What is hemodialysis?

Hemodialysis is a painless therapeutic procedure that removes wastes and water from your blood. It is recommended in renal failure patients and performs the function of normal healthy kidneys.

According to National Kidney Foundation guidelines, dialysis is needed when the kidney function drops to 15% or less, and in the presence of severe related symptoms such as shortness of breath, fatigue, muscle cramps, nausea, or vomiting.

In patients with renal failure, hemodialysis helps to control blood pressure and stabilize the blood levels of vital minerals, such as potassium, sodium, and calcium.

Hemodialysis is not a cure for renal failure but it gives you relief from symptoms and not only extends your life but can also help you carry on an active life despite failing kidneys.

You’ll, however, need to follow a strict treatment schedule, take medications regularly, and follow certain dietary restrictions.

In most cases of acute kidney failure, dialysis may only be needed for a short period till the condition of the kidneys improves. However, chronic kidney failure (CKD) cases will need dialysis for the rest of their life.

 How does the dialyzer clean my blood?

Hemodialysis is done with the help of the dialysis machine, which is made up of a series of membranes that act as filters and a special liquid called dialysate.  The dialyzer is part of the dialysis unit and consists of a filter encased in plastic and inserted into a holder of the dialysis machine. This filter cleans up your blood from the impurities.

For this to happen, your blood has to pass through the dialyzer. To facilitate this, the doctor needs to create an access into your blood vessels with a minor surgery, usually in your forearm.

The dialyzer consists of two compartments separated by a thin membrane. One compartment is for your blood and one is for the dialysate. It has four ports, one inlet and one outlet each for blood and dialysate.

This structure enables the dialyzer to remove the excess wastes, such as urea, creatinine, potassium, and extra fluid from the blood, when the patient’s failing kidneys are unable to perform that task. Essential contents such as blood cells, protein, and other important contents are not filtered because they are too big to pass through the membrane,

What is the duration of each hemodialysis session?

Your nephrologist will advise you on the dialysis schedule and dose. In a dialysis center, one session of hemodialysis lasts for about 4 hours and is usually recommended 3 times a week.

You can do dialysis at home too with the right infrastructure, where you can do dialysis treatment more frequently, typically four to seven times per week for a shorter duration each time.

It’s important that you stick to your doctor’s orders because studies have shown that undergoing the right amount of prescribed dialysis prevents hospitalization and extends your life.

Tests to know if dialysis is working

During the course of dialysis, your dialysis team will monitor your therapy and perform monthly lab tests, which will indicate whether you are getting the correct amount of dialysis sessions.

Kt/V and Urea Reduction Ratio (URR) are two measures used by the dialysis care team to determine whether the dialysis and the dialysis dose are adequate.

Kt/V indicates the amount of blood from which urea has been removed and URR is the percentage of urea cleared from your body.

To ensure that you are getting enough dialysis:

  • your Kt/V should be at least 1.2 or
  • your URR should be at least 65 percent.

Hemodialysis can be done in a hospital, in an independent dialysis center, or at home. You and your doctor will decide on the ideal place based on your medical condition and your preference.

Do I need to eat a special diet when on dialysis?

The dietary restrictions for a patient on dialysis differ from person to person and the extent of kidney damage. It is very much advisable to ask a renal dietician to plan a special diet for you.

However, broadly, while on dialysis, your doctor is likely to recommend limiting the following:

  • Limit sodium intake. Sodium is a major constituent of many food items mainly table salt. When diseased, the kidneys are unable to filter out the excess sodium from the blood. The average American consumes 3,400 mg of sodium a day. The recommended daily allowance (RDA) for people with CKD and dialysis patients varies from 750 mg – 2000 mg per day.
  • Limit potassium intake. Though potassium is an essential electrolyte for your body, people with kidney disease should limit its intake. Patients on hemodialysis should limit potassium intake to 2.7–3.1 g/day and peritoneal dialysis patients should not consume more than 3–4 g/day. However, monitoring serum potassium in both cases is essential for adjustments to be made.
  • Limit phosphorus intake. Diseased kidneys are unable to eliminate excess phosphorus from the blood. Therefore, doctors recommend less than 800 mg of phosphorus per day.
  • Make sure to include high-protein foods in your diet.
  • Consult your dietician about the amount of fluid you can consume, including water, tea, coffee, and other beverages.

Are dialyzers reused? If so, is it safe?

During hemodialysis, a hemodialyzer (filter), or the artificial kidney can be reused more than once for the same patient.  Reuse of a hemodialyzer means that the same hemodialyzer is used more than once for the same patient.

However, before reuse, the dialyzer has to be cleaned and disinfected after each treatment according to careful guidelines. It is then considered safe.

The basic procedure for dialyzer reuse involves four steps: rinsing, cleaning, performance testing, disinfection and sterilization. This can be performed manually or with automated equipment.

Before each treatment, the dialyzer must be tested to make sure it is still functioning well. If it does not function well, it should be discarded and a new one should be used.

The dialyzer can be reused as long as it passes the three important tests:

1.       Total cell volume (TCV) should be at least 80% of what it first was.

2.       Urea reduction volume (URR) should be at least 65%

3.       Kt/V should be at least 1.2

However, if you do not wish to reuse your dialyzer, you can ask for a new one at every session. It will then cost you more.

Can dialysis patients continue to work and travel?

Yes. Dialysis patients can continue to work after a few sessions when they have gotten used to dialysis. However, you may have to change your duties if they involve a lot of physical labor such as lifting heavy objects or digging.

Dialysis patients can travel, but before you travel, you must make an appointment for dialysis treatments at another center of your destination. The dialysis staff at your center may be able to help you arrange this appointment.

 Complications of Hemodialysis

Patients on hemodialysis can develop major side effects and complications. Preventing these complications is important to extend life and improve the health and well-being of the dialysis patient.

Most of them occur from the creation of the dialysis access, which facilitates your blood to move through the tubes to the dialysis machine where it is purified as it passes through the dialyzer.

Other complications arise due to the impact of the fluid and electrolyte imbalance in the body on blood pressure and heart function.

Complications include:

  • Infection
  • Hypotension
  • Fluid overload
  • Electrolyte abnormalities such as hypokalemia
  • Dialysis Disequilibrium Syndrome (DDS)


The hemodialysis artificial access point in the body exposes the closed vascular system. This puts the dialysis patient at a constant risk of infection because the access point provides an opening for the bacteria and other microorganisms to enter the bloodstream.

Symptoms of infection would typically include:

  • Swelling, redness, and pain at the access point
  • Presence of pus
  • Fever with or without chills

Keeping the access point clean and maintaining optimal hygiene can reduce the risk of infection to a great extent. Antibiotics are used to treat the infection if it sets in. Blood thinners may be used to prevent blood clots.


Hypotension is common during the hemodialysis procedure. The dose and speed of the dialysis procedure can be responsible for removing fluids from the blood too fast. At times, this can cause the pressure in the blood vessels to suddenly fall sharply.

This can cause symptoms such as:

  • Abdominal pain
  • Nausea and vomiting
  • Muscle cramps
  • Anxiety
  • Dizziness
  • Clammy skin
  • Blurred vision
  • Increased risk of clots

To minimize and prevent this risk of complications of hypotension, it is necessary to adhere to the recommended fluid restrictions.

Electrolyte abnormalities: Hypokalemia

Electrolyte imbalance is another complication of hemodialysis that can develop because hemodialysis not only removes toxins and excess fluid from the body but also many of the essential electrolytes like potassium. However, adhering to a proper diet will minimize this risk.

However, the presence of comorbidities like diabetes or taking angiotensin-receptor blockers (ARBs) for hypertension significantly increases your risk of hypokalemia (abnormally low potassium in the blood) even if you adhere to the prescribed diet for hemodialysis.

Potassium helps to regulate fluid balance, muscle contractions, and nerve signals in the body. A fall in its level can cause symptoms such as fatigue and weakness, muscle cramps, and palpitations.

Severe hypokalemia, defined by levels below 2.5 mmol/l, can cause serious complications such as rhabdomyolysis (breakdown of muscle tissue), ileus (lazy bowels), irregular heartbeats (arrhythmia), atrial or ventricular fibrillation, respiratory failure, and paralysis.

However, the risk of hypokalemia is low if you strictly follow the prescribed diet and treatment plan.

Fluid Overload

Fluid overload (hypervolemia) occurs when the kidneys are unable to remove enough fluid from the body. This can happen in hemodialysis if the dialysis machine is not calibrated appropriately.

Symptoms of hypervolemia include:

Dialysis patients usually need to limit their fluid intake to 32 ounces per day. Managing your fluid restrictions can significantly reduce the risk of hypervolemia.

If overload still persists or develops soon after hemodialysis, your nephrologist will make certain changes in your treatment plan. Untreated hypervolemia can lead to an enlarged heart, congestive heart failure, and arrhythmias.

Dialysis Disequilibrium Syndrome

Dialysis disequilibrium syndrome (DDS) is a neurological condition that is rare and affects people who have just started treatment with hemodialysis. It can also be seen in regular dialysis patients who are irregular in their dialysis schedule.

The body responds to the dialysis procedure by releasing inflammatory chemicals, which causes swelling of the brain (cerebral edema).

Symptoms of DDS may include:

  • weakness
  • faintness
  • nausea and vomiting
  • headache
  • muscle cramps

DDS is usually short-lived and goes away as the body adapts to dialysis. Hypotension is treated with intravenous saline and mannitol injection is used to relieve the cerebral edema.

Survival and mortality rates

Ten percent of the world’s population suffers from chronic kidney disease (CKD), and millions die each year because they do not receive affordable treatment. In the United States, kidney failure affects almost 750,000 people per year.

Presently only a little over 2 million people worldwide currently receive dialysis treatment or a kidney transplant to stay alive. These people represent 10% of people who actually need treatment to live.

Mortality rates differ depending on the treatment. After one year of treatment, CKD patients on dialysis have a 15-20% mortality rate, with a 5-year survival rate being under 50%. Persons who have undergone kidney transplant enjoy a survival rate of about 80% after 5 years.

The average life expectancy of patients undergoing dialysis is 5-10 years. However, there are cases of patients on regular dialysis who have survived well for 2 or even 3 decades.

The key to long-term survival is strictly following your dialysis schedule, taking your meds regularly, and always sticking to your prescribed diet. If you suffer from any comorbidity, keep it under control.