Kidney dialysis, also known as renal replacement therapy (RRT), is needed during acute kidney injury (AKI) when the kidneys are no longer able to maintain life-sustaining functions and medical treatments have failed. In the UK, dialysis for AKI is typically a temporary measure used to bridge the gap while the kidney tissue repairs itself. It is reserved for the most severe cases usually Stage 3 AKI where the build-up of toxins, acids, or fluids poses an immediate threat to the heart or lungs.
In the NHS, the decision to start dialysis is guided by a specific set of clinical criteria often remembered by the acronym ‘AEIOU’. Most patients with AKI do not require dialysis and recover with intravenous fluids and medication reviews; however, for approximately 1% to 5% of hospitalised AKI patients, dialysis becomes an essential, life-saving intervention. In this article, you will learn about the emergency triggers for dialysis, how the procedure works in an acute setting, and the clinical evidence supporting its use in the UK.
What We Will cover in This Article
- The ‘AEIOU’ clinical criteria used to determine the need for dialysis
- How dialysis prevents life-threatening complications like hyperkalaemia
- The difference between emergency dialysis and long-term chronic dialysis
- Identifying signs of fluid overload that require mechanical filtration
- What to expect during an acute dialysis session in a hospital setting
- The role of specialist renal teams in managing RRT in the NHS
- Clinical evidence regarding the timing and outcomes of dialysis in AKI
The ‘AEIOU’ Criteria for Emergency Dialysis
Clinical teams in the UK use a standardised checklist to decide when a patient’s kidney function has dropped to a dangerous level. While a high creatinine level is a sign of injury, it is the systemic symptoms the ‘AEIOU’ that usually trigger the need for dialysis.
If a patient meets any of these criteria and does not respond to initial medical treatments (such as diuretics or potassium-shifting medications), an urgent referral to a nephrologist is made.
The ‘AEIOU’ Checklist:
- A (Acidosis): Severe acidity in the blood (metabolic acidosis) that cannot be corrected with medication.
- E (Electrolytes): Life-threateningly high potassium (hyperkalaemia) that risks stopping the heart.
- I (Intoxication): Overdose of certain toxins or medications that the kidneys cannot clear.
- O (Overload): Severe fluid build-up in the lungs (pulmonary oedema) that makes breathing difficult.
- U (Uraemia): High levels of urea causing inflammation of the heart lining (pericarditis) or brain dysfunction (encephalopathy).
How Dialysis Works in Acute Kidney Injury
In an acute hospital setting, dialysis is performed using a machine that acts as an artificial kidney. Blood is taken from the body through a temporary tube called a ‘vascath’ (usually placed in a large vein in the neck or groin), passed through a filter to remove toxins and excess water, and then returned to the patient.
There are two main types used in the UK for AKI. For patients who are relatively stable, Intermittent Haemodialysis (IHD) is used for a few hours at a time. For those who are critically ill in an Intensive Care Unit (ICU), Continuous Renal Replacement Therapy (CRRT) is used 24 hours a day to gently filter the blood without dropping the patient’s blood pressure too quickly.
| Feature | Intermittent Haemodialysis (IHD) | Continuous Therapy (CRRT) |
| Duration | 3 to 4 hours per session | 24 hours a day |
| Clinical Setting | Renal ward or stable acute ward | Intensive Care Unit (ICU) |
| Primary Goal | Rapid removal of toxins and fluid | Gentle, steady filtration for unstable patients |
| Recovery Sign | Increasing urine output between sessions | Gradual improvement in blood chemistry |
Temporary vs. Permanent Dialysis
It is a common fear that needing dialysis during AKI means needing it for life. In the UK, the majority of patients who require dialysis for AKI eventually regain enough kidney function to stop the treatment. The dialysis is a ‘supportive’ therapy it does the work of the kidneys to keep the patient safe while the underlying cause (like sepsis or a blockage) is treated.
Clinicians monitor ‘renal recovery’ by looking for an increase in urine output and a steady drop in blood creatinine levels. Once the kidneys can manage the body’s chemistry independently, the dialysis is tapered off and the temporary tube is removed.
To Summarise
Kidney dialysis is needed during AKI as a life-saving measure when the kidneys can no longer manage blood acidity, dangerous potassium levels, or severe fluid overload. Using the ‘AEIOU’ criteria, NHS specialist teams identify when medical treatments are insufficient and mechanical filtration is required. While it is a serious intervention, dialysis in the context of AKI is often temporary, providing the necessary support to keep the body stable until the kidneys repair themselves and resume their normal function.
If you experience severe, sudden, or worsening symptoms, call 999 immediately.
Does needing dialysis mean my kidneys are failed forever?
No; in the context of AKI, dialysis is usually a temporary ‘bridge’ to allow your kidneys time to heal from an acute illness or injury.
Is the procedure painful?
The insertion of the temporary tube is done under local anaesthetic; the dialysis process itself is generally painless, though you may feel tired or cold during the session.
How many times will I need dialysis?
This varies; some patients only need one or two sessions, while others may need it for several weeks until their urine output improves.
Why do I need a tube in my neck?
For AKI, doctors use a ‘vascath’ in a large vein because it provides the high blood flow needed for the machine to work effectively and can be inserted quickly in an emergency.
What happens if I don’t have dialysis when it’s recommended?
If the ‘AEIOU’ triggers are met, not having dialysis can lead to life-threatening complications like cardiac arrest from high potassium or respiratory failure from fluid in the lungs.
Can I eat and drink while on dialysis for AKI?
Your clinical team will give you specific advice; usually, you will have a restricted fluid allowance to prevent your body from becoming overloaded between sessions.
Authority Snapshot
This article was written by Dr. Rebecca Fernandez, a UK-trained physician with an MBBS and extensive experience in internal medicine, cardiology, and intensive care. It was reviewed by the MyPatientAdvice clinical team to ensure it follows the latest NHS and NICE [NG148] guidelines on the initiation of renal replacement therapy. Our goal is to provide the public with clear, factual, and medically safe information to help them understand the critical role of dialysis in acute kidney care.
