[scientizscht (OP)]

Hello!

Can you tell me please how exactly haemodialysis (kidney dialysis) works?

I know you circulate the blood through a machine. What does that machine do? How can I clean the blood, since there can be numerous toxins and substances in the blood? How effective the cleansing is and how selective?

Thanks

[scientizscht (OP)]

Still no reply after so many days, that's extremely disappointing.

[Bored chemist]

The simple explanation is that the blood is passed through a tube . The tube is in a bath of water with salt and a few other nutrients.
The tubing is made from a semipermeable membrane.
It lets small molecules pass through it, but keeps bigger molecules like proteins in the tube.
So, for example, if the patient has taken an overdose of aspirin, the aspirin will diffuse through the walls of the tube into the tank of salt water.
That water is continuously replaced so the water never has much aspirin in it. So the direction of diffusion is from the blood to the salt water.
The aspirin is removed from the blood by diffusion.
https://en.wikipedia.org/wiki/Diffusion

The whole process is called dialysis.
https://en.wikipedia.org/wiki/Dialysis

[scientizscht (OP)]

The simple explanation is that the blood is passed through a tube . The tube is in a bath of water with salt and a few other nutrients.
The tubing is made from a semipermeable membrane.
It lets small molecules pass through it, but keeps bigger molecules like proteins in the tube.
So, for example, if the patient has taken an overdose of aspirin, the aspirin will diffuse through the walls of the tube into the tank of salt water.
That water is continuously replaced so the water never has much aspirin in it. So the direction of diffusion is from the blood to the salt water.
The aspirin is removed from the blood by diffusion.
https://en.wikipedia.org/wiki/Diffusion

The whole process is called dialysis.
https://en.wikipedia.org/wiki/Dialysis

As you describe it, then dialysis removes the hell out of the blood and nothing gets spared so that it only lets water pass through.

I mean all the cells are caught in the membrane, all the smaller molecules are diffused, so what is left? Are you sure dialysis gets rid of all the blood cells and proteins and smaller molecules?

[Bored chemist]

The walls of the tube are made from a semi permeable membrane.
Most of the blood flows through the tube and is returned to the body.
Only molecules small enough to pass through the membrane are removed.

[scientizscht (OP)]

The walls of the tube are made from a semi permeable membrane.
Most of the blood flows through the tube and is returned to the body.
Only molecules small enough to pass through the membrane are removed.

So this is purely mechanical filter and no adsorption is involved? Are we sure about that?

[Bored chemist]

So this is purely mechanical filter

Pretty much- though on a molecular scale.

Are we sure about that?

I'm sure about it. I can't say whether you are or not.

[evan_au]

Are you sure dialysis gets rid of all the blood cells and proteins?

If there is blood in your urine, or high quantities of protein, that points to a problem in the kidneys - perhaps a recent injury, or a diseased kidney.

For those with a diseased kidney, haemodialysis acts like a stand-in kidney. It should not lose blood cells or large amounts of circulating protein.