The kidneys perform the vital function of removing waste products from the blood stream and excreting them through the body’s urinary system. However, if the kidneys should fail, this process would cease and the patient would die unless they could receive a donor kidney or be treated with dialysis, a process which removes the toxins artificially. The mechanism by which kidney dialysis works has been discussed in another article on BrightHub.
A patient whose kidneys have failed typically requires three sessions of treatment per week to remove toxins from their bloodstream. In order for this to happen, the patient needs to be connected to the dialysis machine such that their blood can flow through it, become cleaned and return to their body. Since this treatment becomes a regular feature of the patient’s life, steps are usually taken to make this as simple as possible by providing an easy access point to the patient’s bloodstream by facilitating permanent access to the bloodstream. Dialysis deaths related to catheter usage can occur due to infection. This article will look at the three common alternatives that are available to patients in need of regular dialysis.
The purpose of vascular access, as it is called, is to facilitate access to continuous, high volumes of blood flow which flow from the patient to the dialysis machine and are then returned to the patient.
There are three alternatives which can be used to obtain vascular access: an arteriovenous fistula (AVF); an arteriovenous graft (AVG); or a venous catheter.
In AVF, a fistula (or connection between two parts of the body that are normally separate) is created surgically (under local anaesthesia), usually connecting a vein to an artery in the patient’s forearm. An AVF is useful since the vein involved grows larger and stronger, permitting easier and more reliable access for a line connecting the patient to the dialysis machine. It is considered as the best choice for long-term vascular access; however it can take some time to develop after the surgery – in extreme cases, up to two years.
If AVF is not possible (perhaps because the patient has small veins), an alternative is AVG in which surgeons graft a synthetic tube in place between the artery and the vein. AVG provides vascular access within a few weeks of the operation. Grafts have the advantage of speed over AVF, but may suffer from clotting problems and infections and have a shorter useful lifetime than AVF.
The easiest method for obtaining vascular access is by use of a catheter (a catheter is simply a hollow tube that can be inserted into a vein to allow blood to flow out or drugs to be administered). Catheterisation is used if the disease is detected at an advanced stage or progresses so rapidly that there is no time for AVF or AVG access to be established. The catheter used for hemodialysis has two chambers and permits flow of blood from the body to the dialyser and back again. They tend to be used as a temporary measure for up to a few months until a better alternative can be established. If long-term catheterisation (>3 weeks) is needed, the catheter is usually “tunnelled” under the skin for greater patient comfort.
Unfortunately, there have been dialysis deaths related to catheter usage. This can happen because catheters are prone to clogging and can become infected; a dangerous situation for somebody with a compromised renal system. If a blood clot breaks away, it could result in thrombosis or stroke.
According to the US Renal Data System report, catheters are involved in between 48 and 73% of all end stage renal failure bacteraemia (or septicemias). Statistics show that the morbidity amongst non-diabetic individuals on haemodialysis is greatest for patients using catheters. It is believed to account for between 2750 and 5500 deaths each year (to put these figures into perspective, more than 500 000 Americans were receiving end stage renal failure care in 2007).
- Vascular Access For Hemodialysis: https://kidney.niddk.nih.gov/kudiseases/pubs/vascularaccess/
- Advanced Renal Education Program: https://www.advancedrenaleducation.com/Hemodialysis/AccessComplications/CatheterRelatedBacteremia/tabid/608/Default.aspx