Types of Hemodialysis

“Doctor, can you please help in deciding among the various types of hemodialysis? Which suits me the best?”, this is a question that I’m often asked.

Starting dialysis can be a confusing time for patients. Most patients research and learn about the two important types of dialysis: hemodialysis and peritoneal dialysis.

However, you would be surprised to know that hemodialysis can be further divided into various types. These types are decided based on factors that are unique to patients, thus allowing them to make a well informed decision.

As you might know, hemodialysis(“HD”) is the type of dialysis that uses a filter called hemodialyzer to purify blood. Blood is pumped out usually from the forearm and then pumped back in once it is purified. This process uses catheters or an AV fistula in order to gain access to the bloodstream.

HD is classified into subtypes based on the following considerations:

CriteriaTypes of HD
Type of filterLow flux
High flux
Frequency Nocturnal
Intermittent
Daily
LocationIn-center
Home
MiscellaneousSlow low efficiency dialysis (SLED)
Slow continuous ultrafiltration (SCUF)
Types of Hemodialysis

These types are briefly explained below:

Type of filter: High flux vs low flux dialysis

Hemodialysis requires the use of a dialyser to purify blood. This dialyser uses a membrane to separate the toxins from the blood. Flux refers to the permeability of the dialysis membrane. The permeability will affect the size of molecules that can pass and thus, affect the efficiency of dialysis.

  1. Low flux dialysis: 

These membranes were the earliest membranes used in dialysers. It usually includes cellulose membrane which has a small pore size. It allows urea to pass through it but larger molecules can’t be removed by this type of membrane. These are the commonest types of filters that are used in India. 

  1. High flux dialysis: 

As the name suggests, this type membrane has larger pore size. It allows better filtration. These membranes allow removal of greater amounts of larger waste molecules such as β2 microglobulin. The cost is higher than low flux dialysis. In countries with good health systems, high flux dialysis is the usual form of dialysis that is performed.

Frequency of dialysis: Nocturnal, intermittent, daily hemodialysis

Renal diseases like acute kidney failure can hamper kidney function for a short time. On the other hand, certain conditions can result in long term complications. Based on the duration of treatment, various methodologies can be used to make dialysis easier for the patient.

  1. Nocturnal dialysis:

Nocturnal dialysis refers to dialysis at night. This treatment approach focuses on performing dialysis while the patient is asleep. The process takes six to eight hours. Since it is a slow process, it is usually gentle for the patient’s body. However, some patients may find it uncomfortable. Also, this option is not available in all places. Kindly check with your nearby dialysis centre.

  1. Intermittent dialysis: 

Intermittent dialysis is done 2-3 times a week.

  1. Daily dialysis: 

As the name suggests, daily dialysis is done everyday. In patients with a chronic renal disease, intermittent dialysis may not be a viable option. Daily dialysis is done using a permanent catheter, which is replaced by an AV fistula over time. Diet of the patient on daily dialysis is not affected as much as in the other variants.

Depending on location : in-center vs home hemodialysis

HD can be performed at a dialysis centre or at home. 

  1. In-centre hemodialysis: 

HD is performed at a dialysis centre. It is done three to five times a week and is pre-scheduled. Technicians and medical staff perform the process. It takes four hours typically. In centre HD the default method in most countries/places including India. Old people and people without much social support prefer this type of treatment.

  1. Home hemodialysis: 

HD is often considered an in-Centre treatment. At home, HD can be done at the patient’s discretion. The patient and a caregiver (usually a family member or a friend) is trained to perform the process. It can be done everyday or thrice a day. Doing hemodialysis everyday can actually help with some symptoms like nausea, headache etc. This option, however, is not suited for everyone and is not available everywhere. Consult your nephrologist for details. 

Miscellaneous : slow low efficiency dialysis, slow continuous ultrafiltration

Some other terms related of HD which you may commonly encounter are:

  1. Slow low efficiency dialysis

In patients who require dialysis in the ICU but are very sick with low blood pressure, slow low efficiency dialysis or SLED is done. In this process, blood is slowly filtered using a dialyser. Since the process is slow, it doesn’t put strain on the heart. This allows it to be used commonly in patients with cardiac diseases.

  1. Slow continuous ultrafiltration

Slow continuous ultrafiltration or SCF is a technique used in patients with a fluid overload. The goal of SCF is to remove these excess fluids that may disturb fluid balance in the body. 

Even though these are the usual types of hemodialysis, they can be combined for the greatest benefit in a given patient. For example : a patient may be prescribed daily, high flux, home hemodialysis. 

Conclusion:

While many people know about the two main types of dialysis, not many know that even within hemodialysis there are many types. The best type for you can be suggested by your nephrologist. I hope this article was helpful. All the best!

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