What is CRRT?

Continuous Renal Replacement Therapy (CRRT) is a form of dialysis that runs slowly and continuously, around the clock, rather than in the sharp three- to four-hour sessions of conventional haemodialysis. It clears toxins, excess fluid and dangerous levels of potassium and acid from the blood at a gentle pace that a very sick liver patient can tolerate. Because the fluid shifts are gradual, CRRT is far less likely to drop the blood pressure or raise pressure inside the brain, two problems that matter enormously in liver failure.

Who needs it?

CRRT is an intensive-care treatment. In a hepatology practice it is used mainly for patients whose kidneys fail alongside their liver, including:

Acute-on-chronic liver failure (ACLF) with acute kidney injury that does not recover with fluids, albumin and vasoconstrictor drugs.
Hepatorenal syndrome (HRS-AKI) that has not responded to terlipressin (or noradrenaline) plus albumin – CRRT can bridge the patient to recovery or to liver transplant.
Acute liver failure with kidney failure, high blood ammonia, or brain swelling. CRRT lowers ammonia and helps control fluid and metabolic balance while the team decides on transplant.
Patients who are too unstable – low blood pressure, on ventilator support, on vasopressors – to tolerate standard dialysis.

CRRT does not cure the liver. It buys time and keeps the internal environment stable so the liver can recover, or so the patient can safely reach transplant.

How it is done

A soft double-lumen catheter is placed into a large vein, usually in the neck or groin. Blood is drawn out, passed through a filter that does the work of the kidney, and returned – a small amount of blood is outside the body at any moment. The circuit needs an anticoagulant to stop it clotting; in liver patients, who are already prone to bleeding, we often use regional citrate anticoagulation, which thins the blood only inside the machine and not inside the patient. The therapy runs continuously for days and is adjusted hour by hour by the intensive-care and nephrology teams.

Dr Kalal’s role

CRRT is delivered by the critical-care and nephrology teams; the machine itself is run by trained ICU nurses and intensivists. As the hepatologist, Dr Kalal’s job is to decide when a liver patient needs it, to distinguish reversible hepatorenal syndrome from established kidney damage, to manage the liver disease and its complications in parallel, and to keep the transplant question in view. In severe ACLF and acute liver failure this is genuinely multidisciplinary work – hepatology, critical care, nephrology and transplant surgery around one bed.

Risks

The main risks come from the catheter (bleeding, infection, clot), from the continuous anticoagulation, and from shifts in salts and minerals if the prescription is not carefully monitored. Citrate can accumulate when the liver is very sick, so calcium and acid-base status are checked closely. These risks are manageable in an experienced ICU, and for a patient who genuinely needs CRRT the alternative – uncontrolled kidney failure – is worse.

Where it fits

Think of CRRT as one part of the organ-support package for the sickest liver patients, alongside plasma exchange, ventilation and vasopressor support. It is a bridge, not a destination. For many patients with ACLF and hepatorenal failure, the definitive answer is liver transplantation, and CRRT is what keeps them safe until that decision is made.