Hemodialysis

Hemodialysis is a treatment that uses a machine to clean the blood when the kidneys can no longer do that job well enough on their own.

Healthy kidneys filter waste products, excess salt, and extra fluid from the blood every minute of the day. When the kidneys fail or work very poorly, these substances build up and can become life-threatening. During hemodialysis, blood is drawn out of the body through a needle or a small tube, passed through a device called a dialyzer (an artificial filter), and then returned to the body cleaned. The dialyzer works like a sieve: waste and excess fluid pass out through a thin membrane (a very fine wall), while blood cells and proteins stay in the blood where they belong.

Hemodialysis is used when the kidneys have lost so much of their filtering ability that the body can no longer stay in balance without outside help. The most common reasons a doctor recommends hemodialysis include:

• End-stage kidney disease (ESKD) — permanent, severe kidney failure, often caused by diabetes or long-term high blood pressure.
• Acute kidney injury (AKI) — a sudden, sometimes temporary, loss of kidney function caused by severe illness, major surgery, or certain medicines.
• Dangerous build-up of potassium in the blood (hyperkalemia), which can disturb the heart rhythm.
• Severe fluid overload — when the body holds so much extra water that the lungs or heart are at risk.
• Uremia — a toxic state caused by very high levels of waste products in the blood, leading to confusion, nausea, or seizures.
• Poisoning or overdose with a substance that can be removed by dialysis.

Hemodialysis is not suitable for everyone. Doctors may consider other approaches or a different form of dialysis in some situations:

• Patients whose blood vessels are too damaged or too narrow to allow safe access for the machine.
• People with very low blood pressure that tends to drop dangerously during sessions.
• Patients who prefer a home-based dialysis method and are medically suitable for it.
• Those whose overall health is too fragile to tolerate the fluid shifts that hemodialysis causes.

Hemodialysis is a life-sustaining treatment, but like any medical procedure it carries recognised risks, which the care team monitors closely at every session.

• Low blood pressure (hypotension) during the session — the most common problem; it can cause dizziness, cramps, or faintness.
• Muscle cramps — often felt in the legs when fluid is removed quickly.
• Infection at the access site — the needle entry point or catheter (tube) can introduce bacteria into the bloodstream if not kept strictly clean.
• Clotting of the access — the arteriovenous fistula (a surgically connected artery and vein used for access) or graft can become blocked.
• Anaemia (low red blood cell count) — the kidneys normally signal the body to make red blood cells, and damaged kidneys may not do this well.
• Bone and mineral problems — imbalances in calcium and phosphorus can weaken bones over time.
• Itching — a common complaint linked to waste products and mineral imbalances.
• Sleep problems and fatigue between sessions.
• Rarely, air entering the blood circuit (air embolism) — machines have alarms to detect and prevent this.
• Rarely, an allergic reaction to the dialyzer membrane.

Preparing for hemodialysis involves steps taken days or weeks before regular sessions begin, as well as things to keep in mind before each individual session.

Before starting a hemodialysis programme, a surgeon usually creates a vascular access — a way to repeatedly reach the bloodstream safely. The most common type is an arteriovenous fistula (AVF), made by connecting an artery and a vein in the arm. This minor operation needs several weeks to heal before it can be used. If dialysis is needed urgently, a temporary catheter (a soft tube) may be placed in a large vein in the neck or chest instead. Your care team will explain which access is planned for you.

Tests that are typically run before or during the early phase of dialysis include:

• Blood tests to measure kidney waste products (creatinine and urea), electrolytes (such as potassium and sodium), and blood count.
• Ultrasound (USG) of the kidneys and sometimes the blood vessels in the arm.
• Chest X-ray to check the lungs and heart size.
• Electrocardiogram (EKG) to check the heart's electrical activity.
• Blood pressure measurements taken in both arms.

Before each regular session, patients are usually asked to:

• Limit fluid intake in the hours before the session, as advised by the care team — the exact amount depends on how much the kidneys are still producing.
• Avoid applying creams or lotions to the access arm on session days, to keep the skin clean for needle insertion.
• Take only the medicines the kidney doctor (nephrologist) has approved for the hours before dialysis — some medicines are held until after the session.
• Report any fever, swelling, redness, or pain at the access site before the session starts.

During a typical hemodialysis session, the following steps occur — though the exact order and details can vary between units:

• 1. The patient sits or reclines in a chair next to the dialysis machine.
• 2. Staff check weight, blood pressure, temperature, and pulse before starting.
• 3. The access site (fistula, graft, or catheter) is cleaned carefully.
• 4. Two needles are inserted into the fistula or graft — one to draw blood out, one to return it — or the catheter lines are connected.
• 5. Blood flows slowly from the body through tubing into the dialyzer, where it is filtered.
• 6. The cleaned blood returns to the body through the second line.
• 7. Throughout the session, staff monitor blood pressure, the machine's pressure readings, and how the patient feels.
• 8. At the end, needles are removed and firm pressure is applied to the access site to stop bleeding.
• 9. Weight and blood pressure are checked again before the patient leaves.
• 10. Most sessions last between three and five hours; frequency is usually three times a week, though your nephrologist will determine the schedule that fits your situation.

Because hemodialysis is an ongoing treatment rather than a single procedure, aftercare is a continuous part of life for most patients. The focus is on protecting the access site, managing diet and fluids, and attending every scheduled session.

• Rest for a short while after each session if you feel tired or lightheaded — most patients can return to gentle daily activities the same day.
• Protect the access arm: avoid tight clothing, watches, or blood pressure cuffs on that arm; do not let anyone draw blood or give injections through the fistula without specific instruction.
• Keep the access site clean and dry between sessions; watch for any signs of infection such as redness, warmth, swelling, or discharge, and report these promptly.
• Follow the fluid restriction set by your care team — drinking too much between sessions means extra work for the next dialysis and can strain the heart and lungs.
• Follow the kidney diet recommended by a dietitian (nutrition specialist): this usually means limiting foods high in potassium (such as bananas and potatoes), phosphorus (such as dairy and nuts), and salt.
• Take all medicines as prescribed by the nephrologist, including those that manage blood pressure, anaemia, and bone health.
• Attend all scheduled dialysis sessions — missing sessions allows waste and fluid to build up quickly.
• Keep regular follow-up appointments so the care team can review blood test results and adjust the dialysis prescription (the settings and duration) as your needs change.
• Inform the care team about any changes in how much urine you produce, unexpected weight gain between sessions, shortness of breath, chest pain, or fever.
• Patients who are candidates for a kidney transplant should discuss this option with their nephrologist, as transplantation is the only treatment that can end the need for dialysis.