What is Hemodialysis? Why it is necessary?


Temporary or definitive therapeutic process, used in the treatment of patients with kidney failure, which eliminates toxins (urea, uric acid) and water which is contained in too much quantity in the blood when the kidneys are not are better able to ensure their function of maintaining the body in a balance of water, sodium, potassium, and calcium as perfect as possible. Hemodialysis is the most widely used technique in the world. Its principle is based on the exchange between the person’s blood and a solution, the dialysate. Its principle is based on the exchange between the person’s blood and a solution, the dialysate. This exchange makes it possible to remove food waste from the blood, to rebalance the blood content of minerals such as sodium and bicarbonate, to eliminate excess water.

Hemodialysis can be performed:

  • In the center: For the most fragile patients (elderly people, people with cardiovascular disorders, etc.), this is the most suitable technique. A large medical team (permanent presence of a doctor) allows the person to perform their session in a reassuring environment. A session lasts 4 to 5 hours, sometimes more. The hours are generally not very flexible and can make it difficult to continue a professional activity, some centers offer dialysis in the evening and even at night.
  • In UDM (Medicalized Dialysis Unit): These structures allow more flexibility in the sessions and are particularly suited to people whose state of health does not require the permanent presence of a doctor throughout the session.
  • In self-dialysis: In these local centers, patients are cared for by a nurse, without permanent medical presence.
  • At home: The patient carries out all the phases of the treatment from home: preparation of the machine, assembly of the circuit, performance of the session, disinfection of the machine. The person will have previously undergone training (one to two months) to learn to be completely independent. The big advantage of this technique: the patient can choose the frequency, time, and duration of his sessions in consultation with his nephrologist. A loved one must necessarily be present during the sessions.

 Recently appeared, new “portable” dialysis machines allow the person greater autonomy and thus facilitate home dialysis. Small in size, these machines no longer require a connection to the water supply or to waste disposal. Still not very widespread, this mode of dialysis requires a daily frequency of dialysis.

Chronic hemodialysis:

For patients with end-stage disease, it is sometimes necessary to institute replacement therapy.

Hemodialysis (HD) consists of purifying the patient’s blood using an artificial kidney. Three sessions lasting from 3:30 to 4:30 hours are necessary each week to replace the work that the kidneys do 24 hours a day. This technique purifies the blood of toxins and excess water retained between each dialysis session. The blood is first taken by puncture of vascular access. It passes through a dialysis filter (dialyzer or artificial kidney), then it is reinjected into the patient’s body.

goals of hemodialysis:

  • The immediate goals of hemodialysis are to
  • Correct hydro electrolyte imbalances
  • Eliminate toxins

The longer-term objectives in renal failure are

  • Optimization of the patient’s functional state, comfort, and BP
  • Prevention of complications of uremia
  • The prolongation of survival

The optimal “dose” for hemodialysis is uncertain, but most patients respond well to 3-5-hour hemodialysis 3 times/week.  The dosage of hemodialysis can be varied by increasing the dialysis time, blood flow, membrane area, or porosity. 

Hemodialysis settings:

The hemodialysis centers

 The hemodialysis center is the hemodialysis type most common in the United States. Most treatments are done 3 times/week for 3 to 5 hours per session. The main advantage of central hemodialysis is that the dialysis staff has complete control over the dialysis. The dialysis technician cannulates the fistula, decides on the amount of fluid to be withdrawn, and performs the complete dialysis treatment under the supervision of the nurse and nephrologist.

The nocturnal hemodialysis centres

 The nocturnal hemodialysis centers are 3 times/week for 6 to 8 hours per session. This modality is most appropriate in patients with high fluid intake, low blood pressure, or difficulty controlling phosphorus. It is also attractive to those who work during the day but do not want dialysis at home.

Home hemodialysis

 Home hemodialysis is as viable as central hemodialysis. Patients treated with home hemodialysis have longer survival and better control of hypertension, phosphorus, and fluid levels, and a better quality of life than with central hemodialysis. Home hemodialysis is most often done 5-7 days a week for about 2 hours per session. However, home hemodialysis can also be done 3 times/week during the day or at night. 

Hemodialysis is usually performed through a surgically created arteriovenous fistula.

A central venous catheter:

A central venous catheter can be used for dialysis when an arteriovenous fistula has not been created or is not ready for use, or if the creation of an arteriovenous fistula is not possible. The main disadvantages of central vein catheterization are a relatively small caliber which does not allow blood flow high enough to achieve optimal clearance, a high risk of infection at the catheter, and a risk of thrombosis. Central venous catheterization for hemodialysis is best performed using the right internal jugular vein. Most internal jugular venous catheters are used for 2 to 6-week hemodialysis when very strict aseptic skincare protocols are followed and use of the catheter is limited to procedures. Hemodialysis Catheters with tunneling and a subcutaneous woven sleeve have a longer lifespan (29-91% are functional at 1 year) and are useful when arteriovenous fistula cannot be created.

The common complications include:

Usually, these complications appear for unknown reasons, but some could be part of a first-use syndrome (when the patient’s blood comes into contact with the coprophil or cellulose membranes of the dialyzer) or a syndrome. Dialysis imbalance is thought to be caused by too rapid removal of urea and other osmolytes from the serum, causing osmotic movement of fluid in the brain. The most severe manifestations of dialysis imbalance are disorientation, restlessness, blurred vision, confusion and convulsions, and sometimes death.

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In hemodialysis, blood is removed from the body, filtered through a machine, and the filtered blood is returned to the body.

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In peritoneal dialysis, a cleansing fluid flows through a catheter to the lining of your abdomen which acts as a filter and removes waste products from your blood.

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