Aspiration à l'aiguille transbronchique guidée par échographie endobronchique

What is EBUS TBNA?

Endobronchial ultrasound-guided transbronchial needle aspiration is a special technique used to take samples of body tissue from inside the chest. It is also known as EBUS TBNA for short. The procedure is carried out using a special kind of bronchoscope. This is a thin flexible kind of 'telescope' which passes through the mouth and into the airways. The bronchoscope (often shortened to 'scope') allows doctors to see inside the lungs and carry out the procedure.

Endobronchial means from inside or within the bronchus. The bronchi (the plural of bronchus) are large tube-like airways. They take air from the windpipe (trachea) to the smaller airways, called the bronchioles. During the procedure ultrasound is used to help the doctor doing the test see the structures just outside the airways. This gives the test the first part of its name. The scope also contains a very fine needle. This needle is used to take samples of body tissue by pushing through the bronchus to the tissue on the other side. The needle holds the sample of tissue; this is called aspiration. Transbronchial means across the bronchus, giving the name transbronchial needle aspiration.

What is EBUS TBNA used for?

Endobronchial ultrasound-guided transbronchial needle aspiration allows doctors to take samples of tissue without having to do an operation. It is used to take tissue samples from an area of the body called the mediastinum. The mediastinum is part of the chest and contains the heart, thymus, gullet (oesophagus), windpipe (trachea) and various nerves and lymph nodes. This area of the body is normally very difficult to reach, which is why EBUS TBNA is such a useful procedure.

It may be used to:

• Investigate enlarged lymph nodes in the mediastinum.

• Diagnose conditions such as sarcïdose ou la tuberculose.

• Diagnose cancer outside the bronchi.

• 'Stage' cancer by taking tissue samples from the lymph nodes.

Your doctor should tell you why the procedure is being done.

EBUS TBNA and cancer staging

One of the main uses for EBUS TBNA is in the staging of cancer. The stage of a cancer is a measure of how much the cancer has grown and spread. Depending on the type of cancer, there may be several different tests used to 'stage' the cancer. By accurately determining the stage, doctors can decide which treatment may be best and give a better idea of what might happen next. One of the ways doctors assess the stage of a cancer is to see if it has spread to structures called lymph nodes.

Lymph nodes are part of the lymphatic system. This is a network of channels and vessels that carry a fluid called lymph. Lymph nodes act like a filter for lymph. They contain white blood cells which can recognise germs (bacteria and pathogens) which have entered the lymph via the bloodstream. When foreign material is detected, other dedicated immune cells are recruited to the node to deal with the infection. This is why lymph nodes may become swollen when you have an infection. Lymph nodes can also become swollen in some forms of cancer. Cancer cells can break off from the main tumour and enter the lymph. These cells may then collect in the lymph nodes. By checking the lymph nodes for signs of cancerous cells, doctors can see if cancer has spread within the body. See the separate leaflet called Stages of cancer for more details.

How does EBUS TBNA work?

By using the flexible scope doctors can gain access to the airways of the lungs. The scope has a special ultrasound probe on the end. This provides ultrasound images that are transmitted to a TV monitor for the doctor to see.

Ultrasound is a high-frequency sound that you cannot hear but it can be emitted and detected by the probe on the end of the scope. Ultrasound travels freely through fluid and soft tissues. However, ultrasound is reflected back (it bounces back as 'echoes') when it hits a more solid (dense) surface. For example, the ultrasound will travel freely though blood in a heart chamber. However, when it hits a solid valve, a lot of the ultrasound echoes back.

Ainsi, lorsque l'échographie 'frappe' différentes structures de densité différente dans le corps, elle renvoie des échos de force variable.

The probe is connected to the ultrasound machine and monitor. Pulses of ultrasound are sent from the probe into your body. The ultrasound waves then 'bounce back' (echo) from the various structures surrounding the bronchus.

The echoes are detected by the probe and are sent to the ultrasound machine. They are displayed as a picture on the monitor. The picture is constantly updated so the scan can show movement as well as structure.

In effect, the ultrasound allows the doctor to see through the airways by showing what is on the other side. This allows the doctor to find the lymph node or tissue they want to sample. Then they can use the needle to take a sample of that tissue, while avoiding other structures such as blood vessels. This makes EBUS TBNA an extremely useful method of taking samples from tissue just outside the airways.

What happens during an EBUS TBNA?

This is usually done as an outpatient or day case. Some hospitals may do the procedure under general anaesthetic; the following is a description of the outpatient procedure. The doctor will usually numb the back of your throat by spraying on some local anaesthetic. This may taste a bit unpleasant. Also, you will be given a sedative to help you to relax. This is usually given by an injection into a vein in the back of your hand. The sedative can make you drowsy but it is not a general anaesthetic and does not 'put you to sleep'. However, you are unlikely to remember anything about the procedure if you have a sedative. You may also receive some pain relief into the back of your hand to make you more comfortable.

You may be connected to a monitor to check your heart rate and blood pressure during the procedure. A device called a pulse oximeter may also be put on a finger. This does not hurt. It checks the oxygen content of the blood and will indicate if you need extra oxygen during the EBUS TBNA. You may have a soft plastic tube placed just inside your nostril to give you oxygen during the procedure.

The doctor will insert the tip of the scope into your mouth and then gently guide it around the back of your throat into your windpipe (trachea). The scope transmits pictures through a camera attachment on to a TV monitor for the doctor to look at. The bronchoscope may make you cough.

Once the scope is in position, the doctor uses the ultrasound pictures to take the samples of tissue (called biopsy samples). This is painless. The biopsy samples are sent to the laboratory for testing and to look at under the microscope. The bronchoscope is then gently pulled out. The procedure itself usually takes about 30 minutes. However, it may take up to four hours for the whole appointment - to prepare, give time for the sedative to work, for the EBUS TBNA itself and to recover.

What should I do to prepare for an EBUS TBNA?

Your hospital will give you specific information about what you need to do to prepare for the EBUS TBNA. You may have a blood test, done shortly before the procedure, to check how well your blood will clot. This is to make sure that you are not likely to bleed following the procedure. You may be advised not to take any medicines that affect blood clotting, such as aspirin and warfarin, for one week before the test. It is important that you let your doctor know what medications you are taking and why you take them.

In addition to this, you should receive instructions from the hospital before the test. These usually include:

• That you should not eat or drink for several hours before the procedure. (Small sips of water may be allowed up to two hours before the test.)

• That you will need somebody to accompany you home, as you will be drowsy with the sedative.

What can I expect after an EBUS TBNA?

After you have the sedative you may take an hour or so before you are ready to go home after the procedure has finished. The sedative will normally make you feel quite pleasant and relaxed. However, you should not drive, operate machinery or drink alcohol for 24 hours after having the sedative. You should not eat or drink anything for two hours after the bronchoscopy because your throat will still be numb. You will need somebody to accompany you home and to stay with you for 24 hours until the effects have fully worn off. Most people feel able to resume normal activities after 24 hours.

Are there any side-effects or complications from an EBUS TBNA?

Most are done without any problem. Your throat may be a little sore for a day or so afterwards. You may feel tired or sleepy for several hours, caused by the sedative. You may also cough up a little blood for a couple of days following the test. You should consult your GP if:

• You have chest pain that doesn't settle after a couple of days.

• You continue to cough up blood.

EBUS TBNA is considered to be a very safe test. Very rarely, an EBUS TBNA can cause damage to the lung. This can sometimes allow air to enter the mediastinum or even more infrequently 'collapse' a lung. It is also possible, although very uncommon, for the procedure to cause an infection or bleeding in the lung. Your doctor should explain the usual risks and possible side-effects before carrying out the procedure.