Patient Information for Continuous Renal Replacement Therapy (CRRT)
What is continuous renal replacement therapy (CRRT)?
- Dialysis is a treatment in which blood is withdrawn from the body and passed through a dialysis machine. The blood flows through a filter that removes waste products, toxins, and excess fluid before being returned to the patient. Different types of dialysis machines are used in clinical practice, but they operate on the same basic principle.
- Continuous renal replacement therapy (CRRT), also known as continuous dialysis, is a special type of dialysis used for critically ill patients in the intensive care unit. These patients often have kidney failure together with unstable hemodynamic or cardiovascular conditions, making intermittent hemodialysis unsuitable. CRRT may also be used in some patients without kidney disease when certain toxins need to be removed from the body.
- Intermittent hemodialysis (IHD) is a dialysis treatment performed periodically at healthcare facilities. Patients may be discharged on the same day if their condition is stable. IHD is commonly used for patients with end-stage chronic kidney disease, usually 2–3 times per week, with each session lasting approximately 3–4 hours. IHD may also be performed in hospital for patients with acute kidney injury who are hemodynamically stable.
- CRRT is less likely to cause low blood pressure than IHD. It is performed continuously for more than 12 hours, usually 20–24 hours per day, and may continue for several consecutive days to continuously remove waste products and excess fluid from the body. Anticoagulant medication is usually required during CRRT to prevent blood clotting within the filter.
Who may need continuous renal replacement therapy?
- Approximately 5% of hospitalized patients develop acute kidney injury (AKI) or acute kidney failure. Among critically ill patients treated in the intensive care unit, the incidence of AKI is approximately 40–60%. Many factors can contribute to AKI in critically ill patients, including shock or low blood pressure, infection, medications, and toxic substances.
- Approximately 25% of intensive care patients with AKI may require dialysis. CRRT is often the preferred form of dialysis for these critically ill patients, particularly when they are hemodynamically unstable or require vasopressors to maintain blood pressure.
- Some patients with normal kidney function may also require CRRT to remove toxins from the body in certain conditions, such as severe acute pancreatitis with multiple organ dysfunction, poisoning, critical COVID-19, or medication-related metabolic acidosis.
How is continuous renal replacement therapy performed?
- After determining that CRRT is indicated, the doctor will explain the reason for treatment and the possible risks or complications associated with CRRT to the patient and their family.
- The patient or their legal representative will receive counseling and be asked to sign an informed consent form.
- The doctor will insert a large intravenous catheter, commonly called a dialysis catheter, into a major vein, usually in the groin or neck, to allow blood to be withdrawn from the body. The catheter is then connected to the dialysis machine through a tubing system.
- The patient’s blood travels through the tubing to the dialysis machine and passes through a filter, where toxins and excess fluid are removed. The filtered blood is then returned to the patient through the same dialysis system.
- CRRT is usually performed for 20–24 hours per day and may continue for several days until the patient’s kidney function begins to recover.
- A CRRT filter can generally be used for approximately 24–36 hours before replacement is required. However, in some conditions, the filter may clot more quickly and last only 8–18 hours, requiring more frequent replacement.
How long does a patient need continuous renal replacement therapy?
CRRT is continued until the patient begins to show signs of kidney recovery or until their blood pressure becomes more stable and they can be transitioned to intermittent hemodialysis (IHD).
What are the signs that the kidneys are recovering?
- One of the earliest signs of kidney recovery is that the patient begins to produce urine again. Most patients requiring CRRT have anuria or oliguria, meaning little or no urine output. However, even when urine production resumes, the kidneys may still need more time to recover their ability to filter dissolved substances and remove waste products. It may take several weeks or months for kidney filtration to recover.
- Recovery of kidney function after acute kidney injury may take several months or longer. If the patient had normal kidney function before hospitalization, is relatively young, and has no significant underlying medical conditions, the likelihood of kidney function recovery may be greater than 90%.
What complications may be associated with continuous renal replacement therapy?
CRRT may be associated with several complications, including:
- Low blood pressure. Hypotension occurs less frequently with CRRT than with intermittent hemodialysis.
- Hypothermia.
- Coagulation disorders or abnormal bleeding related to the use of anticoagulant medication.
- Increased risk of infection related to the dialysis catheter.
- Complications related to catheter insertion, such as accidental arterial puncture, bleeding, or venous thrombosis.
- Discomfort caused by prolonged restriction of movement in the leg where the dialysis catheter is placed.
- Increased risk of pressure ulcers because of reduced mobility and limitations in repositioning during dialysis.
“The information provided above is for reference purposes only and is not intended as medical advice or a recommendation. Please consult your doctor for detailed guidance.”