Central lines (Skin-tunnelled venous catheters)
Central lines
A central line is a long, hollow tube made from silicone rubber. They are also called skin-tunnelled central venous catheters. Examples of some of the makes that are used are Hickman® or Groshong®. The central line is inserted (tunnelled) under the skin of your chest into a vein. The tip of the tube sits in a large vein just above your heart.
The space in the middle of the tube is called the lumen. Sometimes the tube has two or three lumens. At the end of the tube outside the body each lumen has a special cap to which a drip line or syringe can be attached. Sometimes there is also a clamp to keep the tube closed when it is not being used.
What they are used for
A central line can be used to give you treatments such as chemotherapy, antibiotics and intravenous fluids. It can also be used to take samples of your blood for testing. Central lines can also be used to give liquid food into the vein if your digestive system is not able to cope with food for any reason.
You can go home with the central line in and it can be left in for weeks or months. This makes it possible for you to have your treatment without having to have needles frequently put into your veins. This may be very helpful if doctors and nurses find it difficult to get needles into your veins, or if the walls of your veins have been hardened by previous chemotherapy treatment.
How a central line is put in
Your central line will be put in at the hospital by a doctor or specially-trained nurse. It is usually put in under a local anaesthetic, but sometimes a general anaesthetic is used. You should not feel any pain when the tube is being put in, but you may feel a bit sore for a few days afterwards.
First, your chest is cleaned with an antiseptic solution. A small cut is made in the skin near your collarbone and the tip of the tube is threaded into a large vein. This is called the insertion site. The tube is then tunnelled under the skin to reach the exit site. The exit site is the place where the end of the tube comes out of your body (see diagram). You will have a chest x-ray to make sure that the tube is in the right place.
The position of the exit site will vary from person to person. You can ask the person who is going to put the central line in where the exit site is likely to be on your chest.
When the tube has been put in you will have dressings covering the insertion and exit sites. For a few days you may have some pain or discomfort where the tube has been tunnelled under the skin. A mild painkiller such as paracetamol will help to ease this.
What stops the central line falling out?
There is a small 'cuff' around the central line which can be felt under the skin just above the exit site. The tissue under the skin grows around this cuff over a period of about three weeks and holds the line safely in place. Until this has happened you will have a stitch holding the line in place.
Care of your central line
When the central line is not being used there is a small risk that it may become blocked. To stop this happening a small amount of fluid is 'flushed' into the line using a syringe. This is usually done once a week. The exit site will also need to be cleaned once a week to reduce the risk of infection. If you have a dressing on the site it will need to be changed once a week.
The nurses at the hospital may teach you how to do this for yourself if you feel able to, or a district nurse can do it for you at home.
Possible problems
Infection
It is possible for an infection to develop either inside the central line or around the exit site. You should contact your hospital doctor or nurse if:
- the exit site becomes red or swollen or painful
- you notice discoloured fluid coming from it
- you develop a temperature.
You will be given antibiotics but if these do not clear the infection from the line, it may have to be removed.
Clots
It is possible for a blood clot (thrombosis) to form in your vein at the tip of the line. You may be given a tablet of warfarin (an anticoagulant) to take each day to help prevent this. If a clot does form the line may have to be removed. You will also be given some medication to dissolve the clot.
Signs of this are:
Air in the central line No air must be allowed to get into your central line. The clamps should always be closed when the line is not in use. The line must not be left unclamped when the caps are not in place.
Break or cut in the line It is important that you do not get a break or cut in the line. Do not use scissors near the line and only use the clamp on the thicker, strengthened part of the line.
If the line does get cut or split, try to clamp it between the split and the exit site (where it comes out of your body) and call your hospital. The nurses may be able to repair the line, but if this can't be done, the line will be removed.
How the central line is removed
When you no longer need the central line it will be taken out. A doctor or nurse will do this for you, usually in the outpatients department. You will not need to have a general anaesthetic when the central line (catheter) is removed.
You will be asked to lie flat on a bed. Your chest will be cleaned with antiseptic, and the line will be gently but firmly pulled until it loosens and comes free. This does not usually take more than a few minutes, but can be uncomfortable.
If the line has been there a long time, the nurse or doctor may need to do a minor procedure to remove it.
A dressing will be put over the exit site and you will be asked to remain lying down until it is certain that there is no bleeding.
