Airway endoscopy

 

The parts of the airway

Our “airways” are the air passages which run from the mouth and nostrils, the nasal passages, down the throat (pharynx), the voice box (larynx), the windpipe (trachea) and its left and right divisions (bronchi), then via many more smaller and smaller divisions to the microscopic air spaces in the lungs. Here, oxygen is taken into the blood and carbon dioxide is released from the blood to be breathed out. In all, there are about 23 smaller and smaller divisions from the trachea to the lungs, like tributaries of a river. Remarkably, if all the air spaces of our two lungs were spread out, they would cover the area of a tennis court.

The airways are made up of a framework of cartilage and muscle tubes, lined by mucus-producing cells which keep the airways open, moist and healthy. The mucus is propelled along the airways to be coughed out and swallowed, taking any debris and bacteria with it, and away from the lungs, which are very delicate.

Problems with different parts of the airways can lead to different symptoms, such as snoring, noisy breathing, coughing and breathlessness. In some cases, we need to examine the internal parts of the airways in more detail, using special telescopes to look inside: endoscopes.

Types of airway endoscope

The endoscopes for examining airways can be flexible (bendy, like a noodle) or rigid (stiff, like a pencil) and different types of endoscope are used for different areas. The endoscopes also come in different widths and lengths, depending on the age of the patient.

Airway endoscopy in clinic with local anaesthetic

In patients with upper airway issues (problems with the nose, throat or voice box), we can often gain a great deal of information by endoscopy in clinic. Most often we use thin, flexible endoscopes, between 2-3mm diameter (like a piece of spaghetti or an udon noodle). After spraying the nose carefully with local anaesthetic spray with decongestant- which numbs and opens up the calibre of the nose- we pass the endoscope very gently into the nose, slowly to the back of the nose and into the throat. This allows an excellent view of the throat, base of the tongue and the voice box (larynx).

This is a commonly-performed procedure in ENT clinics, for patients of all ages (even small babies). It takes about 15-30 seconds. It is usually very well tolerated, and is not painful, although understandably some young children may not manage to have it done.

Airway endoscopy with general anaesthetic

In clinic, the flexible endoscopes can only be used as far as the voice box (larynx), as going down any further (into the windpipe) would be uncomfortable, producing heavy coughing. If patients have airway symptoms which suggest problems lower down, in the windpipe, bronchi or lungs, then we have to perform an endoscopy with the patient asleep, under general anaesthetic in an operating room, as a planned procedure. This allows an excellent assessment of the whole airway from top to bottom, while the patient is breathing for themselves but completely asleep and comfortable. Recovery is usually very fast, with no significant pain, and in many cases patients can go home within a few hours.

There are two main types of endoscopy under general anaesthetic:

  • Rigid endoscopy. This is usually performed by an ENT specialist, using a 4mm diameter endoscope which is about 25cm long, attached to a camera and TV monitor, which shows the procedure magnified in high definition. This is called a MicroLaryngoscopy and Bronchoscopy or MLB. This allows very high quality video and still images to be taken of all parts of the airway down to the main divisions into the right and left lungs (the bronchi). The patient is asleep on their back, breathing for themselves with anaesthetic gas and oxygen, with the head extended back slightly, and the telescope is passed through the mouth. Small endoscopic procedures can also be performed at the same time inside the airway, if needed, depending upon the particular circumstances.

  • Flexible endoscopy. This is more commonly performed by a respiratory specialist, but may also be done in addition to the rigid MLB endoscopy by an ENT specialist. This uses a longer, flexible fibreoptic endoscope, which in addition to looking at the larynx and trachea, can also reach further down the bronchi, as they divide further into the lungs. This may be more useful where the are symptoms suggestive of pathology further down the airways. This is called a flexible bronchoscopy. Again, small procedures, such as biopsies and washouts of lung mucus, can be done at the same time.

Both types of procedure are very safe and gentle, and look at slightly different parts of the airway, but there is a lot of overlap.

There are some small risks of these procedures. Passing endoscopes into the airway can cause some irritation, with coughing and reactivity of the airways afterwards. In children with severe airway problems, admission to high dependency or the intensive care unit may be occasionally needed, but this is usually identified and planned in advance for high risk cases. Because the instruments are passed through the mouth, there is also a very small risk of injuring the lips, teeth or gums, but this is uncommon.

Overall, despite requiring a general anaesthetic, these sorts of procedures are very well-tolerated, helpful and informative, allowing further treatment to be arranged if needed.