_ Trach Tube Anatomy 101
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Although several varieties of tracheostomy
tubes exist, the general anatomy remains the same. Some specialty or custom
tubes may have different/alternate features, the general “anatomy” of the tube
is essentially the same.
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Fenestration
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A fenestration
is a hole in the shaft of the tracheostomy tube, above the curvature, and
therefore also above the cuff of a cuffed trach tube. The purpose of a
fenestration is to allow for airflow upward and through the vocal cords.
Without airflow through the vocal cords, a tracheostomy patient will not be
able to produce a voice. For more information regarding voice production, see How a Voice is Produced (link).
A fenestration is not necessary to be able to talk with a tracheostomy tube, although it will likely improve the loudness and ease of producing a voice. For more information, see Speaking with a Tracheostomy Tube (link). On a fenestrated tube, there is a fenestration in the outer cannula. In order for the fenestration to be of any benefit for voicing, however, the inner cannula must also be fenestrated. There are advantages and disadvantages to fenestrated tubes. More information on this topic can be found in Fenestrated vs. Non-Fenestrated Tubes (link). Cuff
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The cuff
of a tracheostomy tube is a balloon-like structure attached to the outer
cannula below the level of the curvature. A cuff can be inflated with air to
fill the space in the trachea between the tracheal wall and the outer
cannula. When a cuff is not needed,
however, it can be deflated as well. There are various types of coughs as well
as reasons for using cuffed tracheostomy tubes. For more information on the use
of cuffed trach tubes, see Cuffed vs. Cuffless Tubes
(link).
Pilot Balloon
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This is a small plastic balloon with a
valve seal that is attached to the shaft of the balloon by a lead line. The
pilot balloon lead line is usually attached to the outer cannula near the face
plate. The cuff is inflated and deflated via this balloon and the status of the
cuff inflation can also be determined fairly well by the inflation status of
the pilot balloon. Since the cuff itself sits deep within the trachea, it is
impossible to see the cuff status directly. However, if the pilot balloon is
inflated, this is an indication the cuff is inflated as well. Similarly, if the
balloon is flat, or deflated, this is an indication the cuff is likely
deflated.
Although the pilot balloon is an indication regarding the status of the cuff, it is impossible to determine the exact degree of inflation vs deflation based on the pilot balloon alone. For more information regarding cuff status, see Proper Cuff Inflation (link). Inner Cannula
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The inner cannula sits inside the outer
cannula and is designed to be removed and cleaned or removed and replaced. As
mucous builds up within the inner cannula (normal) the airway is narrowed. By
removing the inner cannula, the airway is improved as the patient is able to
breath freely through the space of the outer cannula. This is especially
important in the event of a mucous plug that may block the entire inner
cannula. The resulting inability to breath is quickly corrected by removing the
inner cannula.
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