Preformed ET tubes are moulded into special shapes that permit good surgical access in the oro nasal area. For an example (refer to picture below), a “North” facing (i.e. the tube emerges from the patient and faces towards the patients top) preformed ET tube provides very good access to the mouth for dental work .
Similarly a “South” facing preformed ET tube provides good access for the ENT surgeon needing to work in the nasal passages.
Below are some pictures of real pre formed ET Tubes
The pre formed ET Tube below has a special name. It is called a "RAE" tube, named after its inventors Ring, Adair, and Elwyn.
PEDIATRIC ET TUBES
ET tubes for paediatric patients are smaller than those meant for adults. Because the paediatric trachea is susceptible to damage by pressure, most paediatric ET tubes are uncuffed. However, cuffed versions similar to adult ET tubes exist and when used , must be inflated with care. A wide range of sizes are available.
Formulae are available to guide size selection. After intubation, depending if the fit is too tight or loose, one may have to use a different sized ET tube. For this reason, one should always keep a wide range of paediatric ET tube sizes.
The ET tubes may have a mark to guide optimum depth of placement. In these ET tubes, the vocal cords should be at the junction of the black line (see red arrow) and clear area as shown below.
Reinforced / armoured ET tubes
Reinforced or armoured ET tubes are specially designed to be resistant to kinking .
As shown below, they achieve this property by having a spiral of wire embedded into the wall of the ET tube to give it strength and flexibility at the same time.
These are particularly useful for head and neck surgery where the ET tube may be sharply bent and also compressed by the surgeons. Armoured ET tubes can be easily bent away from the area of surgery and thus improve surgical access.
LASER RESISTANT ET TUBES
Some airway surgery involves the use of laser beams to burn away tissue. These beams can ignite ordinary ET tubes and in the presence of Oxygen may cause major airway fires. Special ET tubes are available (example shown below) which resist damage by laser beams.
In the ET tube shown, there is a laser resistant metal foil wrapped around it for protection.
In this ET tube, the cuff is filled with methylene blue coloured saline.
If the laser manages to damage the cuff, the colouring will help identify rupture and the saline will help prevent an airway fire.
DOUBLE LUMEN ET TUBES
In thoracic surgery, there are times that you may need to isolate and selectively not ventilate one lung. For an example, during an oesophagectomy , one may choose to not ventilate (collapse) the right lung to provide better surgical access to the oesophagus. There are special ET tubes called “double lumen tubes” (DL tubes) to achieve this. A DL tube can be thought of as two ET tubes joined together (see graphic below). One tube is shorter and ends in the trachea and there is cuff at this level called the tracheal cuff (colored grey in the image). The other tube extends further and enters a main bronchus and has its own cuff (bronchial cuff, usually coloured blue).
