Overview

Continuous renal replacement therapy (CRRT) is an available kidney replacement method that involves intermittent hemodialysis and peritoneal dialysis. It is a continuous, slow dialysis for 24 hours or more, allowing fluid homeostasis and solute. A pump-driven venovenous extracorporeal cardiopulmonary circuit performs CRRT with blood purification as renal support.

CRRT is a slow and gentle form of dialysis that removes excess fluids and waste products from the blood in a continuous manner, similar to the way the kidneys function in healthy individuals. This article will help you know about procedures, indications, complications, and other important topics.

Continuous Replacement Therapy Indication

Indications for renal replacement often include indications for dialysis in acute renal failures, such as volume overload, electrolyte disturbances (including hyperkalemia), acidosis, and uremic complications. The difference lies in the decision regarding the renal replacement method. The most common indication for choosing CRRT is in hemodynamically unstable patients(or patients with unstable blood pressure or heart rate), often in intensive care units. Due to the slower rate of fluid elimination, CRRT is theoretically less hypotensive than others. A second advantage for these patients is that they often require extensive fluid management, including medications and parenteral nutrition, and CRRT prevents a state of overload.

CRRT is used when kidney function is not in homeostasis. This includes the following conditions:

Acute kidney failure
Chronic renal failure
Myasthenia gravis
Septic shock
Chronic failure with acute liver failure

Hemofiltration (HF) and hemodialysis (HD) are two common techniques used in continuous renal replacement therapy (CRRT) for treating acute kidney injury (AKI) in critically ill patients.

Hemofiltration (HF) is a convective clearance technique that removes larger molecules. Hemodialysis (HD), on the other hand, is a diffusive clearance technique that removes smaller solutes.

In CRRT, both HF and HD can be used alone or in combination to provide effective clearance of solutes from the blood. It's important to note that HF and HD are complementary therapies in CRRT, as they each have strengths and weaknesses.

Different types of Continuous Renal Replacement Therapy

Continuous renal replacement therapy (CRRT) is used in critically ill patients with acute kidney injury or other forms of kidney failure. Several different types of CRRT can be used, including:

Continuous Venovenous Hemofiltration (CVVH): In this technique, a large ultrafiltrate volume is passed across a convention or high-permeability membrane.
Continuous Venovenous Hemodialysis (CVVHD): In this technique, blood is passed through a filter, and waste products are removed through diffusion. Replacement fluid is then infused to replace the removed fluid.
Continuous Venovenous Hemodiafiltration (CVVHDF): In this technique, diffusive clearance removes solutes and toxins from the patient’s circulation. It combines convection and diffusion to remove fluid and solids through an efficient hemodiafilter.
Slow Continuous Ultrafiltration (SCUF): This technique involves the removal of excess fluid from the body through ultrafiltration without the addition of replacement fluid.
Continuous Arteriovenous Hemofiltration (CAVH): In this technique, blood is removed from an artery and passed through a filter before being returned to a vein. Fluid is removed through a combination of diffusion and convection. Replacement fluid may be given, but only sometimes.
Continuous Arteriovenous Hemodialysis (CAVHD): In this technique, blood is removed from an artery and passed through a filter, where waste products are removed through diffusion. Replacement fluid may be given, but only sometimes.
Continuous Arteriovenous Hemodiafiltration (CAVHDF): In this technique, blood is removed from an artery and passed through a filter. The fluid component and waste products are removed through a combination of diffusion and convection. Replacement fluid may be given, but only sometimes.

Procedure

Before CRRT

The placement of the dialysis catheter (CVC) is a sterile procedure. This is performed by an intensive care unit (ICU) doctor or radiologist trained in catheter placement.

During CRRT

Here are some of the key steps involved in a typical CRRT procedure:

First, the patient is connected to the CRRT machine, which includes a pump, filter, and tubing.
Blood is drawn from the patient through a catheter, usually inserted into a large vein in the neck or groin.
The blood is then passed through the filter, where waste products and excess fluids are removed.
Replacement fluid, such as saline or a specialised electrolyte solution, is added to the filtered blood to maintain the proper balance of fluids and electrolytes.
The treated blood goes to the patient through another catheter, usually inserted into a vein in the opposite arm.
The CRRT machine monitors the patient's blood pressure, temperature, and other vital signs to ensure the procedure is safe and effective.
The procedure may last several hours or even days, depending on the patient's condition and the specific type of CRRT used.

Throughout the procedure, healthcare providers carefully monitor the patient for any signs of complications or side effects, such as bleeding, infection, or electrolyte imbalances.

After CRRT

As the patient improves, the team may try to stop the CRRT. First, it's to see if his kidneys are working well. If kidney support is still needed, start the ERRC again or switch to hemodialysis. This is done quickly (3-5 days a week).

What is the difference between CRRT and dialysis?

In hemodialysis, waste filtration is done quickly and completed in a few hours. But in CRRT, due to technical differences from routine hemodialysis, it happens slowly, can be performed continuously around the clock, and results in more stable blood pressure during the procedure.

Complications of Continuous Renal Replacement Therapy

The main Complications of CRRT are related to the following:

Catheter-related complications
blood loss,
disconnection,
infection or access failure
Mechanical complications of cardiopulmonary bypass
Fluctuations in salt balance
Hemodialysis related complications
Hypotension
Accidental removal of tubes, including connection to a ventilator, dialysis catheter, or breathing tube Infection
Coagulopathy
venous thrombosis

Specific complications of peritoneal dialysis include:

Peritonitis
Catheter-related infection
Hyperglycemia
Protein loss

You can also get in touch with the expert doctors at Narayana Healthcare based in your city to get immediate attention and medical support during injuries, health disorders or any other health concern.

When to Consult a Doctor

Get in touch with the expert Nephrology doctors at Narayana Healthcare based in your city to get immediate attention and medical support during injuries, health disorders or any other health concern.

Conclusion

CRRT procedure is a safe and effective procedure for acute kidney injury patients. CRRT is preferred over other forms of dialysis in certain situations, such as for patients with hemodynamic instability or those who require precise control over fluid and electrolyte balance.

References

https://www.news-medical.net/health/Renal-Replacement-Therapy.aspx
https://www.ncbi.nlm.nih.gov/books/NBK556028/
https://www.gvh.org/what-is-continuous-renal-replacement-therapy-crrt/