The majority of people with kidney failure clean their blood using haemodialysis (HD). Here you can find an overview of what exactly happens during an HD treatment.
Most people who require dialysis undergo hemodialysis (HD). In Germany, more than 70,000 people regularly undergo hemodialysis. This makes it the most widespread procedure for cleaning your blood.
Hemodialysis - this is how it works!
In hemodialysis, the cleaning happens outside of your body (=extracorporeal) in a small artificial kidney. This is the dialyzer. It's like a sieve that lets some things through and others not. In technical terms, this sieve is called a semipermeable membrane.
In order to do this cleaning, blood is moved out of your body by using a vascular access. If you don't know anything about the different types of vascular access, you can check out the Mizu app to see what the different options are. The most common vascular access for haemodialysis is the AV fistula (=shunt).
From there, the blood is led via a tube system to the dialyzer and then back again and into the body.
The actual blood purification happens in the dialyzer. It is the "artificial kidney". Very roughly speaking, the rest of the relatively large HD machine just controls and monitors the whole process (and personalizes it for your needs). The machine also has a built-in pump that gently keeps the blood flowing.
How high must the blood flow be for hemodialysis?
The blood flow through the HD machine depends on the vascular access used. A shunt should provide a blood flow of at least 300 milliliters per minute. When dialysis is done via a catheter, sometimes only a blood flow between 200 and 300 milliliters can be achieved. The blood flow will be adjusted to you as much as possible. Let your dialysis team know if you have cramps or feel particularly dizzy at home after dialysis. This may be due to the blood flow rate or something else that your dialysis team can change.
What is the dialysis solution?
If you pay attention to what goes on in a dialysis center, you're probably wondering right now what the dialysis solution is. It is flushed past the dialyzer in the opposite direction of blood flow to better cleanse the blood. In physics, this is called the countercurrent principle.
How is the dialysis solution prepared?
In every dialysis center, the sterile dialysis solution (the fluid that arrives at the dialyzer) is prepared in a special water treatment process. First, the sterile fully desalinated water (permeate) is produced from drinking water in a complicated process that consists of several stages. This permeate runs into the back of your dialysis machine. The machine uses this water to create a dialysis solution that is optimized for you. To do this, it combines and mixes electrolytes and buffer substances. This process is closely monitored and controlled.
Alarms on dialysis
During the dialysis treatment, which lasts several hours, your blood pressure and other important values are checked several times. In addition, dialysis machines have alarms that quickly report malfunctions. Serious alarms can even stop the machine on its own if something more serious has happened. However, most of the machine's alarms are rather harmless, but are mandated by regulatory agencies. That's why, unfortunately, it often beeps regularly and sometimes a bit annoyingly in the dialysis center.
My hemodialysis is done - now what?
Once you are done with dialysis, the bloodlines are removed, and your vascular access is taken care of. You should then gently press the puncture sites yourself for at least 10 minutes. Ideally, you should do this with gloves. There are pressure aids, but you can always control the pressure better with your fingers in order to protect the shunt. Your dialysis catheter will be packaged well after your dialysis. Take special care that all blood openings are well closed and everything is completely clean.
How often do I have to dialyze?
Of course, hemodialysis takes up a lot of time, but it is very important that you keep to your rhythm. Normally, hemodialysis involves dialysis 3 times a week for 4-5 hours. Remember that healthy kidneys are usually working all the time. In comparison, dialysis time is quite short and intense. People who do hemodialysis at home and in their own homes often do dialysis almost every day. Healthwise, this is more beneficial for you, as it is closer to the natural way kidneys work.
