(ONE PHOTO OF PATIENT UNDERGOING DIALYSIS)
This form of dialysis removes waste products from the blood by passing it out of the body, through a filtering system (dialyser) and returning it, cleaned, to the body.
While in the filtering system, the blood flows through tubes made of a membrane that allows the waste products (which are much smaller than blood cells) to pass out through it.
The waste products pass through the membrane into a dialysis solution (dialysate), then out of the machine. The “clean” blood is carried on through and returned safely to the body.
This happens over and over again throughout the dialysis session. Each time the “clean” blood is returned to the body, it picks up more waste products from the cells it circulates through, and brings these newly-collected toxins back to the dialyser to be removed.
Fresh dialysate is passed through continuously, to make the rate of the cleaning process as fast as possible.
As well as cleaning the blood, the dialysis machine also removes excess water. This part of the process is called ultrafiltration which can be done separately without dialysis.
It takes about 4 hours (perhaps more) to complete a good session of haemodialysis, which needs to be done 3 times a week.
When you have to undergo Haemodialysis, you have to construct access. There are two common forms of access:
- 1. haemocath
- AV (arterio-venous) fistula,
- This is a narrow tube which is inserted into the vein between the shoulder and the neck.
- The tube is closed off when not in use, with a short length of double tube – for taking and returning blood – left outside of the skin.
- With this kind of access, you don’t have to wait several weeks for the vein to thicken (like you do with a fistula), so it can be used when a patient needs to start dialysis right away. It is often used on a temporary basis, until a fistula has been established.
AV (arterio-venous) fistula
- Created surgically at least six weeks before haemodialysis begins. It is done under general anaesthetic.
- Creating a fistula involves joining a vein to an artery, usually in the upper arm or wrist, to form a bigger, stronger blood vessel. This makes it easier to insert the needles that are required to withdraw blood and then return it to the body.
- Patients who have a fistula can usually feel it “buzzing” slightly. This is a good sign – it means that it’s working well. If it stops buzzing, you should let your Renal Unit know, as this may be an indication that the blood has clotted.
- Some people have more of a problem with clotting than others, and have difficulty keeping their fistula open. These patients may be given an artificial fistula, in which a tube is sewn in place to join the artery and vein.
- Once a fistula is established, it is likely to cause few problems. In some cases, however, a fistula may be created too big or too small, and will need to be corrected.
- Sometimes the surgeon will have to make a graft using a vein or a piece of artificial blood vessel because it is not possible to make a fistula.
Some patients have the option of doing home haemodialysis, with a dialysis machine at home. Whether you qualify will depend on whether you are medically suitable and, possibly, on whether or not you live with someone who can support you and deal with any emergencies.
In addition, you will need a home that has space for accommodating not only the machine, but the supplies – disposable lines, fluids, drugs, etc – that go with it (the supplies will be delivered regularly from your Renal Unit). If your home is too small, it is worth discussing this problem with your Renal Social Worker.
Some alterations to your plumbing and electricity supply may also be needed. And you will certainly need to have a telephone.
If you wish to do home haemodialysis, you will need comprehensive training in order to become confident and self-reliant. The length of training varies, depending on the individual – it could be from 6 to 16 weeks or longer. And for the first weeks of home haemodialysis, a member of your Renal Unit staff will be with you when you dialyse.
Dialysing at home brings the benefits of increased independence from your Renal Unit and choice about how you schedule your sessions.
On the down side, however, it can put a strain on the people you live with. It also involves time preparing the machine for each session (unlike in your Renal Unit, where the machine is ready for use when you arrive).