Types of Dialysis: How They Work and Their Side Effects

Disclaimer: This content is for educational purposes only and is not a substitute for professional clinical advice from a healthcare provider.

Dialysis is a life-sustaining treatment for kidney failure. When the kidneys can no longer filter waste products, excess fluid, and salts from the blood, dialysis takes over that function artificially. There are several types of dialysis available, each with its own method, schedule, and set of considerations. Understanding the differences – and being aware of potential side effects – helps patients and their families make more informed decisions about their care.

What Is Dialysis?

Dialysis replaces some of the filtering functions of healthy kidneys. It removes waste products (such as urea and creatinine), excess fluid, and electrolytes (such as potassium and phosphate) from the blood, and helps regulate blood pressure. Dialysis does not replicate all kidney functions – it cannot produce hormones such as erythropoietin or activate Vitamin D – but it is essential for sustaining life when the kidneys have failed.

In Singapore, dialysis is the most common treatment for end-stage renal disease (ESRD), alongside kidney transplantation.

Types of Dialysis

Haemodialysis (HD)

Haemodialysis is the most widely used form of dialysis in Singapore. Blood is drawn from the patient’s body through vascular access – typically an arteriovenous (AV) fistula surgically created in the arm – pumped through a dialysis machine containing a dialyser (artificial kidney), filtered to remove waste and excess fluid, and returned to the body.

Each session typically lasts three to four hours and is performed three times per week at a dialysis centre. Trained nurses oversee every session.

A minor surgical procedure is required before starting haemodialysis to create the vascular access. The most common and preferred form is the AV fistula, as it has the lowest risk of infection and the longest lifespan. A graft (synthetic tube) or a catheter may be used when a fistula is not feasible.

Peritoneal Dialysis (PD)

Peritoneal dialysis uses the peritoneal membrane – the natural lining of the abdominal cavity – as a filter. A soft catheter is surgically inserted into the abdomen, and a sterile dialysis solution (dialysate) is introduced. Waste products and excess fluid pass from the blood vessels lining the peritoneum into the dialysate. After a prescribed dwell time, the used solution is drained and replaced with fresh solution. This process is called an exchange.

PD is performed daily and can be done at home, at work, or while travelling.

CAPD (Continuous Ambulatory Peritoneal Dialysis)

CAPD is performed manually during the day without a machine. Patients typically perform three to five exchanges per day, each taking approximately 20 to 30 minutes. Between exchanges, the dialysis solution dwells in the abdomen while patients go about their normal activities.

APD (Automated Peritoneal Dialysis)

APD uses a cycler machine that automatically performs multiple exchanges overnight while the patient sleeps, over eight to ten hours. Patients are generally free from exchanges during the day, though some may require one additional daytime exchange.

Haemodiafiltration (HDF)

Haemodiafiltration is an advanced form of haemodialysis that combines diffusion (like standard HD) with convection – using pressure to remove a larger volume of fluid and drag larger toxin molecules (known as middle molecules) across the membrane. This results in superior toxin clearance compared to conventional HD.

Clinical evidence, including the 2023 CONVINCE trial, shows that high-volume HDF reduces all-cause mortality by approximately 23 per cent compared to standard haemodialysis. HDF requires specialised equipment and ultrapure water, and is available at select dialysis centres in Singapore, including KDF.

Continuous Renal Replacement Therapy (CRRT)

CRRT is a slow, continuous form of dialysis used in intensive care units (ICUs) for critically ill or haemodynamically unstable patients who cannot tolerate the rapid fluid shifts of conventional haemodialysis. Unlike standard haemodialysis, CRRT runs continuously over 24 hours. It is not used for long-term kidney failure management.

Haemodialysis vs Peritoneal Dialysis: A Comparison

Side Effects of Dialysis

Dialysis is a life-saving treatment, but it can cause side effects – some occurring during treatment and others developing over time. Being aware of them helps patients recognise and report symptoms early, and helps care teams adjust treatment plans accordingly.

Side Effects of Haemodialysis

Intradialytic hypotension (low blood pressure during treatment) The most common side effect of haemodialysis. Rapid removal of fluid can cause a sudden drop in blood pressure, leading to dizziness, nausea, shortness of breath, or fainting. It is managed by adjusting the rate of fluid removal and ensuring patients do not come to treatment with excessive fluid overload.

Muscle cramps Often caused by fluid and electrolyte shifts during treatment, particularly when too much fluid is removed too quickly. Staying within recommended fluid intake limits between sessions reduces the risk.

Fatigue after treatment Many patients feel tired or drained for several hours after a haemodialysis session. This is sometimes called the “washed out” feeling and may improve as the body adjusts to dialysis.

Access site complications The AV fistula or graft can develop blood clots (thrombosis) or become infected. Regular monitoring of the access site and prompt reporting of any changes in flow, swelling, or redness is important.

Itchy skin (pruritus) Common in dialysis patients, often linked to excess phosphate in the blood or dry skin. Managing phosphate levels through diet and medication helps reduce itching.

Anaemia Dialysis patients frequently experience anaemia due to reduced erythropoietin production by the failing kidneys. It is managed with erythropoietin-stimulating agents and iron supplementation.

Restless legs syndrome Some patients experience uncomfortable sensations in the legs, particularly at rest or during dialysis sessions.

Side Effects of Peritoneal Dialysis

Peritonitis The most serious complication of peritoneal dialysis. Infection of the peritoneal cavity – typically caused by bacteria entering through the catheter during an exchange – can be life-threatening if not treated promptly. Strict hygiene during all exchanges is essential for prevention.

Exit site and tunnel infection Infection around the catheter exit site or along the tunnel under the skin can occur if hygiene protocols are not followed. These require prompt antibiotic treatment.

Hernia The pressure of dialysis fluid in the abdomen increases the risk of hernias, particularly at the belly button or groin. Avoiding heavy lifting and reporting any bulges promptly reduces this risk.

Weight gain The dialysis solution contains glucose (dextrose), which is absorbed into the bloodstream during each exchange. Over time, this can lead to unintended weight gain and elevated blood sugar – a particular concern for diabetic patients. Some patients may benefit from icodextrin-based solutions that contain less glucose.

Abdominal discomfort Some patients feel bloated or uncomfortable when the dialysis solution is dwelling in the abdomen, particularly when standing. APD, which performs exchanges while lying down overnight, tends to cause less discomfort.

Long-Term Side Effects Common to Both

Regardless of dialysis type, patients on long-term dialysis may experience:

• Cardiovascular disease – the leading cause of death in dialysis patients; dialysis patients have a significantly elevated risk of heart attack, stroke, and heart failure compared to the general population.^[2]
• Bone and mineral disease – imbalances in calcium, phosphate, and Vitamin D from kidney failure cause weakened bones, increased fracture risk, and vascular calcification over time
• Dialysis-related amyloidosis – a long-term complication of haemodialysis caused by accumulation of beta-2 microglobulin, a middle molecule not efficiently removed by standard HD; leads to joint pain and carpal tunnel syndrome; HDF significantly reduces this risk
• Malnutrition – reduced appetite, dietary restrictions, and protein loss during dialysis can contribute to muscle wasting and malnutrition if not actively managed
• Depression and psychological distress – living with kidney failure and dialysis dependency has a significant psychological impact; addressing mental health is an integral part of holistic kidney care

How to Manage Dialysis Side Effects

Most dialysis side effects can be reduced or managed with the right approach:

• Follow your fluid and dietary guidelines – staying within recommended fluid, sodium, potassium, and phosphate limits between sessions significantly reduces the risk of intradialytic hypotension, cramps, and itching
• Monitor your access site daily – report any signs of infection, reduced blood flow, or unusual changes promptly
• Take all prescribed medications – including blood pressure medications, phosphate binders, and erythropoietin-stimulating agents
• Attend all scheduled sessions – missing or shortening dialysis sessions allows toxins and fluid to accumulate, worsening side effects and increasing cardiovascular risk
• Work with your dietitian – a kidney dietitian can personalise your dietary plan to reduce side effects and maintain adequate nutrition
• Seek psychosocial support – speak to a social worker or counsellor if you are experiencing depression, anxiety, or emotional distress related to dialysis

At KDF, our wrap-around care programmes – including dietary counselling, physiotherapy, and psychosocial support – are designed to help patients manage the challenges of dialysis and maintain the best possible quality of life.

Which Type of Dialysis Is Right for You?

There is no universally superior dialysis modality. The right choice depends on your medical condition, lifestyle, home environment, and personal preferences. Key considerations include:

• Medical suitability – some patients are not medically suited to one modality or the other; your nephrologist will advise
• Lifestyle and independence – PD offers greater flexibility for working patients; HD provides nursing support at a centre
• Home environment – PD requires a clean, suitable space at home and personal discipline; HD does not
• Cardiovascular health – PD is generally gentler on the heart than HD and may be preferable for patients with severe cardiac conditions
• Access – patients who cannot develop an adequate AV fistula may be better suited to PD

Discuss all options thoroughly with your nephrologist before making a decision. If circumstances change – medically or personally – it is also possible to switch modalities with your care team’s guidance.

Frequently Asked Questions

What are the two main types of dialysis? The two main types are haemodialysis and peritoneal dialysis. Haemodialysis filters blood externally using a machine at a dialysis centre. Peritoneal dialysis uses the lining of the abdomen as a natural filter and can be performed at home.

What is the most gentle form of dialysis? Peritoneal dialysis is generally considered gentler on the cardiovascular system than haemodialysis because it removes fluid continuously and gradually rather than in concentrated three-to-four-hour sessions. Among haemodialysis modalities, haemodiafiltration is associated with better haemodynamic stability and fewer side effects than standard HD.

What are the most common side effects of dialysis? The most common side effects of haemodialysis include low blood pressure during treatment, muscle cramps, fatigue, and itchy skin. For peritoneal dialysis, the most significant risks are peritonitis, exit site infection, and hernias.

How do you know if dialysis is working? Your care team monitors blood tests (including urea, creatinine, potassium, and phosphate levels) before and after sessions to assess dialysis adequacy. You should also feel generally better between sessions with controlled fluid balance and stable blood pressure.

Can dialysis side effects be prevented? Many side effects can be minimised through strict adherence to dietary guidelines, consistent attendance at all sessions, proper access site care, and taking all prescribed medications. Your care team will work with you to adjust your treatment plan if side effects are problematic.

Dialysis Support in Singapore

Living with dialysis is a significant adjustment: physically, emotionally, and practically. With the right support, most patients are able to manage their treatment effectively and maintain a good quality of life.

The Kidney Dialysis Foundation (KDF) provides subsidised haemodialysis and haemodiafiltration for needy kidney patients across Singapore, alongside comprehensive wrap-around support including dietary counselling, physiotherapy, psychosocial care, and patient education. Contact KDF to find out about eligibility, our dialysis programmes, and how we can support you or your loved one through the kidney failure journey.

Resources

[1] The CONVINCE Trial Investigators – High-Volume Haemodiafiltration versus High-Flux Haemodialysis for Kidney Failure (CONVINCE): A Randomised Trial

[2] American Heart Association / Circulation – Cardiovascular Disease in Chronic Kidney Disease: From the Patient Perspective to the Cardiologist’s Perspective