Tracheostomy tubes can be made of metal, rubber, silicone, Teflon, polyethylene, and PVC materials. Plastic material trachs are more common and are more frequently used. Metal trachs are used for long term use in keeping the stoma patent and in conditions where upper airway obstruction is an issue but ventilation is not an issue.
Understanding the basic parts of the tracheostomy tubes is important to be able to communicate effectively and to be able to troubleshoot problems that might arise.
3. Cuff Inflation Line:
4. Outer Cannula:
5. Inner Cannula:
8. Pilot Balloon:
Dimensions and Sizing
Tracheostomy tubes are sized by the Inner Diameter (I.D.), Outer Diameter (O.D.), and length and curvature. The I.D. is the functional size of the inner diameter and contributes to the resistance of the inspired airflow. Too small of an inner diameter may cause the patient to experience an increased work of breathing so the larger the inner diameter is better from that standpoint. On the other hand, increasing the I.D. also bears with it an increased O.D.
Too large of an O.D. may cause issues with the placement of the tracheostomy tube through the stoma. A larger size may also cause too much occlusion within the trachea which becomes an issue with weaning the patient and spontaneous breathing with a cap or speaking valve.
A tracheostomy tubes should have the I.D. size and O.D. size printed on the flange to assist care givers with identification.
Cross Referencing Trach Sizes
Tracheostomy tubes have a range of sizes that again are not standard across all trach manufacturers. This fact is not well appreciated by caregivers and can sometimes lead to confusion and difficulties in tube placement between brands. For reference, a table is provided that shows the differences between the Portex Flex DIC and Shiley SCT and Bivona Mid-Range Aire-Cuf tracheostomy tubes. This table also makes the point that sizing is not consistent across manufacturers. For example, compare a size 7.0 ID across the three manufacturers listed. The OD size between a Portex Flex D.I.C. and a Shiley SCT is the same at 9.6 however the Bivona OD is 10.0. Typically the O.D. is what one should be concerned about when exchanging one tracheostomy tube for another brand. It is important to cross reference these numbers, if possible, so that the transition goes smoothly and there are no surprises if the new tracheostomy tube happens to be a little larger and does not fit into the stoma.