Everything You Need to Know About A Dialysis Machine

As Joe Cosgrove has pointed out before in this blog, kidney plays a vital role in the functioning of the human body. Without them, the waste present in the blood couldn’t be removed, and most individuals would die within a few days. Sadly, these bean-shaped organs can fail and when that happens, the best option for patients is to go under dialysis.

Dialysis is a medical procedure that works as an artificial kidney. It takes place when a person’s blood is filtered with the help of a dialysis machine. This machine aims to mimic the regular functions of human kidneys. This way, it is able to remove toxic waste from the blood as well as the extra water that may be present in it.

dialysis_dialysis machine

Image courtesy of Matt Kowalczyk at Flickr.com

Each dialysis machine is built up in a similar way and healthcare providers and technicians know how to operate them in order to help patients filtering their blood. There is a list of parts and components that need to be well known by technicians in order to properly handle the dialysis machine. Below, you will find a list of these components with a brief description of each one of them.


The most common type of pump used during dialysis is known as Peristaltic pumps. These are tubes meant to drive different fluids, such as blood, water, saline, and dialysate. This type of tubes is ideal for dialysis since they let a higher volume of fluids flow without letting them be touched by human hands. Also, dialysis pumps are a flexible system that helps to push fluids forward with the help of motors (AC or DC motors) which speed can be regulated by the technician.

Some pumps are connected to a sensory system that allows them to automatically regulate the flowing pressure of fluids depending on the patient’s needs. Nevertheless, in order to properly function, pumps need to be configured in advance based on the type of fluid that is going to pass through them


Dialysis machines need to have a few electronic valves to operate properly. This happens since dialysis machines need to use variable mixing ratios that are only possible when different valves open and close at different times. This type of valves are solenoids which can be controlled with precision thanks to the action of stepper motors or another mechanism.


Most dialysis machines use different types of sensors. This happens because they need to monitor and regulate different parameters that take place during the dialysis procedure. Some of these parameters include motor speed, temperature, oxygen saturation, dialysate pressure, dialysate membrane pressure, and airflow.

Nowadays, dialysis machines usually have digital outputs that allow the technicians to know what is going on during the dialysis procedure. When they don’t have these digital outputs the signal sent by the sensors needs to be amplified and digitized before reaching the controller. In order to be more accurate, a series of ADC resolutions are used and the sampling speed varies.

Cleaning system

A dialysis machine can be used to treat many different patients. This is why it needs to be cleaned before each session and components that are going to be reused must be properly sterilized too. Each machine can be cleaned in a different way, but most of them have the same system.

Technicians need to heat water to high temperatures so it can sterilize the tubes and each part of the dialysis machine when it runs through them. The inner and outer circuit of the machine needs to be cleaned with that water by activating the cleaning mode of the machine. However, there are different types of machines that require this process to be monitored and controlled.


The syringe is an external element used to pump substances into the dialysis machine. This procedure is needed since the blood tends to clog the machine’s pumps and a drug called heparin needs to be injected into the tubes to keep them unclogged. The syringe is attached to the pumps in most machines.


Image courtesy of wistechcolleges at Flickr.com


The dialyzer is probably the most important piece of the dialysis machine because it is where the blood is filtered. Here a filtering membrane and a cleaning solution called dialysate can be found. The dialyzer is, in general terms a blood compartment.

Dialysate Solution

The dialysate is a solution made of purified water, an acid and bicarbonate that can be found inside the dialyzer. It is meant to remove waste from the blood thanks to the action of the minerals and electrolytes present in the solution. Dialysate never mixes with the blood; it simply takes waste away with the help of a filtering membrane.

Once the blood is cleaned and filtered thanks to the combined action of both the dialyzer and dialysate, it is pumped back into the patient’s body. This process takes place in the form of a moving current since only one pint of blood can be treated at the time.