How a Dialysis Machine Works: A Simple Step-by-Step Guide
Our kidneys clean our blood all day. When they stop working well, a dialysis machine can do that job for them. This guide explains, step by step and in simple words, what happens inside the machine.
How does a dialysis machine work? A pump takes blood out of the body through a needle or tube. The blood goes through a filter called a dialyser. Inside the filter, a special cleaning fluid called dialysate pulls waste and extra salt out of the blood. The machine also takes out extra water. Then the clean blood goes back into the body. A session at a centre usually takes about 4 hours, three times a week.
First, What Do Kidneys Do?
Think of the kidneys as the body's cleaners. Every day they take waste and extra water out of the blood. That waste leaves the body as urine. The kidneys also keep the right amount of salt and minerals in the blood.
When the kidneys fail, waste and water build up in the body. This can make a person very sick. Dialysis does the cleaning job instead. It does not cure kidney failure, but it helps people feel better and live longer.
The Main Parts of a Dialysis Machine
| Part | What it does |
|---|---|
| Blood pump | Moves blood from the body to the filter and back |
| Dialyser (the filter) | The "artificial kidney" where the blood gets cleaned |
| Dialysate | A cleaning fluid that pulls waste out of the blood |
| Blood tubing | Soft tubes that carry the blood in and out |
| Sensors and alarms | Watch for air, leaks and wrong pressure, and stop the pump if needed |
| Screen | Lets the nurse set and watch the treatment |
Step by Step: What Happens During Dialysis
Step 1: Connecting the patient
The nurse puts two needles into a special spot in the arm called a fistula. One needle takes blood out. The other brings clean blood back. Some patients have a soft tube called a catheter instead, usually in the neck or chest.
Step 2: The pump moves the blood
A pump on the machine gently pulls blood through the tubes. Only a small amount of blood is outside the body at any time. The rest of the blood keeps flowing in the body as normal.
Step 3: The filter cleans the blood
The dialyser is full of thousands of very thin, hollow tubes. Blood flows inside these tubes. The cleaning fluid flows outside them, the other way. The tube walls have tiny holes. Waste and extra salt pass through the holes into the cleaning fluid. Blood cells are too big to pass, so they stay in the blood.
Step 4: Taking out extra water
The machine gently pulls extra water out of the blood too. Doctors call this ultrafiltration. The nurse sets how much water to take out, based on how much the patient gained since the last session.
Step 5: Clean blood goes back
The clean blood flows back into the body through the second needle. This loop keeps going for the whole session.
Step 6: The machine watches everything
All the time, the machine checks for air bubbles, blood leaks and pressure that is too high or too low. If something looks wrong, it stops the blood pump and sounds an alarm.
Why the Water Must Be Very Clean
The cleaning fluid is made by mixing special salts with water. During a session, the blood is separated from this fluid only by a very thin wall. So the water must be extremely clean. Dialysis centres use a water cleaning plant, called an RO plant, to make it safe. International standards such as the ISO 23500 series set how clean dialysis water must be.
Ways to Connect a Patient
- Fistula: a surgeon joins an artery and a vein in the arm. It is the best long-term choice. It gives strong blood flow and gets infected less often.
- Graft: a soft man-made tube joins an artery and a vein. It can be used sooner, but it gets infected or blocked more often.
- Catheter: a soft tube placed in a large vein in the neck, chest or groin. It is often used for a short time until a fistula is ready.
How Long and How Often?
At a dialysis centre, most people have dialysis three times a week. Each session usually lasts about 4 hours. Some people do dialysis at home, with shorter sessions more often. Your kidney doctor decides what is right for you.
The Pulse PDM-6000: How It Puts These Steps to Work
The Pulse PDM-6000 haemodialysis machine is built for small clinics, dialysis centres and large hospitals. Here is how its features match the steps above:
| Step | PDM-6000 feature |
|---|---|
| Moving the blood | Blood flow from 50 to 600 ml/min |
| Cleaning fluid | Dialysate flow from 300 to 800 ml/min, kept at 35 to 39°C |
| Taking out water | Ultrafiltration up to 3600 ml/h, accurate to ±1% |
| Watching the patient | Air detection, blood leak detection, pressure alarms and self-tests |
| Checking the result | Built-in Kt/V monitoring, which shows how well the blood was cleaned |
| Staying safe in power cuts | 30 minutes of battery backup |
| Keeping it clean | Built-in disinfection of the fluid circuit |
Pulse also makes the parts used in every session: dialysers, blood tubing, fistula needles, transducer protectors and catheters.
Key Facts at a Glance
- A dialysis machine pumps blood through a filter called a dialyser, where a cleaning fluid (dialysate) pulls out waste and extra salt.
- The machine also removes extra water from the blood; this is called ultrafiltration.
- At a dialysis centre, most people have dialysis three times a week, about 4 hours each time.
- An AV fistula is the best long-term way to connect a patient for dialysis.
- Water used to make dialysate must meet strict purity standards, such as the ISO 23500 series.
Frequently Asked Questions
How does a dialysis machine clean the blood?
A pump sends blood through a filter called a dialyser. A cleaning fluid called dialysate flows on the other side of thin walls inside the filter. Waste and extra salt pass from the blood into the fluid, and the clean blood goes back into the body.
Does dialysis hurt?
Most people feel the needles going in, like a blood test. The cleaning itself does not hurt. Some people feel tired, cold or have cramps during or after a session. Tell the nurse if you feel unwell.
How long does one dialysis session take?
At a dialysis centre, a session usually takes about 4 hours, three times a week. Home dialysis may use shorter sessions more often.
What is the difference between haemodialysis and peritoneal dialysis?
Haemodialysis cleans the blood outside the body with a machine and a filter. Peritoneal dialysis uses the lining of the belly as the filter, with fluid put into the belly through a tube, and is often done at home.
How can I learn more about the Pulse PDM-6000?
Message Pulse on WhatsApp at +91 90711 01108. The team can share details, a demo and the price.
Sources
- Hemodialysis (NIDDK, US National Institutes of Health): how haemodialysis works, access types, session length
- ISO 23500-3 (International Organization for Standardization): water for haemodialysis
- Pulse PDM-6000 product sheet: machine details