Inner Cannulae
Inner cannulae (or inner tubes) are commonly used with tracheostomy tubes. The following table lists some of the advantages and disdvantages of using inner cannulae.
|
Advantages |
Disadvantages |
|---|---|
| Reduce the incidence of tube occlusion with sputum or blood | Add resistance to work of breathing |
| Provide a simple remedy for an obstructed tube | Some designs require a dedicated inner tube to enable connection to 15 mm breathing circuits |
| Can get lost, misplaced or contaminated |
Used correctly, inner tubes can reduce the incidence of occlusion.
However, the risks of cleaning an inner tube on a ventilated patient need to be weighed against the de-recruitment that occurs with circuit disconnection. Patients free from ventilators or on a ward should all have an inner tube in place.
Inner tubes significantly narrow the tube diameter that is available for airflow, although newer designs have thinner walls to reduce this impact.
Tubes can be fenestrated or unfenestrated. You must make sure that you know what tubes are used in your hospital, especially if the inner tube is required for connection to anaesthetic circuits.
Fig 1 is a video demonstrating changing various inner tubes and the potential connection problems that can occur.