Learning The Basics About Dialysis Membranes

As Joe Cosgrove has already said in this blog, dialysis is a method used on patients who have End Stage Renal Disease (ESRD) and whose kidneys are not able to filter blood properly in order to remove waste from it.

Renal Dialysis Technician

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As the dialysis process needs to filter blood waste, it should use a membrane in order to do so. Nowadays, most of these membranes are artificial ones, made out of polymer compound and blends. The most common polymer used to manufacture dialysis membranes is regenerated cellulose. However, many companies have developed modified cellulose membranes and even synthetic polymer membranes that are useful to filter blood.

Dialysis membranes are used clinically to remove waste from the patient’s’ blood. Most of this waste is made of uremic toxins that would otherwise cause blood intoxication. Besides removing waste, these membranes are responsible for providing the lacking dialysate ions the body needs to properly function.

As the number of patients who need dialysis increases so does a number of dialysis membranes that are required to treat them. Every year, at least 70 million square meters of dialysis membranes are used in the world. The most common type of dialysis membranes that is used to remove accumulated toxins is made of hollow fibers. A hollow fiber membrane included numerous materials, such as cellulose and other synthetic polymers.

Related: Which dialyser membrane to choose?

A Bit Of History

At first, dialysis membranes were made of cotton or cotton derived fibers. These membranes were thought to be natural ones and their structure would activate blood leukocytes and their immunity response. Due to this, the body started to develop inflammatory responses and finally, it was concluded that those membranes were not biocompatible with the body.

In time, scientists started to develop polymers made of both natural and synthetic compounds in order to mitigate the body’s response and further development of inflammatory reactions. This is how it was concluded that cellulose was more biocompatible to the body and didn’t cause as many reactions as cotton would do. Research institutions started to develop cellulosic membranes that were highly more compatible to the body and modified cellulosic membranes were born.

Many membranes have been developed over the years. Currently, we can find synthetic membranes with higher filtration capacity due to the larger size of their pores. This way, synthetic membranes can remove more particles than “natural” ones would do. This is how, besides the low flux cellulose membranes, five types of high-flux synthetic membranes can be found in the market today.


Biocompatibility: This characteristic describes how a membrane can cause a biological or biochemical effect on the body. In other words, is there is an inflammatory reaction in the body, the membrane is not biocompatible because it activated the leukocytes and made them react. This usually happens when natural fibers are not modified.

The main cause of death in dialysis patients is caused by these inflammatory responses. When healthcare providers use synthetic materials, patients have a better response to the dialysis treatment. This happens because high-flux synthetic polymers don’t activate leukocytes as unmodified cellulose membranes do, therefore they are considered to be more biocompatible to the body and their mortality rate associated with them is lower.

Impermeability: This characteristic is related to the membrane’s impermeability to dialysate impurities such as bacteria. Dialysate can be easily contaminated by other substances, allowing dangerous substances enter the body through the membrane directly to the blood stream.

Those membranes with larger pores, paradoxically, have fewer chances of filtering bacteria directly to the blood stream. This happens because membranes with larger pores are more absorbent that those with smaller pores. This way, synthetic membranes or cellulose modified membranes can absorb more bacterial products of dangerous substances for the body. These membranes are considered to be more impermeable to impurities.

However, it is recommended to use pure dialysate on patients, simply to avoid taking any potential risk that may affect the patient’s health. Using a synthetic membrane can be understood as taking an additional precaution.

Adsorption: As it was said before, membranes used during the dialysis process need to be absorbent. This way, they can remove any potential threat present in the dialysate fluid. There are some peptides, necrosis factors, and other substances that should be absorbed by the membrane in order to keep the body healthy.

In order to increase the membrane’s capacity to absorb impurities, most dialysis machines also include other inner systems such as beads with special properties meant to absorb harmful substances. This way, the absorption capacities won’t rely exclusively on the membrane, but also on the dialysis machine.


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Pore size: This characteristic varies from one material to another. Natural membranes have smaller pores and synthetic membranes have larger pores. Nowadays, scientists and researchers have created new synthetic materials and compounds that allow membranes to have larger pores, increase the flux and properly remove harmful substances.

Great Alternatives to Perform Dialysis at Home

Since the 1960’s home dialysis has been an alternative for patients with end-stage renal disease (ESRD). Joe Cosgrove knows that both home hemodialysis (HHD) and Peritoneal dialysis (PD) have been available for decades to those who barely had the chance to go to the hospital because of their condition. However, the usage of home dialysis only became popular during recent years.

At first, home dialysis was quite uncomfortable for both patients and healthcare providers. It was an exhausting and expensive procedure that would need patients to use huge machines. Nowadays, technology has made it possible for ESRD patients to have access to home dialysis comfortably. This way, patients get the chance to have a better lifestyle while being treated.


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Home Peritoneal Dialysis

Peritoneal dialysis is the most popular dialysis treatment that can take place at home. It is easy to handle and most patients who choose this type of procedure are able to take care of it on their own. People on Peritoneal dialysis are able to use the peritoneal membrane (which covers the intestine and other organs) in the abdominal cavity to filter any type of wastes from the blood.

This dialysis solution needs the patient to get a catheter installed in the abdominal cavity. This way they catheter will stay in the abdomen for several hours while toxins and fluids are filtered from the blood vessels through the peritoneal membrane and into a special solution called dialysate.

The reason why this procedure can be performed at home is that the dwell time is programmed and easy to handle. Once the patient got the waste filtered through the membrane and diluted in the dialysate, it will be drained out of the body and a new dose of dialysate will be introduced in the abdominal cavity so the cleaning process can start all over again.

This exchange process can be done with the assistance of a machine or manually. When the process is done manually by the patient at home, all the fluid held in the abdominal cavity will need to be removed before the new solution is injected. The patient will drain the solution thanks to the gravity force, placing the empty bag to receive the fluid onto the ground. Usually, the average amount of fluid that the patient will drain at home can reach the two liters and it can be drained within 10 to 20 minutes.

The most common peritoneal dialysis machine is called a cycler and it performs the exchange process automatically. Most patients at home choose to have this machine because it makes the dialysis process easier and faster, leaving enough free time to have a regular life. An ESRD patient will plug the catheter to the machine during the evening and the machine will work during its sleep, performing at least three exchanges.

Some patients choose to carry some dialysate in the abdominal cavity during the day and drain it out at night, once they are connected to the machine. Also, some patients need to perform one exchange during the day.

One of the most amazing things about this type of home dialysis is that the nurse and the doctor will need to teach the patient and its family how to use the machine and how to perform the dialysis manually. After three weeks, the patient will be able to take care of its condition on its own.

Related: 4 things you need to do to cope with dialysis

The Merck Home Manual of Medical Information - Dialysis

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Home Hemodialysis

This type of home dialysis has been the least common. Nevertheless, there are two types of hemodialysis available for patients who want to have it performed at home. The first type is called short daily home hemodialysis and the second type is known as conventional home hemodialysis.

The conventional type of home hemodialysis usually takes place three times per week and each session takes at least 3 hours. The procedure takes places regularly, just as it does at a dialysis center. Patients who choose to have this type of home dialysis, tend to spend the dialysis time watching television, on the computer or chatting on the phone.

The other type of home hemodialysis, known as short daily home hemodialysis, need to take place at least six times every week. Each session will take just a few hours depending on the patient’s weight, health condition, lab results and other factors. Since the blood gets to be cleaned every day, patients have the chance to have a freer fluid intake and side effects such as cramps, migraine, waves of nausea and low blood pressure are controlled since they are not likely to appear.

Unlike peritoneal dialysis, home hemodialysis cannot be done manually. This means that the patient will always need to be assisted by a machine in its house. Also, for safety reasons, a partner will need to be present during the entire session so the patient can get some help. Both the patient and its partner will need to be trained on how to handle and clean the machine. The training process can take up to six weeks to be completed.

Meet the future of dialysis!

For many years, the healthcare industry has doubled its efforts to offer better treatments to patients with an end-stage renal disease (ESRD). Joe Cosgrove knows that this hard work has helped millions of patients who probably wouldn’t have survived if it wasn’t because they had the chance to receive dialysis treatment. Most patients who had a kidney transplant which is being rejected by their bodies couldn’t find a kidney donor are very likely to go on dialysis for a long time.

The entire dialysis process involves filtering the patient’s blood in a machine (dialyzer) that is supposed to perform the kidney’s major functions. A dialyzer removes waste and excess of fluids from the blood and afterward returns the cleansed blood back to the body. This way some mineral chemical levels are kept stable and the patient’s body is able to function normally.


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Why are dialysis innovations important?

Without the dialyzer intervention, it would be very complicated for patients with ESRD to survive. Nowadays, the market for dialysis devices reaches billions of individuals worldwide and it is expected to grow dramatically in the next 5 years due to the increase in the number of patients with diabetes and hypertension. Patients who need dialysis in the United States often are young adults or children who have certain responsibilities such as going to school or work. For this reason, the current dialysis methods don’t meet their needs.

The healthcare industry knows how important it is to work hard to improve the current dialysis methods in order to provide a better future for the growing number of patients worldwide. Developing more effective and portable dialysis devices would allow some patients to stay away from renal transplants and its associated complications. Also, for patients that are currently on dialysis, improving the existing systems will help them reducing the chances of having anemia, low blood pressure or infections associated with dialysis.

It is important to notice that today most dialysis patients prefer to go under a hemodialysis procedure instead of using the peritoneal one. However, both procedures should evolve in the future and offer patients the chance of using portable units or go under faster filtering processes. There are some advantages and disadvantages related to any of the dialysis methods. Nevertheless, improving the way they operate is supposed to have a positive impact on the life of the billions of people who depend on dialysis to survive.

Related: New dialysis technology designed to be more user-friendly for patients, staff.


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Leaders in the dialysis industry

There are some companies such as Fresenius, Outset Medical, Baxter, and NxStage who control the dialysis device industry and are working hard to keep their leadership position. These companies are constantly launching new products and expanding their business in a way they can serve emerging markets and the growing number of patients in both developing and most developed countries.

The diversification in economic conditions and technological developments have allowed different companies to increase awareness towards dialysis, forcing manufacturers to invest in research and innovative therapies for patients with ESRD. Some of the most important changes which are defining the future of dialysis are listed below.

Outset Medical: During the Kidney Week, Outset Medical introduced the Tablo in the U.S. market. This device is a dialysis machine built from scratch which is supposed to operate exclusively in dialysis clinics, offering them the chance of using a simple system. The Tablo is supposed to be ready for sale in spring. The company is also working to develop a self-care unit for home dialysis applications.

NxStage: This company aims to work for the future of peritoneal dialysis, improving their groundbreaking System One home hemodialysis machine. The company’s CEO seems to be very confident about the progress they are making around home hemodialysis systems, eliminating the need of using bags of fluid during the peritoneal dialysis process. This system is also expected to be launched this year.

Baxter Health Care: With their Amia PD cycler, Baxter aims to change the way peritoneal dialysis is performed. Through the usage of Amia, the company offers patients a device which is easier to use, is light-weighted and offers State-of-the-art technology so caregivers can be connected to patients by using a system that looks a lot like a GPS.

Fresenius Medical Care: This is probably one of the companies which offer the most futuristic alternatives for the dialysis treatments. By researching and developing materials to improve the sorbent qualities of devices, Fresenius has developed a new home hemodialysis machine in collaboration with the Swiss engineering firm Debiotech SA. This way, Fresenius has been able to offer patients a new product platform with dialysis machines that are compact, easy to use at home and lightweight.

In conclusion, dialysis patients are a number one priority for healthcare companies dedicated to developing dialysis systems. This will allow caregivers to be connected to their patients while they are empowered to use more sophisticated, effective and portable dialysis devices.