What you need to know about kidney replacement therapy

Renal disease is a spectrum of abnormal function of the kidneys. It ranges from mild, with minimal and possibly reversible abnormalities, to chronic and permanent dysfunction.

Data from the United States (US) in 2014 indicated that over half a million persons had been diagnosed with the chronic and permanent form of renal disease known as End Stage Renal Disease (ESRD). ESRD costs the medical services in the US over US$2 million a year to treat at a cost of over US$50,000 per patient.

When the kidneys fail completely, replacement therapies are needed to accomplish the natural functions of the kidneys and preserve the patient’s life. These methods include:

- Dialysis
- Haemodialysis
- Peritoneal dialysis
- Transplant

Dialysis is the process by which external devices clear the body of the waste products, which would normally be cleared by the kidneys.

In haemodialysis, the patient’s blood is passed through a machine which clears the waste products and returns the blood to the patient’s body.

In peritoneal dialysis, the internal lining of the abdomen is used as a filter with specialised fluid to accomplish the clearance of the waste products.
 

Haemodialysis is by far the most frequently used treatment therapy (64 per cent).
In order to be able to access the patient’s bloodstream, several methods have been devised.

They include:

- Catheters
- Arteriovenous (artery to vein) connections
- Arteriovenous grafts
- Arteriovenous fistulas (AV fistualas/AVF)

The creation of an access into the patient’s bloodstream is the most critical part of this process, and each type has advantages and disadvantages.

CATHETERS

Catheters are usually the first type of access used for a patient. They involve placing a specialised tube down a large neck vein and into the heart. In this region, the blood flow is fast enough for effective clearance of waste products.

Radiologists play an important role in placing these devices safely, using ultrasound and x-rays to guide the process. The radiologist’s involvement considerably reduces the risk of complications during placement.

Advantages of catheters include:

- They can be placed without admission to hospital
- They can be used immediately
- They can be removed and replaced easily
- No needle sticks are needed to access bloodstream once placed.

Disadvantages of catheters include:

- They are not an ideal for long-term use
- They have high infection rates
- They cause narrowing of veins, making future types of access challenging
 

ARTERIOVENOUS CONNECTIONS

These arteries-to-vein connections are a longer lasting method compared to catheters. Specialist surgeons are capable of making the connections between these vessels. They, however, require a map of the vessel pattern of limbs to be able to carry out the procedure effectively. This map is provided by the radiologist, who provides detailed measurements of all the vessels of the limbs. This helps in selecting the vessels most suitable for the process.

GRAFTS:

Advantages of grafts include:

- They can be placed easily
- They work predictably
- They can be used early after placement
- They can be easily converted to fistulas

Disadvantages of grafts include:

- They easily develop clots
- They are prone to infection
- They can only be used for a limited amount of time

FISTULAS

Advantages of fistulas include:

- They are the most effective type of access
- They are the access least prone to infection
- They can be used for years
- They have the fastest blood flow and therefore clean the blood the fastest

Disadvantages of fistulas:

- The fistula is visible under the skin
- One must wait several weeks before it can be used (mature)
- Grafts or catheters are needed while the fistula matures
- It can fail to mature

In summary, there are many options now available for patients with renal failure needing kidney replacement therapy. The radiologist plays a very important role in assisting your doctor in providing safe and effective treatment options.

- Dr Mellanie Didier is a consultant radiologist and member of the Jamaica Association of Radiologists.