diabetes of the Type I.

That is why Type II is more difficult to dx. the 3 P's Polydispia, (increase thirst) polyphagia (increase hunger) & of course polyuria (increase urination) may be absent. Generally fatigue, weakness, malaise is some of the common symptoms.

Theoretically correct.. however clinically to place someone in hyperglycemia to dieurese someone is not proper choice..

Glad you are looking at it patho-physiologically ..

R/R 911

[kevkei]

Actually, D5W although initially is isotonic, once the glucose is taken up at the cellular level (which is quickly), it becomes hypotonic and worsens circulatory volume by drawing water into the vascular compartment due to osmosis and oncotic pressure.

As for the bad evaluation, look at the source. The guy would probably give a bad eval for not giving SL nitro to a RVI too.

[firefighter523]

OK, so now I am MOST definately confused. If it were hypotonic, wouldn't it draw water into the interstital space, and not the vascular space? This was the debate that we had, some said that the sugar draws water into the interstital space by the cells rapidly using the sugar, hence the water follows,decreasing preload. Some said the the sugar remains in the blood stream, causing water to be pulled into the vascular space, (hypertonic), diuresing the pulmonary edema. I know the concentration is too low to make a difference, but it is in our protocols for a reason. This debate was after class let out, therefore we didn't get to ask the question.

Kevin

[kevkei]

OK, so now I am MOST definately confused. If it were hypotonic, wouldn't it draw water into the interstital space, and not the vascular space? This was the debate that we had, some said that the sugar draws water into the interstital space by the cells rapidly using the sugar, hence the water follows,decreasing preload. Some said the the sugar remains in the blood stream, causing water to be pulled into the vascular space, (hypertonic), diuresing the pulmonary edema. I know the concentration is too low to make a difference, but it is in our protocols for a reason. This debate was after class let out, therefore we didn't get to ask the question.

Kevin

Sorry about that. I should have read what I wrote before submitting, but we got called out. It should have read more like this:

Actually, D5W although initially is isotonic, once the glucose is taken up at the cellular level (which is quickly) or processed into glycogen, it becomes hypotonic and will eventually worsen circulatory volume by first drawing water into the interstitial compartment due to osmosis (natural movement of solute and solvent) and oncotic (pull) pressure, but that fluid will eventually re-distribute into the vascular system. The only way to get rid of volume overload is third spacing (temporary), diuresis or dialysis. Keep in mind that osmosis and oncotic gradients cause fluid to continually move back and forth until an equilibrium is established.

I think that in reality, the dextrose in the solution does not stay in the vascular system for long enough to make a sensible change insofar as drawing interstitial fluid into the vasculature. What it does do is add whatever volume of water you administer to the total body volume that eventually ends up somewhere.

I know albumin is a heavy protein, and thus it pulls interstitial fluid back into the vascular space, (reduction of edema).

As for the CHF patient's you are talking about, where is the edema occuring that you are trying to correct? If it is pulmonary (left heart failure), attempts to redistribute fluid into the interstitium or vasculature won't really help. What you want to do is potentially decrease preload and afterload (hydrostatic pressure) and drive the edema back across the alveolar membrane. You aren't going to pull the pulmonary edema back across by increasing oncotic pressure, but if you decrease hydrostatic pressure, you will decrease the causal problem, then you can fix it.

Now I;m confused :wink:

[Ridryder 911]

Good posts Kev.. you are right.. then there is hydrostatic pressure & cellular metabolism of how much glucose is actually being distributed then let's not forget the Krebs cycle...etc.. #-o ...and most medics get confused on cations vs anions.. lol

Interesting but one can see how you will not see the forest for the trees....

R/R 911