Reverse Osmotic mechanism of Dialysis Disequilibrium syndrome
Reverse Osmotic theory of urea
If you are a patient undergoing regular hemodialysis, you might already know this term “Dialysis Disequilibrium Syndrome”. If not you might be a medical professional having some interest in dialysis. So Dialysis disequilibrium syndrome is one of the unforgettable side effect of the dialysis.
What is dialysis?
Before discussing of reverse osmotic mechanism of dialysis disequilibrium syndrome, you should have a better understanding on what is dialysis and what is disequilibrium syndrome.
Hemodialysis (Haemodialysis) is the providing of natural renal functions artificially with the support of a machine. This include removal of waste products, removal of extra fluids and etc.
What is dialysis disequilibrium syndrome?
Dialysis disequilibrium syndrome or simply the disequilibrium is the collection of neurological features due to inappropriate dialysis. Usually this happens in first few dialysis. In addition there may be some other reasons too.
Reverse osmotic theory of Urea
Basic osmotic pressure of our body is maintained by two main ions. That is Sodium (Na+) and Urea. When we do our dialysis, there is a sudden reduction of the blood urea concentration.
When the Urea concentrations falls in the blood, it causes reduction of osmotic pressure in the blood.
However the usual osmotic pressure of the cells remains unchanged.
As a result there is a osmotic pressure gradient between cells and the blood. So, there should be either diffusion of the urea from cell to blood or diffusion of the water from blood to cell.
Reverse osmosis of urea in brain
In brain there is a special barrier between blood vessels and brain cells. That is called blood brain barrier (BBB). only selective solutes can passes through this membrane.
So when there is a osmotic gradient, only the water can cross the blood brain barrier but not the urea molecules. Therefore there is a flow of water molecules from blood vessels to brain cells.
At last there will be edema of the brain cells.
This is the basis of reverse osmotic theory of urea in dialysis disequilibrium syndrome.
