Different Tube Types
There are many different types of tubes available; all of which can be confusing. Essentially tubes can be described by:
The presence or absence of a cuff at the end,
The presence or absence of an inner cannula, or
The presence or absence of a hole or ‘fenestration.’
Tubes can also be made of different materials and be different diameters and lengths.
In a cuffed tracheostomy tube there is a cuff at the end of the tube that seals off the upper airway. If the tube is correctly positioned within the trachea, gas can only move into and out of the lungs via the tracheostomy tube.
This means that:
The airway is protected from aspiration
Positive pressure ventilation can be effectively applied via the tracheostomy tube
If the tube becomes blocked, the patient has no other way of getting oxygen to the lungs (as the upper airway is sealed off)
Fig 1 Cuffed tube
In an uncuffed tube, there is no distal cuff. Assuming a patent upper airway, air can flow through the mouth and nose, through the tracheostomy tube and past the tube in the trachea.
There is no seal in the trachea meaning the airway is not protected against aspiration and positive pressure ventilation cannot be effectively applied via the tube.
Fenestrated tubes have an opening(s) on the outer cannula, which allows air to pass through the patient's oral/nasal pharynx as well as via the tracheostomy tube. The air movement allows the patient to speak and produces a more effective cough.
Fenestrations increase the risk of aspiration. Patients who are at high risk of aspiration, or those receiving positive pressure ventilation should not have a fenestrated tube, unless a non-fenestrated inner cannula is used to block off the fenestrations.
Suctioning with a fenestrated tube should only be performed with the non-fenestrated inner cannula in situ, to ensure correct guidance of the suction catheter into the trachea.
Inner tube with fenestrations
Some tracheostomy tubes have a removable inner cannula. These allow easy cleaning of any secretions that may build up without having to change the whole tracheostomy tube. If this tube becomes blocked, simply removing the inner cannula could remove the blockage. Most wards only accept tracheostomies with inner tubes.
They are primarily designed to allow suction of secretions but can facilitate oxygen delivery. These are typically 4 mm internal diameter and have no cuff.
They are too small to provide any ventilation or removal of carbon dioxide and can only be considered an emergency method of oxygenation. Minitrachs can remain in the stoma and keep it patent in case a tracheostomy tube needs to be re-inserted.