I’d like to ask, why do we have disequilibrium syndrome in some patients in hemodyalisis? What does the shift in serum Urea does in the brain? I know it is rare now, but it is still discussed.
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Urea ist an ineffective osmole because it can permeate cell membranes. But this process needs a little bit of time. If you remove urea via dialysis (very fast) you can end up with a gradient between plasma and brain cells. This gradient is forcing water into the cells and you will get cerebral edema
I understood that a solute is or not an effective osmole not because of its ability to permeate a cell membrane but it’s a ability to create a gradient by “dragging water”. Am I wrong about this?
Saying urea isn’t an effective osmole is confusing to me, because of desequilibrium syndrome.
Unfortunately, I can’t explain it better…urea can move relatively freely over the cell membrane -> most of the time an ineffective osmole.
In the disequilibrium urea is cleared so fast from the vascular compartment, that for a short period of time it works as an effektive osmole. -> cerebral edema
You’re not supposed to create a relevant sodium gradient during dialysis. The sodium content of your dialysis fluid is +/- matched to the sodium content in your blood.
Of course. But I meant a gradient caused by Urea in hemodyalisis (chronic patients on their first sessions) and a gradient that occurs for example in a rapid correction of hyponatremia.
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Saying urea isn’t an effective osmole is confusing to me, because of desequilibrium syndrome.
https://pubmed.ncbi.nlm.nih.gov/15985519/
In the disequilibrium urea is cleared so fast from the vascular compartment, that for a short period of time it works as an effektive osmole. -> cerebral edema