Kidney support (dialysis) in intensive care
A plain-English guide for families explaining how a filtering machine temporarily does the work of the kidneys in intensive care when they suddenly stop working, and what recovery may look like.
✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review
In short
- A filtering machine temporarily does the kidneys' job — cleaning the blood and removing extra fluid — when the kidneys suddenly stop working.
- In intensive care it is usually run slowly and continuously because very ill people tolerate gentle treatment better.
- It supports the body while the underlying illness is treated; it does not, by itself, make the kidneys recover.
- Many people's kidneys recover and the machine is stopped, but recovery can be slow and a few people need long-term dialysis.
A plain-English summary. The detail — including risks and recovery — is below.
At a glance
A general guide. Your specialist will give you advice for your situation.
Removes waste products that build up when the kidneys stop working
Where the underlying illness is so severe that organ support cannot lead to recovery, comfort-focused care may be more appropriate.
The team watches blood tests, urine output and fluid balance closely, adjusting the machine. Starting to pass more urine can be an early sign the kidneys...
Blood tests after discharge to confirm the kidneys keep recovering.
The team watches blood tests, urine output and fluid balance closely, adjusting the machine. Starting to pass more...
The machine is used less, then paused to see if the kidneys can cope. If they manage, the treatment is stopped and...
The kidneys may work partly at first. Blood tests are repeated to check they keep improving, and medicines and...
Many people's kidney function keeps improving over weeks. Some are left with reduced function and need follow-up...
What is kidney support (dialysis) in intensive care?
The kidneys clean the blood, balance fluids and salts, and make urine. When someone is very ill, the kidneys can suddenly stop working properly — this is called acute kidney injury. If it is severe, waste and extra fluid build up in the body and the kidneys need help.
In intensive care, that help comes from a machine that filters the blood, doing the kidneys' job for a while. You may hear it called dialysis, haemofiltration, or renal replacement therapy. Blood is gently drawn out through a special line, passed through a filter that removes waste and excess fluid, and returned to the body.
In intensive care this is often done slowly and continuously, around the clock, because very ill people cope better with a gentle, steady treatment than a fast one. It is usually a temporary measure to support the body while the cause of the illness is treated.
Important point to hold onto: in many people the kidneys recover and the machine can be stopped. In some, recovery is partial or takes a long time, and a few people need longer-term dialysis. The team will explain how your relative's kidneys are responding as time goes on.
Types, options & approaches
There may be different ways to do this. The right approach depends on the clinical question and your circumstances.
Continuous vs intermittent kidney support
| Feature | Continuous (CRRT) | Intermittent dialysis |
|---|---|---|
| Speed | Slow and steady | Faster, in sessions |
| Best for | Very unstable patients | More stable patients |
| Effect on blood pressure | Gentler | Can cause dips |
| Time on the machine | Around the clock | A few hours at a time |
The team chooses the type that suits how ill and stable the person is, and may switch between them as things change.
Preparing for your treatment
- Kidney support is usually started as an emergency in intensive care, so there is rarely time to prepare.
- Ask the team to explain why the kidneys need help and what the machine is doing.
- Tell staff about any existing kidney problems, the person's usual medicines, and any allergies.
- Mention if the person has expressed views about treatments such as dialysis.
- Choose one family member as the main point of contact for updates.
- Ask whether the kidneys are expected to recover, and what would change the plan.
What happens
A special wider tube (a dialysis line) is placed into a large vein, usually in the neck or groin, under local anaesthetic and using ultrasound to guide it. This line carries blood to and from the filtering machine at the bedside.
The machine draws blood out a little at a time, passes it through a filter that removes waste and extra fluid, and returns it to the body. A medicine is often added to stop the blood clotting in the circuit. Nurses watch the machine closely, checking the blood pressure, fluid balance and blood tests, and adjusting the settings.
The treatment itself is not painful, and the person is usually sedated for their wider intensive care. The machine alarms from time to time as a normal part of its working; this does not necessarily mean something is wrong. The team decides each day whether to continue, pause or change the treatment.
Is this treatment right for me?
A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.
May not be suitable if…
- Where the underlying illness is so severe that organ support cannot lead to recovery, comfort-focused care may be more appropriate.
- If a person with long-term kidney failure has chosen not to have dialysis, that decision is respected.
- When the burdens of treatment clearly outweigh any realistic benefit, the team will discuss this honestly.
- Decisions are made by senior clinicians with the family, taking account of the whole picture, not the kidneys alone.
Delay or rearrange if…
- Kidney support is started promptly when needed, so it is not usually postponed.
- Where someone is improving, the team may wait to see if the kidneys recover before starting, rather than rushing in.
- Timing of starting dialysis is a clinical judgement that balances the risks of treatment against waiting.
- Families should ask for clear information and not feel pressured into quick decisions.
Alternatives to discuss
- Supportive care without dialysis — careful control of fluids, salts and medicines — if the kidney injury is milder.
- Watchful waiting to see if the kidneys recover on their own, where it is safe to wait.
- Comfort-focused care if intensive treatment can no longer help.
- Treating reversible causes, such as dehydration, infection or a blockage, which may improve the kidneys.
Before you decide
Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.
What matters most to me?
Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.
What are all my options?
Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.
What would make me pause?
Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.
What happens if I do nothing today?
For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.
Comfort, sedation or contrast choices
If local anaesthetic, sedation, contrast or pain relief is used, ask what is planned, why, and what it means afterwards.
Benefits
- Removes waste products that build up when the kidneys stop working
- Takes off extra fluid, which can ease breathing and reduce swelling
- Helps keep salts and acids in the blood at safe levels
- Is gentle enough, when run continuously, for very ill and unstable people
- Buys time for the kidneys to rest and, in many people, recover
- Can be stopped once the kidneys start working again
Risks & complications
- Drops in blood pressure during treatment, especially with faster dialysis
- Bruising or bleeding around the dialysis line
- Changes in blood salts that need close monitoring and correction
- Feeling cold, as blood passing through the circuit can cool the body
- Infection entering the bloodstream through the dialysis line
- Clots forming in the line or filter, needing the circuit to be changed
- The line moving or needing to be replaced
- A collapsed lung (pneumothorax) when a neck line is placed, which is uncommon
- Serious bleeding linked to the medicines used to stop clotting
- Lasting kidney damage so that long-term dialysis is needed
- Air entering the line (air embolism), which is rare with modern machines and safeguards
The dialysis line is the main source of avoidable problems — infection, bleeding and, rarely, a collapsed lung when placed in the neck. The bigger question is whether the kidneys will recover, which depends largely on the illness that damaged them. Ask the team how the kidneys are responding and whether long-term dialysis is a possibility.
Published figures to discuss
How likely the kidneys are to recover, and the risks of treatment, depend heavily on the cause of the injury, the person's previous kidney health and how ill they are. Reliable single percentages do not apply to every patient, so the team will give a view based on your relative rather than a fixed figure. Some long-term studies report that a meaningful proportion of people who needed dialysis for severe acute kidney injury recover function, but the range is wide.
| Figure | Reported range | How to interpret it | Source / confidence |
|---|---|---|---|
| Mortality when acute kidney injury requires ICU dialysis | High; many cohorts report hospital mortality around 40 to 60%, depending on illness severity | The dialysis itself supports the kidneys; prognosis depends mainly on sepsis, shock, other organ failures and baseline health. | NHS — Acute kidney injurynhs.ukPublished figure |
| Long-term kidney impairment after ICU dialysis | A minority need ongoing dialysis, but risk is higher with pre-existing kidney disease | Survivors need follow-up kidney blood tests and medication review. | NHS — Acute kidney injurynhs.ukSource-linked context |
| Bleeding or clotting in the dialysis circuit | Common practical issue | Anticoagulation choices balance bleeding risk against filter clotting and inadequate treatment. | NHS — Acute kidney injurynhs.ukSource-linked context |
| Dialysis-line infection, bleeding or pneumothorax | Uncommon but important | The line should be inserted with sterile technique and removed as soon as it is no longer needed. | NHS — Acute kidney injurynhs.ukSource-linked context |
These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.
What happens afterwards
Whether and how fast the kidneys recover depends mostly on what caused the injury and how ill the person is overall. The dialysis machine supports the body, but it is the kidneys themselves that need to heal, which can take days, weeks or sometimes longer.
- A period where the kidneys work only partly before improving further
- Blood tests being repeated often to track recovery
- Tiredness and weakness as part of the wider recovery from critical illness
- Needing the dialysis line in place until the team is sure the kidneys will cope
- Some swelling or fluid changes that settle as the kidneys recover
Aftercare
- Attend kidney follow-up appointments so recovery is checked with blood tests.
- Drink and eat as advised; fluid or diet limits may apply for a time.
- Take medicines as prescribed and tell doctors about the kidney injury before any new medicine or scan with dye.
- Avoid over-the-counter anti-inflammatory painkillers unless a doctor says they are safe.
- Watch for and report signs of infection or reduced urine output.
- Tell the GP about the acute kidney injury so future risks can be reduced.
- Ask what can be done to protect the kidneys in future.
- A follow-up appointment for blood tests to check kidney function
- A clear list of medicines, and which to avoid
- Advice on fluids and diet if any limits apply
- Information on the warning signs of another kidney problem
- A note for the GP that an acute kidney injury occurred
- Contact details for the kidney or intensive care follow-up team
⚠ Get urgent help if…
- Passing little or no urine, or much less than usual
- A high temperature, shivering or feeling very unwell (possible line or blood infection)
- Redness, swelling, pain or oozing around where the dialysis line was
- Increasing breathlessness or swelling of the legs and body
- Unusual drowsiness or confusion
- Bleeding that does not stop from the line site
Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.
General guidance — it doesn't replace the specific advice your specialist gives you.
Results & realistic expectations
A good result means the kidneys recover enough for the machine to be stopped and the body to manage on its own. This usually becomes clear over days to weeks as urine output returns and blood tests improve. The dialysis line is then removed.
Kidney support cannot guarantee that the kidneys will recover. Many people regain full or near-full function, some are left with reduced function, and a small number need long-term dialysis. The team will explain how your relative's kidneys are responding and what it means.
Many people who needed kidney support in intensive care recover their kidney function within weeks, though it can take months. Some are left with reduced function or a higher risk of kidney problems later, and a few need long-term dialysis. Having had an acute kidney injury is worth telling future doctors, as it affects choices about medicines and scans.
Related tests, treatments or support
Kidney support is usually one part of wider intensive care, given alongside breathing or blood-pressure support and treatment of the underlying illness. It is closely tied to careful control of fluids, salts and medicines, and to regular blood tests.
Follow-up & long-term care
After an acute kidney injury, guidelines recommend that kidney function is checked after discharge and that advice is given on avoiding it happening again. People with ongoing kidney problems are usually referred to a kidney (renal) specialist. The hospital and GP should share information so recovery is monitored.
- Periodic blood tests to monitor kidney function
- Review of medicines that can affect the kidneys
- Follow-up with a kidney specialist if function is reduced
- Long-term dialysis arrangements only if the kidneys do not recover
- Advice on protecting the kidneys, including care with dehydration and certain drugs
Repeat, follow-on and what comes next
- The dialysis circuit may need changing if it clots, which is routine, not a setback.
- Treatment may be stopped, then restarted if the kidneys are not yet ready, and this is normal.
- Some people are switched between continuous and intermittent treatment as they become more stable.
- A small number of people need long-term dialysis if the kidneys do not recover, which the team will discuss.
Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.
What good aftercare looks like
- Blood tests after discharge to confirm the kidneys keep recovering.
- Clear advice on medicines to take and to avoid, including anti-inflammatory painkillers.
- A note in the records, and to the GP, that an acute kidney injury occurred.
- Referral to a kidney specialist if function remains reduced.
- Plain advice on protecting the kidneys in future, such as care with dehydration and dye scans.
What affects the cost
Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:
- This treatment is part of NHS intensive care, so families do not usually face a private bill.
- Where any private critical care exists, cost reflects the overall intensive care stay rather than the machine alone.
- Whether continuous or intermittent treatment is used affects nursing time and equipment.
- The length of time kidney support is needed varies from days to weeks.
- Specialist nursing and close monitoring are major parts of the cost of critical care.
- Follow-up with a kidney specialist may form part of later care.
- Confirmation of whether care is NHS or private, and who is responsible for costs
- Who the intensive care and kidney (renal) specialists are
- What happens if the kidneys do not recover and long-term dialysis is needed
- How decisions about treatment will be shared with the family
- Whether kidney follow-up after discharge is included
- How and where blood tests to track recovery will be done
On the NHS? Kidney support in intensive care is part of urgent NHS critical care, given when the kidneys suddenly fail, rather than a private self-pay treatment.
You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.
Consent traps and marketing red flags
These are not small details. They are often where patients lose choice, time to reflect, or realistic expectations.
Consent traps
- Families not having the machine and the dialysis line explained in plain language.
- No discussion of whether the kidneys are expected to recover or whether long-term dialysis is possible.
- Not recording the person's own previously expressed wishes about dialysis.
- Failing to flag the acute kidney injury for future care, affecting choices about drugs and scans.
- Decisions made without giving the family time and clear information.
Marketing red flags
- Any claim that dialysis 'guarantees' the kidneys will recover.
- Private services implying faster or better kidney outcomes than urgent NHS care.
- Downplaying the risks of the dialysis line, such as infection.
- Language that hides how dependent recovery is on the underlying illness.
Choosing a specialist safely
- Check the specialist is on the GMC Specialist Register for this area.
- Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
- You're entitled to time to consider and to have your questions answered before you agree — the specialist who looks after you should explain it, not a salesperson.
- Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
- You're entitled to your total cost in writing — including any follow-up — before you decide.
Questions to ask your medical professional
Take this to your consultation. A good specialist will welcome every one of these.
- Why have my relative's kidneys stopped working, and is the cause being treated?
- Are the kidneys showing any signs of recovering?
- Is the kidney support likely to be temporary, or could long-term dialysis be needed?
- Where is the dialysis line, and what are its risks?
- How will you protect the kidneys and avoid further damage?
- What follow-up will there be once my relative leaves intensive care?
- Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
- Will you be the specialist who carries out my treatment, and who looks after me afterwards?
- What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
- What does a realistic result look like — and what can this treatment not achieve?
- What are my options, including waiting, doing nothing for now, or choosing a different approach?
- Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
- What is the total cost in writing, including any follow-ups, and how much time do I have to decide?
Frequently asked questions
Is dialysis in intensive care the same as long-term dialysis?
Will the kidneys definitely recover?
Is the treatment painful?
Why does the machine keep alarming?
Why is the treatment running all the time rather than in sessions?
Can we arrange this privately?
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How we made this page
Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →
Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.
Sources & standards: NHS — Acute kidney injury NICE — Acute kidney injury: information for the public Faculty of Intensive Care Medicine — What is intensive care? ICUsteps — Intensive care: a guide for patients and relatives
Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.
Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.
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